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CHEMICALCHEMICAL RESEARCHRESEARCH IINN ISRAELISRAEL -.
הכנס ה - 49 של החברה הישראלית לכימיה
אוניברסטית תל - אביב , רמת - אביב
10-11 באוקטובר 1882 י כ"ג - כיין בתשרי י תשמ"ג Ii\ * ,פי."..".' __1 I """"""""""".;'.היי.ק.'''. l' ~ -_-______' ~"F
המחקר הכימי בישראל CHEMICALCHEMICAL RESEARCRESEARCHH ININ ISRAELISRAEL
הכנס ה - 49 של החברה הישראלית לכימיה
אוניברסיטת תל - אביב , רמת - אביב 10-11 באוקטובר 1982 , כ"ג -כ"ד בתשרי , תשמ"ג
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ר ע דתה כנם ======:== ==
יר"ר ישראל גרלדברג .. חברים שמחה אברהמי יעקב פנצינר
קדמה בר-אלי סטפו צירקז
שמשרו גרטטפלד אררי צישנרבסקי
ררה מנדלר אדרארר קרסרבר
עילה מררנר שמערי שצפילר
גיל נברי דפנה שרף
טל דע נרכר; תערוכה: טל( זלץ
רעדת הכנט יהחנרה הישראלית לכימיה מביעים את הערכתם לחרג לכימיה רלפקרלטה למדעים מדרייקים בארניברסיטת תל-אביב על שיתרף פערלה רהענקת עזרה בארגרו הכנס. ..
איגךי הכנט הרא בשתרף עם האגררה הישראלית להנדטה כימית ראגרד • האינגינרים לכימיה תעשייתית. ,
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תררת המארגנים נתרנה גם למרסדרת רחבררת הרשרמים מטה על תמיכתם
ותררמרתיהם לכנס זה:
בנק ריסקרנט לישראל בע"מ ררנר מיכשרר רפראי רמדעי בע"מ
בנק לארמי לישראל בע"מ אפא - טכנרלרגירת מתקדמרת בע"מ
בנק איגור לישראל בע"מ אי . אס. אי ,. מכשרר מדעי לישראל בע"מ
אלדו צירד אלקטררני כע"מ "מדע" סייאנטיפיק אינסטרימנטס בע"מ
חברת ישראמקס בע"מ קרגטררל דאטה (ישראל) בע"מ
קרמירה בע"מ אל-חמה שיררק ( 1972 ) בע"מ
לנרסיס (ישראל) ב~זמ שילרב - פירסרם, שיררק, קידרם מכיררת
אסטרגל בע"מ מ. קרכו רשרתי ( 1977 ) בע"מ
מרטכניקה בע"מ מרקררי גציגריות כימיקלים בע"מ
חמררד בע"מ לרמיטריו מכשרר מדעי בע"מ
פריד אלקטריק בע"מ לחמו צירד תהליכי בע"מ
אנקור צירד מדעי בע"מ ש.א.ק. חברה לצירד מדעי בע"מ
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אריעי הכנס מתקיימים בבניני שנקר ראירנשטייך notnpaaבפקרלטה למדעים מדרייקים;
ראה on>sפיררט bt\b\".להלך. piרק aunnמרשב nrpnanהפתיחה A>ann<החגיגי Tonנערר di'iio'Titoבארדיטררירם בר-שירה.
אררחרת קלרת. jכריכים. ni>iyערגרת niNpaoiרמשקארת ci'bpקלים oניתךr\-\}pb irrלקנרת במזנרנים השרנים בשטח oianpn.הקמפרס. d^jurnnהמזנרנים tPDioonהסמרכים למקרם הכנס נמצאים בבניך שנקר-פיסיקה (מזנרך לב). בניך גילמו. בניך משפטים רבמרזיארך בית התפרצרת. ninnxאריחרת rmieaבשרירת nie/Aiaמרגשרת IKאן pmררק במנזה המרכזית בכית הסטרדנט.
בתקרפת פגרת הלימרדים anרב המזנרנים רהמנזה פתרחים עד שעה 4 אחה"צ. מזניך גילמך פתרח גם בשערת מארחררת ירתר.
מגרשי חניה לרכב d>nniynהערמדים nioibלרשרת ^K'באי oj^nהכנס a'NSOiנמצאים in?!מיל «nyvשערי no'osnהכניםה on'מסי 4 ר - 5 לקמפרס, ליד מכרך התקנים רבניך הפקרלטה להנדסה. לצערנר • לא ניתך אישרר nunbלחנרת no©aבשטח n'^an'הפנימי bwשל oiaapnה~מפיס.
תיקים אישיים עם חרברת התקצירים, תכנית הכנס, דפי כתיבה, תגירת רחרמר אחר מחרלקים ליד שרלחך ההרשמה.. d>annu»nnהמשתתפים מתבקשים לרשרם את שמם על גבי התגירת רלעברד iniN;ארתן; n!?Nאלה nuynaaמשמשרת O>DIDכרטיס no^jaכניסה bobלכל אררעי הכנס.
המרצים רירשבי Iראשn OKהישיברתd>BTTJ nirpcpנדרשים ?!mapnלהקפדה <*ninיתרה ^על nibלרח fiהזמנים שנקבע מראש oiiaaiרמפררט lbnb .להלן. mapnהקפדה uזר naie/nחשרבה na''כדי D^B^שלכל nx'mמרצה *inw1יישמר intnהזמך המרקצב להרצאתר, רכדי לאפשר למשתתפים לתכנך שמיעת הרצארת הניתנרת בישיברת מקבילרת.
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תכנית כללית של אריעי הכנס======
יימ אי~ 10 באיקטיבר 1982
08:30 - 09:45 הרשמה (בר שירה), הכנת תציגת הפיסטרימ (שנקר).
09:45 - 11:30 מישב פתיחה חגיגי (בר שירה)
ברכית: ד"ר ר. הבר נשלא החברה הישראלית לכימיה
פריפ' י.דינשטייך רקסיר איניברסיטת תל-אביב
פריפ' א. לביא מדעך ראשל של משרד התעשיה יהמסחר
ד"ר ש. אברהמי נשיא האגידה הישראלית להנדסה כימית
מר י. שלדיב נשיא איגיד האינגינרים לכימיה תעשייתית
הרצאת מליאה מרכזית: פריפ' יהישע יירטנר (חתך פרס ישראל תשמ"ב) -
"כייינים ימגמית במחקר הבסיסי"
11:30 - 14:00 תציגת פיסטרימ בתחימי הכימיה השינימ (שנקר יאירנשטייך) ,
הרצאית מימחים על מיכשיר אנליטי מתקדם, הפסקת צהריים.
14:00 - 17:00 ישיבית הרצאית בתחימי הכימיה השינלם יבהיראת הכימיה.
16:00 - 18:00 רב-שיח על הנישא !וצרכימ יבעיית בהיראת הכימיה בישראל"
(אילם לב)
מנחה הדייך: פריפי ד. סמיאל
'. במסגרת מישב זה ייענקי פרסים לתלמידי תיכיך על עבידית
גמר מצטיינית בכימיה.
~ 17:00 - 18:00 תציגת פיסטרים (המשך).
18:00 - 19:00 קבלת פנים לא פירמלית מטעם פריפי א. גלעדי, דיקאך הפקילטה למדעים מדיייקים יפריפי א. בך-ראיבך, יי"ר החיג לכימיה (כיביד קל).
(------'-' .,~ - ___ >י__ ,.~,_, _ ..... ~_,_ ...... ~ ...... -...'oח .•_--. ~
ך ;1 ר "-'' .. ,-. f - vV --
יימ בו. 11 באיקטיבר 1982
08:30 - 09:30 מישב מליאה (אילם לב)
דברי פתיחה : פריפו ייבל נאמי - שר המדע יהפתיח
הרצאה מרכזית ד··ר אירי אייזנר - "מחקר יפתיח נחנרית כימיקלימ לישראלי· .
09:45 - 16:00 תציגה רציפה של פיסטרימ
09:45 - 12:15 ישיבית הרצאית בתחימי הכימיה השינים
12:15 - 13:30 הפסקת צהריים
13:30 - 16:00 ישיבית הרצאית נתחימי הכימיה השינימ
16:00 - 18:00 רב-שיח על הנישא ·יכיייני התפתחית של המחקר יהתעשיה הכימית בישראל נשנית ה - 80."
מנחה הדיין: פריפ' א. גלעדי נעילת הכנס,
תציגת צייד מדעי תתקיימ במשך שני ימי הכנס באילם הכניסה לבנין שנקר-פיסיקה.
מפגש תעסיקה ייערך ביים א' ה - 10.10.82 בבנין אירנשטיין.
להלן מיכא ליח זמנים מפורט של ההרצאית, רשימת העבידית המוצגיח בתציגת הפיסטרים יאיסף התקצירים שהיגשי לכנס.
תיכו הפרסימים של החברית המסחריות אשר כלילים נחיברת זי היא באחריותם הבלעדית של המפרסמים.
'-~--'''''''' ------~ - .... _-_ .. ~_.~ ___ f - vi -
.5 O^IN ,14:00 - 17:00 'K 01 .00
14.00 1 E. ZADOK and Y. MAZUR (Invited Lecture) Oxygen Atoms: Formation, Properties and Utilization in Organic Synthesis 14:45 4 S. HIRSH and D. BEN-ISHAI Amidoalkylations of Dienes with Adducts of Glyoxylic Acid. 15:05 5 S. BITTNER and Y. ASSAF Synthesis of Phospha(V)azenes by Redox Condensation Reactions. 15:25 6 S. BRAVERMAN and Y. DUAR Stereochemistry of the Electrophilic Fragmentation-Cyclization of Allenic Sulfones and Sulfinates: Stereoselective Synthesis of Chiral ObiK ,09:45 - 12:10 O1> 09:45 2 Z. RAPPOPORT (Invited Lecture) Some Mechanistic Aspects of Nucleophilic Vinylic Substitution. 10:30 10 D. HUPPERT, H. KANETY and E.M. KOSOWER Kinetics and Mechanism of Intramolecular Electron Transfer in Solution. 10:50 11 A. MINSKY and M. RABINOVITZ Singlet-Triplet Equilibrium in Doubly Charged Benzenoid Polycyclic Systems. 11:10 12 B. WEITMAN and E.A. HALEVI The Mechanism of Thermal Decomposition of Diazofluorene in Solution. 11:30 13 S. HOZ and D. AURBACH Nucleophilic "Vinylic-like" Substitution in Bicyclobutane System. 11:50 14 B.A. FEIT and U. MELAMED Configurational Stability of Vinyl Carbanions Derived from Mono-substituted Activated Ethylenes. I f - VII - .3!? D!HN ,13:30 - 15:45 'a DP 13:30 3 Z. GOLDSCHMIDT (Invited Lecture) Pentacoordinate Irontricarbonyl Complexes. Model Compounds for the Study of Organometallic Pericyclic Reactions. 14:15 15 S. AVRAMOVICI-GRISARU and S. SAREL Novel Macrocyclic Iron(II) Complexes. 14:35 16 G. SAGIV and L. NETZER Synthesis of Bifunctional Surfactants and Investigation of their Ability to Form Multilayer Molecular Systems. 14:55 17 U. ZOLER Quaternary Imidazolium Salts: Electrophilic Substitutions and their Onium-anion as an Intermediate (?) 15:15 18 I. WILNER and Y. DEGANI Photosensitized Electron Transfer Reactions in Organized Environments as Photosynthetic Models. .111 1"DW311K ,09:45 - 12:15 '3 Dl' 09:45 60 R. REISFELD (Invited Lecture) Luminescent Solar Concentrators for Energy Conversion. 10:30 62 D. MEYERSTEIN (Invited Lecture) Chemical Reactions of Unstable Compounds with Metal-Carbon Bonds in Aqueous Solutions. 11:15 63 Y. SOREK. H. COHEN and D. MEYERSTEIN Reactions of Iron(II) Protoporphyrin with Free Radicals. A Pulse Radiolytic Study. 11:35 64 M. COJOCARU andJ.M.E. GOLDSCHMIDT A Study of the Mechanism of Formation of Polymeric Species in the Mass Spectra of Pentacarbonyltrimethylsilyl-iso-cyano- Complexes of Group VI Metals. 11:55 65 H. COHEN, E.S. GOULD, D. MEYERSTEIN, M. NUTKOVICH and C.E. RADLOWSKI Intermolecular Vs. Intramolecular-Electron Transfer Reactions in Cobalt(III) Pentaamine Coordinated to Pyridinyl Radicals. 1 - VIII - i"i* ,in-p .b 'ana - 111 p»oer:niN ,13:30 - 15:55 !3 01 •,•"./. 13:30 61 (v'Z. DORI (Invited Lecture) Macrocyclic Complexes of Iron and Cobalt 14:15 66 F. FROLOW, A. EFRATY and A. EISENSTADT 2 5 2 5 A Novel [Ru4CC0) (y-CO)2(n ,n ,n -indenyl)(n -dihydroindenyl)] Cluster. 14:35 67 A. EISENSTADT and A. EFRATY Preparation of Some Unusual u-Carbene Complexes of Ruthenium. 14:55 68 U. OLSHER. E.R. BLOUT, G. SHOHAM and W.N. LIPSCOMB Complexes of Lithium Salts with the Macrocyclic Polyether Dibenzo-14-crown-4. 15:15 69 F.H. HERBSTEIN and W. SCHWOTZER Extended Donor-Acceptor Molecular Compounds Between Thiones and Chains of Bis (iodine) Molecules. A. GIVAN, I. MAYER and L. BEN-DOR Uranium in Apatites. .205 •p'uemiN ,13:30 - 15:55 '3 01* 13:30 74 J. BLUM (Invited Lecture) Catalytic Hydrogenation and Transfer Hydrogenation Reactions in Multi-phase Systems. 14:15 75 M. ROTEM and Y. SHVO Formation and Reactivity of Ruthenium Carboxylate Complexes. 14:35 76 I. PRI-BAR and J.K. STILLE Formation of New C-C and C-0 Bonds in Homogeneous Catalyzed Organotin Coupling Reaction. 14:55 77 E. KEINAN. P.A. GLEIZE and N. GREENSPOON Palladium Catalyzed Reductions with Group IVa Hydrides. 15:15 78 Y. BLUM. Y. SHVO and M. KAM Catalytic Oxidative Coupling of Alcohols with Ru,(C0)12. 15:35 79 A. EFRATI. I. FEINSTEIN-JAFFE and M. SEGAL The Application of Palladium(O)-Diisocyanide Matrices in the Heterogeneous Catalytic Hydrogenation of Alkenes and Alkynes. - IX - 103 ,13:30 - 16:00 'N 01' 13:30 81 A. LIFSHITZ (Invited Lecture) Anatomy of Complex Reaction Systems. Kinetics of Combustion Reactions from Ignition Delay Times. 14:10 82 A. PERSKY, M. BROIDA and R. RUBIN (Invited Lecture) Quasiclassical Trajectory Studies of the Dynamics of Thermoneutral Atom-Molecule Reactions. 14:50 Discussion E. POLLAK and R.E. WYATT A Semiclassical Adiabatic Theory of Resonances in 3D 15:00 86 Reactive Scattering. C. LIFSHITZ and P. BERGER Kinetic Energy Release Distributions (KERDs) for Gas Phase Ions; + 15:20 87 C4Hg0 . M.G. KATZ and T. WYDEVEN, Jr. Grafted Microporous Reverse Osmosis (RO) Membranes. 15:40 88 "n - .103 p'oenilN ,09:45 - 12:15 01' 09:45 83 S. WEISS (Invited Lecture) Picosecond Kinetics by Infrared Line Broadening 10:25 84 0. KAFRI (Invited Lecture) ] . Some Applications of a New Moire Technique in Chemistry. — 11:05 Discussion 11:15 89 M. KAGAN, A. LEVI and D. AVNIR Formation of Spatial Dissipative Structures in a Photochemical System. 11:35 90 K BAR-ELI and W. GEISELER 91 The Minimal Chemical Oscillator and Perturbations of Bistable Chemical System. 11:55 92 N. LOTAN Order and Disorder in Nonaqueous Solutions of Electrolytes. - X - .a .103 "p^DBIiTiN ,13:30 - 15:45 '3 01' 13:30 85 S. SPEISER (Invited Lecture) Novel Aspects of Electronic Energy Transfer in Solution. 14:15 93 P. PFEIFER, D. FARIN and D. AVNIR Fractal Surfaces: Chemistry in an Environment of a Non-integer Dimension Greater than Two. 14:45 94 ri. BIRNHOLTZ. Ch. AHARONI, A. NIR and N. LOTAN Non-equilibrium Chemisorption in Heterogeneous Systems. 15:05 95 A. GEDANKEN Magnetic Circular Dichroism Studies of DABCO. 15:25 96 N. LOTAN Molecular Dynamics of Polymers in Chaotropic Media. .205 "p'OemiN ,09:45 - 12:20 '3 Dl f 09:45 102"; D. CAHEN (Invited Lecture) V ____^^ Photoelectrochemical Solar Cells. 10:20 103 Ch. YARNITZKY (Invited Lecture) Double Layer Effects in Square Wave Polarography. 11:00 104 D. TALMOR and E. KIROWA-EISNER Delayed Open-Circuit Voltammetry. 11:20 105 J.Y. BECKER, D. DOLPHIN, J.B. PAINE III and S.F.B. PICKETT Electro-catalytic Reduction of O~ by Metallo-porphyrin Monomers and Dimers. 11:40 106 H. YAMIN and E. PELED Low-rate Li/S Organic Cell. 12:00 107 JLJJABAI and J. BINETH The Behaviour of the Li/SOCl2 System at Elevated Temperatures. - XI - .0 o!?lN ,14:00 - 15:55 'K Dl nyc? 14:00 115 E.V. DEHMLOW (Invited Lecture) Phase Transfer Catalysis; Fundamentals and Recent Developments. 14:45 118 Ch. SHEINDORF, M. REBHUN and M. SHEINTUCH Adsorption from a Multicomponent Solution. 15:05 119 M. BERC2ELLER and H. ARTZI Preparation of a Dual Function Reforming Catalyst for the Production of a-Naphtbol from Tetralon Based on Bond's Theory. 15:25 120 M. WEISS-YONOVITCH and Y. SASSON Converting of Alkyl Chlorides to Alkyl Bromides by PTC. Influence of PTC on Equilibrium Position of Reversible Reactions. 15:40 121 L. MENDELOVICI and Y. SASSON Gas Phase Halogen Exchange in Alkyl Halides Catalyzed by Supported Molten Phosphonium Salts. .a in - .5 OtnK ,09:45 - 12:10 '3 Dl> 09:45 116 A. CANTONI (Invited Lecture) Problems of Scaling up to Jumbo Agitated Reactors, and Ergonomic Interrelation Between their Operators and their On-line Computer. 10:30 122 I. KOENIGSBERG and J. JAGUR-GRODZINSKI Flame Retarding Properties of the Block Copolymers of Bromostyrene and Styrene 10:50 123 L.M. SHORR. J. SEGALL and Z. BLUTSTEIN The Chemical Hygiene of Process Solvents. Systems Containing Tertiary Amines. 11:10 124 M. REBHUN. H. GRYNBERG, Ch. SHEINDORF and R. OFER Treatment of Industrial Waste from Oil Refineries 11:30 125 M. SHORR and E. WEINTRAUB Influence of Chloride in Phosphoric Acid on the Corrosion and Electro chemical Behaviour of Irou and Nickel Alloys. 11:50 Discussion. 1 - XII - .0 •in - 'A 3'win ,rpn .5 ,13 :30 - 16 :00 '3 Dl' Y. ZIMMELS (Invited Lecture) Applications of Magnetic Liquids. 14:20 126 K.S. SPIEGLER, T.S. BRUN and A. BERG Water and Salt Transport Through an Ion-exchange Membrane. 14:40 127 R. NEUMAN and Y. SASSON Simultaneous Reaction and Distillation in a Packed Column. 15:00 128 E. WELLNER, N. GARTI and S. SARIG Crystal Structure Modification of Saturated Fats by Food Emulsifiers. 15:20 129 Z. KRAUS. M. FRENKEL and N. GARTI Emulsifiers as Weighting Agents. 15:40 130 H. ISAACS. N. GARTI and M. FRENKEL Dispersing Agents in Aqueous and Organic Systems. .111 V>oenTiN ,14:30 - 17:30 14:30 136 S. BERMAN (Invited Lecture) The Analysis of Seawater for Trace Metals - A Challenge to Analytical Chemists. 15:10 137 M. ARIEL (Invited Lecture) Anodic Stripping Analysis Applied to Environmental Surveillance. 15:50 Discussion (Coffee) 16:10 139 A. LORBER and Z. GOLDBART Elimination of Drift from Analytical Signals in Multielement Analysis by the Generalized Internal Standard Method. 16:30 140 R. BAR and Y. SASSON Determination of Carbonate/Bicarbonate Ratio by C NMR. 16:50 141 E. SHOENBERGER and J. KASSOWITZ Micro Dry Ashing for Trace Selenium Determination in Organic Matrices, 17:10 142 I.B. BRENNER. I. GAL, H. ELDAD, L. HALICZ and D. HOFFER Application of the Inductively Coupled Plasma for the Quantitative Analysis of Geological and Related Materials, 1 - XIII - .111 I^DBJIIK ,11:30 - 13:30 «K Ql"> "Developments in Analytical Methods and Instrumentation" nye> vspn 11:30 144 D. ORD and J. FREMAJER Distributed Local Area Networks for Chromatography Laboratories. 12:00 145 P. VAN HOUT Recent Development in High Resolution Chromatography: Ultra Performance Fused Silica Capillary Columns and Liquid On-column Sampling. 12:20 146 D. FUSTER Diode Array Technology Applications in UV/VIS Spectrophotometry and LC/UV Detection. nr nunn imom rnaon imne/flN niNnn by romn "n - .104 IN 222 np»tj*>3-1pJ» ,13:30 - 16:00 lH DT> 13:30 147 J. DUDLEY HERRON (Invited Lecture) "Turning Water into Wine": Student Difficulties in Solving Problems, 14:20 148 TIKQ .K 14:40 149 naiynn !?ta pnan 15:00 150 taia .n 15:20 151 bam .KI >3v-p ."! .nix . ? "yau"n pbn x»n n'n>Dn o 15:40 152 bw - XIV - .a 'ails :i"i> . V»OW31IKI ipjw »3'33 HN leipnn iimona JOIVJ ;uixnn .on .on may vspii yjo >iain 1 19 M. SAHAI. H.E. GOTTLIEB, A.B. RAY, A. ALI, E. GLOTTER and I. KIRSON Steroidal Lactones Related to the Withanolides from Physalis Peruviana L. 2 20 D. BARKAN. S. CARMELY, A. GROWEISS, D. CZARKIE, Y. KASHMAN and U. SHMUELI Marine Diterpenes with a Cembrane Skeleton: Structure and Chemistry. 3 21 Y. KASHMAN and A. GROWEISS Latrunculin, a Marine Macrolide from the Sponge Latrunculia Magnifica. 4 22 R. SEGAL, I. FEUERSTEIN and A. DANIN Identification of Several Chemotypes of Artemisia herba alba Asso from the Middle East. 5 23 I. TAMIR, A. ABRAMOVICI, R. SEGAL and I. MILO-GOLDZWEIG The Red Blood Cell as a Model for Studying the Mechanism of Citral Teratogenicity. 6 24 E. BREUER. J. DEUTSCH and P. LAZAROVICI A Convenient Synthesis of the Aggregation Pheromone of Tribolium Castaneum and T. Confusuro. 7 25 V. VANDE VELDE, D. LAVIE. R. ZELNIK, A.K. MATIDA and S. PANIZZA Cordialin A and B, Two New Triterpenes from Cordia verbenaceae DC (Boraginaceae). 8 26 Y. SEGALL and J.E. CASIDA Some Properties of the Phosphorothiolate 5^-oxide Intermediate. 9 27 I.I. ZIDERMAN and J. BELAYCHE Alkali-catalysed Depolymerisation of Cellulose in the Presence of Anthraquinone. 10 28 E. MENACHEMOFF, 0. AWERBUCH and R. HABER Novel Derivatives of 6-Ethoxy-l,2-Dihydro-2,2,4-Trimethylquinoline (Ethoxyquin) and Their Biological Activities. 11 29 A. GAATHON. B. FRIDLENDER and N. ISRAELI The Fluorescence of Thyroxi-Fluorescein Conjugate and its Application in a Diagnostic Immunoassay for Thyroxine. 12 30 J. VAN MIL. L. ADDADI, M. LAHAV and S. SIFNIADES A Model for the Generation and Amplification of Optical Activity. 13 31 I. WEISSBUCH. E. GATI, L. ADDADI, Z. BERKOVITCH-YELLIN, M. LAHAV and L. LEISEROWITZ Induced Resolution of o-Amino Acids by Crystals of a-Glycine Growing at the Interface. - XV - 14 32 A. BALAN. Y. SEGALL and A. TISHBEE Racemic and Pseudoasyraraetric (±) Dialkyl Methylphosphonates Isolation and NMR Studies. 15 33 Y.H. KIM, A. BALAN. A. TISHBEE and E. GIL-AV Chiral Differentiation by P-(+)-Hexahelicene-7,7'-Dicarboxylic Acid Disodium Salt. Resolution of DNP-a-Amino Acid Esters by High Performance Liquid Chromatography. 16 34 S. WEINSTEIN HPLC Resolution of Enantiomers Using Chiral Additives in the Mobile Phase. Extension of the Method to Compounds other than the Protein Amino Acids. 17 35 P.A. RAMAIAH and E. GIL-AV Isolation and Assignment of Configuration of the Diastereomeric trans-Chloro(N,N-Dimethyl-D-phenylglycine)(3-ethylcyclopentene) Pt(II) Complexes. 18 36 A. RAMAIAH, E. GIL-AV and A. GEDANKEN Correlation between Circular Dichroism and the Absolute Configuration in the 3-Alkylcyclopentene System. 19 37 Z. GOLDSCHMIDT, B. CRAMMER and R. IKAN Thermal Acid-Catalysed Rearrangements of Trans Methyl Chrysanthemate. 20 38 S. SAREL, N. WONGVISETSIRIKUL and S. COHEN The Formation and Crystal Structure of a [2+5] Cycloadduct. 21 39 J. DEUTSCH and M. CHRIKI Stereochemical Effects on Mass Spectral Hydrogen Rearrangements in Bicyclic Diones under Electron Impact. 22 40 E.M. KOSOWER, N.S. KOSOWER and A. RADKOWSKY Fluorescent Thiol Labeling and Other Reactions with Bromobimanes; Glutatitione Sulfide (GSG). 23 41 A.L. WEIS Tautomerism in Dihydro-1,3,5-Triazine Systems. 24 J. ZIZUASHVILI and B. FUCHS 42 Photochemical Behaviour of Biased Homo-conjugated Ketones: 2-Methylspiro[5.5]undeca-l,3-dien-7-one. 25 Z. GRAUER. D. AVNIR, S. YARIV and L. HELLER-KALLAI 43 Surface Effects on Conformation and Spectra of Dibenzotropone Adsorbed on Various Montmorillonites. 26 S. BRAVERMAN and J.C. MARTIN 44 Ortho Lithiations of Arenesulfinic Acids. New Method for Electrophilic Aromatic Substitution. 1 - XVI - 27 45 S. BRAVERMAN, D. REISMAN, M. FREUND, D. RABINOVICH and F. FROLOW Skeletal Rearrangement of a 2,6-Dithiaadamantane-2,2,6,6-Tetraoxide Derivative during Thermal and Photochemical Sulfur Dioxide Extrusion. 28 46 A.L. WEIS and Z. PORAT Dynamic NMR Investigation of the Tautomerism in Dihydropyrimidines 29 47 Z. GOREN, P. DAN and I. WILLNER Complexation of Organic Compounds to Cyclodextrins - Artificial Models for Substrate-Receptor Interactions in Enzymes. 30 48 Y. DEGANI and I. WILLNER Control of Photoinduced Electron Transfer Reactions in Positively Charged CTAB Micelles, DODB Vesicles and ZrO2 Colloids. 31 49 J.Y. BECKER and B. ZINGER Anodic Oxidation of Allenic Hydrocarbons in CH^CN. 32 50 M. HALPERN. Y. SASSON and M. RABINOVITZ Evidence of Hydroxide Ion Extraction in the Phase Transfer Catalyzed Isomerization of Allybenzene. 33 51 S. SHATZMILLER, E. BAHAR and R. LIDOR Geometrically Controlled Dimerization of Acetone-0-methyl Oxime, Uses for Pyrrole Synthesis. 34 52 A. KALIR, J.M. KAMENKA and P. GENESTE Preparation of Substituted Piperidinocyclohexanecarbonitriles. A New Variant of the Strecker Reaction. 35 53 S. BRAVERMAN, D. REISMAN and M. FREUND Novel Synthesis of Vinylallenes and 1,3-Dimethylenecyclobutanes Through Base-Catalyzed Dimerization and Cyclodimerization of Allenic Sulfones. 36 54 S. BRAVERMAN and M. FREUND The Synthesis of New 3,4-Dimethylenethiolane Derivatives: Potential Tetramethyleneethane Precursors. 37 55 A.L. WEIS and M. BERNSTEIN The Reaction of Benzylidenacetylacetone with Benzamidine. 38 56 A.L. WEIS, F. FROLOW, M. BERNSTEIN and J. FAHIMA Synthesis and Crystal Structure of 2,4-Diaza-6,7-Benzo-8- 0xabicyclo[3.3.1]-Nonanes. 39 57 S. ANTEBI and Z. GOLDSCHMIDT The Reaction of Carbenes with Cycloheptatriene-Fe(CO)_ Complex. 40 58 E. KEINAN and Z. ROTH A New Indicator Substrate for Classification of Nucleophiles. 41 59 E. KEINAN, M. SAHAI and I. KIRSON Reductive Elimination of Vicinal Oxygen Function with Palladium(o). Applications in Withanolides Interconversions. - XVII - 42 80 E. KEJCNAN and M. PERETZ Palladium Catalysed Allylic Alkylation with Allenyl Stannane 43 143 N. GARTI, E. WELLNER. A. ASERIN and S. SARIG Analysis of Sorbitan Fatty Acids Esters by HPLC. 44 131 J. SEGALL. L.M. SHORR and S. WEINER Synthesis of Dialkylphosphoric Acids from POC1,, P9O5 an(* Alcohols. 45 132 Y. SASSON, N. GARTI and A. ASERIN Preparation of Monoglycerides of Fatty Acids from Epichlorohydrin by Phase Transfer Catalysis - Part I. 46 133 R. SHWARTZ. M. FRENKEL and N. GARTI Multiple Emulsions: A Novel Technique to Overcome the Unpleasant Taste of Drugs. 47 134 E. PROSS and Y. SASSON Extraction of Alkoxide Ions by Liquid Anion Exchangers. 48 135 M. BERCZELLER Determination of the Crystallinity of Aluminium Oxy-hydroxide Using Thermal Analysis. 49 71 N. YELLIN Low Temperature Synthesis of Chalcogenides. 50 72 E. FUCHS, H. COHEN, K. WIEGHARDT and D. MEYERSTEIN On the Difference in the Oxydation of 1,4,7 Triacetate-1,4,7 Trazacyclonane Nickel(II), in Aqueous Solutions, by Hydroxyl Radicals and Electrochemically. 51 73 H. COHEN, G. GINZBURG, N. JUBRAN and D. MEYERSTEIN Effect of Methylation on the Properties of 1,4,8,11 Tetraazacyclo- tetradecane Nickel(I) in Aqueous Solutions. 52 108 H. RELLER, E. KIROWA-EISNER and E. GILEADI Ensemble of Microelectrodes: Digital Simulation by the Two-Dimensional Expanding Grid Method Applied to Cyclic Voltammetry. 53 109 Z. HARZION, N. CROITORU, D. HUPPERT and S. GOTTESFELD Time Resolved Photocurrent Photopotential and Photoluminescence Study of n Type CdS and CdSe Photoelectrodes. 54 110 J. RISHPON, I. RESHEF and S. GOTTESFELD Ellipsometric and Impedance Measurements of Oxide Film Grown on Ruthenium Electrodes. 55 111 D. ISSAHARY and D. KI3YERSTEIN Cooperative Phenomena in the Electrochemical Behaviour of Anodes Modified by Anodic Deposition of Nickel Complexes. 56 112 G. GINZBURG (the late), B. ZINGER and J.Y. BECKER A Semi-Empirical Method for Resolving Overlapping Waves in Cyclic Voltammetry. 57 113 M. ELAM, E. PELED and E. GILEADI Cyclic Voltammetry of Pb and Sn in Solutions of Aluminum Bromide and KBr in Aromatic Hydrocarbons. - XVIII - 58 114 R. TULMAN. A. GOLAN, A. MEITAV and E. PELED Calcium - Thionyl Chloride High-Rate Cell. 59 97 Z. KOTLER and A. NITZAN Local Field Enhancement in Aggregated Dielectric Films. 60 98 C. LIFSHITZ, M. GOLDENBERG and Y. MALINOVICH Time Resolved Photoionization Mass Spectrometry. 61 99 N. MANOR. R. REISFELD and D. AVNIR Fluorescence Studies of Ruthenium Tris-Bipyridine and of Europium Tris-Benzoylacetonate Adsorbed on Porous Supports. 62 100 E. NISSANI, B. HAYMAN and R. KOREN The Kinetics of Binding of Bilirubin to Bovine Serum Albumin. 63 101 D. ROJANSKY and D. HUPPERT Picosecond Time Resolved Electronic Energy Transfer in Mixed Crystals and Fluid Solutions. 64 101a D.A. WEITZ, S. GAROFF, J.I. GERSTEIN and A. NITZAN Resonance Raman Scattering and Fluorescence of Molecules Adsorbed on Silver-Is?and Films. o^Tinya o'Nain ojab lettirw nmayn ba bv by liny baa nji'byn n»3n'n 1DD13 riA^n - P .fiNjnna ne/Aio rniay - 0 ,mnnn riKsin - L manrn n»n>a ORGANIC CHEMISTRY - 1 - OXYGEN ATOMS: FORMATION, PROPERTIES AND UTILISATION IN ORGANIC SYNTHESIS Elazar Zadok and Yehuda Mazur Department of Organic Chemistry The Weizmann Institute of Science, Rehovot 76100, Israel We have found that oxygen atoms formed by microwave discharge of 02 and CO2 can be used for oxidation of organic compounds in preparative scale. The lecture will deal with the reactions of O-.atoms produced in this way with saturated and unsaturated organic compounds. The main products of the oxidation of the saturated compounds were tertiary alcohols formed with high retention of configuration, while the oxidation products of olefins were epoxides and carbonyl compounds. Aromatic compounds led mainly to hydroxylation at ortho and ipso positions. A mechanism is postulated for this reactions,involving the intermediacy of triplet diradicals, in the case of unsaturated compounds, and triplet radical pairs in the case of saturated compounds. - 2 - SOME MECHANISTIC ASPECTS OF NUCLEOPHILIC VINYLIC SUBSTITUTION Zvi Rappoport Department of Organic Chemistry The Hebrew University, Jerusalem 91904, Israel Many mechanistic routes are available for the substitution of a nucleofuge X at- tached to a vinylic carbon by a nucleophile Nu (eq. 1) « These involve addition-elimi- R3R2C =C tX)RJ + Nu~-* R3R2C=C(Ru)R1 (1) p a nation and elimination-addition routes, and reactions via carbocations, carbanions and 1 2 radicals. The two most important routes, i.e., nucleophilic addition-elimination ' 3 and vinylic SM1 differ in many mechanistic respects. The nucleophilic addition-eli- mination is activated by electron-withdrawing a-substituents, the nucleofugality of X follows the order F>>Cl^Br and the stereochemistry is mostly retention of configu- ration for good nucleofuges and stereoconversion for poor nucleofuges. The SN1 route is facilitated by electron-donating a-substituents, the nucleofugality order is Br>Cl and the stereochemistry is stereoconversion or partial inversion. These routes will be discussed in relation to two mechanistic questions: (a) Whether the addition-elimina- tion process is multi-step proceeding via an intermediate carbanion or is a single step route and (b) The role of ion pairs in the SI route. 1. Z. Rappoport, Adv. Phys. Org. Chem., 7_, 1 (1969). 2. Z. Rappoport, Ace. Chem. Res., 14, 7 (.1981). 3. P.J. Stang, Z. Rappoport, M. Hanack and L.R. Subramanian, "Vinyl Cations", Aca- demic Press, 1979. 1 - 3 - PENTACCORDINATE IRDNTRICARBONYL COMPLEXES. MODEL COMPOUNDS FOR THE STUDY OF ORGANOMETALLIC PEPICYCLIC REACTIONS Zeev Goldschmidt Department of Chemistry, Bar-Ilan University, Ramat-Gan Despite current interest in symmetry-controlled organic reactions study of peri cyclic reactions of transition metal organometallic compounds has so far been rather limited. The recent extensive application by Hoffman of molecular orbital theory to determine the electronic structure and bonding in organometallic complexes provided a convenient framework for our search of pericyclic reactions of these compounds. A qualitative analysis of symmetry-allowed reactions of square pyramid (_1) and trigonal bipyramid (2) pentaccordinate irontricarbonyl complexes will be pre- sented. It will include the presentation of correlation diagrams and frontier orbital interactions for cycioaddition of cyclic heptatriene complexes, diene-diene isomerizations and [1,3] sigmatropic shifts of c,n-allyl complexes. Symmetry- allowed metal-hydrogen, metal-carbon and metal-metal dyotropic shifts involving square pyramids to trigonal bipyramid interconversions will also be discussed. V - 4 - Amidoalkylations of Dienes with Adducts of Glyoxylic Acid. S. Hirsh and D. Ben-Ishai Department of Chemistry, Technion-Israel Institute of Technology, Haifa. Amidoalkylation of butadiene with glyoxylic acid-methyl-carbamate adduct 1_> at room temp, and in the presence of an acid catalyst, afforded the neutral vinylbutyrolactone derivative 2_ {12%~) and the acid pipecolic acid derivative 3 (9%). H R2NH NHCO2Me HO CO2Me HO-CH-CCI "2 H NHCO2Me 1 HX V CO2Me NHCO2Me NHCO2Me i 5_ X=Br,SMe 16 Isoprene, 1,3-cyclohexadiene, 2,5-dimethyl-2,4-hexadiene, 2,4-dimethyl-l,3- pentadiene and other dienes were found to react similarly and gave lactones as the major reaction products. Reacting the vinyllactone 2_ with amines as nucleophiles afforded the amides 4. Soft nucleophiles like HBr and MeSH reacted with the vinyllactone 2^ in an SN2 type reaction and afforded the unsaturated derivatives 5^. The bromo acid (5, X=Br) was further converted to the methoxy ester 6^ on refluxing with methanol. The mechanism of the formation of the lactones from the adduct 1 and dienes will be discussed. - 5 - 0 SYNTHESIS OF PHOSPHA(V)AZENES BY REDOX CONDENSATION REACTIONS Shmuel Bittner and Yonit Assaf Department of Chemistry, Ben-Gurion University of the Negev Beer Sheva, 84120, ISRAEL Triphenylphosphine reacts with primary amides in the presence of diethyl azodicar- boxylate to produce N-substituted phospha(V)azenes along with diethyl hydrazinedi- carboxylate. Aryl carboxamides, haloacetamides, and acrylamide produce the corres- 0 II ponding phospha(V)azenes (R-C-N=PPh_), aromatic and aliphatic primary sulfonamides gives rise to N-sulfonylphospha(V)azenes (R-SO_-N=PPh,), and diphenylphosphinamide 0 ^ •* 0 II II (Ph-P-NH-) gives the phospha(V)azene containing two phosphorus atoms (Ph2P-N=PPh2). The reaction of bis-amides with triphenylphosphine produces bis-phospha(V)azenes as does the reaction of bis-phosphines with mono-amides. Heterocyclic systems, con- taining two phospha(V)azene linkages, have been prepared from bis -amides and bis- phosphines in the presence of diethyl azodicarboxylate. A novel variation of the reaction of a phosphine, an amide and an azo ester is the reaction of azodicarbon- amide with phosphines. This reaction, using a variety of phosphines, has been shown to produce a new class of phospha(V)azenes with a semicarbazidoacyl group on the nitrogen atom (R3P=N-C0-NH-NH-C0-NH2). Structure proof for these compounds and mechanisms for these reactions will be discussed. - 6 - STEREOCHEMISTRY OF THE ELECTROPHILIC FRAGMENTATION-CYCLIZATION OF ALLENIC SULFONES AND SULFINATES: STEREOSELECTIVE SYNTHESIS OF CHIRAL a,g-UNSATURATED y-SULTINES. Samuel Braverman and Yizhak Duar Department of Chemistry, Bar-Ilan University, Ramat-Gan Following our initial reports on the spontaneous fragmentation-cyclization of allenic sulfones and sulfinates to ysultines, the stereochemistry of the reaction was examined. Addition of Br9 or CH,SC1 to (+) and (-)-a-methylpropargyl Y-methylallenesulfinates, as well as to (-J-y-methylallenyl and (-J-y-Jt-butyl- allenyl t-tutyl sulfones, generated optically active 6-bromo-(or 8-methylthio)- y-alky1-a,$-dehydro-y-sultines. 0 CH, I; il II CH, K R R = CH,, t-Bu R = CH, t-Bu X = Br, CH3S The chirality of the allene was transferred to the allylic carbon of the sultine as can be seen by oxidation of the sultines to sultones. The relative structure of each diastereomeric sultine was determined by its NMR data. The weight of evidence argues against the intermediacy of a vinyl sulfene and suggests the intervention of an ionic mechanism wherein the sulfonyl oxygen attacks the bridged carbonium ion. Assuming an ionic reaction mechanism and determination of the absolute configuration of the allenyl sulfones, allows one to further deter- mine the absolute configuration of each sultinic diastereomer. 1. S. Braverman and D. Reisman, J. Amer, Chem. Soc. , 99_, 605 (1977); Tetrahedron Letters 1753 (1977). 1 - 7 - 0 STEREOCHEMICAL AND ELECTRONIC FACTORS IN HYDROCARBON CARCINOGENESIS Yitzhak Ittah Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot. D.R. Thakker, H. Yagi, M. Croisy-Delcey and D.M, Jerina Laboratory of Bioorganic Chemistry, National Institutes of Health, Bethesda, Md. 20205 Two diastereomeric diol epoxides can be obtained on a benzo-ring of Polycyclic Aromatic Hydrocarbons from vicinal trans-dihydrodiols (1). The oxirane oxygen and the benzylic hydroxyl group can have either ds (diol epoxide-1, DE-1,2) or trans (diol epoxide-2, DE-2,3) relative stereochemistry. DE's with quasi-diequatorial hy- droxyls exhibit higher tumoregenicity than those with quasi-diaxial conformation C1D. The steric hindrance at the bay-region of B[c]Ph causes its DE-1 and DE-2 (newly synthesized) to prefer the quasi-diequatorial conformation. This was unequivocally assigned by the large values of Ju u = 8-9 Hz. Both DE-1 and DE-2 have similar H3-Hu high tumoregenic activity C2D. HO* l.NBA l^^ 2. Amberlite OH Fluorination of BCcHPh at any of the positions 1,2,3, or 4 hardly affects the carcinogenicity relative to the parent hydrocarbon. However, the K-region 6-fluoro- derivative was 5-fold more active than BCcDPh [3D. 1. H. Yagi, D.R. Thakker, R.E. Lehr and D.M. Jerina, J. Org. Chem., 44, 3439 (1979). 2. W. Levin, A.M. Mood, R.L. Chang, Y. Ittah, M. Croisy-Delcey, H. Yagi, D.M. Jerina and A.H. Conney, Cancer Res., 40, 3910 (1980). 3. Y. Ittah and D.M. Jerina, J. Fluorine Chem., 16, 137 (1980). j - 8 - Single Group Rotation. An Early Step in the Transduction of Chemical Stimuli: Neurotransmitters. A Structural and Mechanistic Model for Ionic Channels in Biomembranes Edward M.Kosower Department of Chemistry, Tel-Aviv University, Ramat-Aviv, Tel-Aviv, Israel and Department of Chemistry, State University of New York, Stony Brook, New York, USA 11794 The rotation of a single group ["SGR"] is postulated as an early step in the transduction of certain molecular signals. Specific illustrations are given for several neurotransmitters. Simple formula drawings show the local motion within the stimulus molecule-receptor combination. Molecular models for ion "gating" with acetylcholine, glutamate and q-aminobutyrate are presented. The model for the acetylcholine receptor (AChR) is compatible with d-tubocurarine inhibition of AChR, electron micrographic evidence for a 20A central "hole" in the AChR and desensitization of AChR by two molecules of acetylcholine. Models for the ion channel of the acetylcholine receptor (AChR) and the sodium channel in biomembranes are proposed, utilizing a-helical polypeptides with "channel-active" (CAl amino acids in the sequence: glu(l), lys(5), g1u(8), lys (12) ...accompanied by a counterpart set: lys, glu, lys> glu... The channels conduct ions via similar mechanisms, in which the key steps depend upon single group rotation (SGR) of CA side chains. The difference between thiol-reactive agonists and antagonists for disulfide-reduced AChR may be explained using the model. Diversion of the opening/closing mechanism of the Na4* channel can account for the action of channel-opening toxins (two classes: (A) grayanotoxin I, batrachotoxin, aconitine, veratridine (B) scorpion and sea anemone toxins). Channel closing toxins act by blocking (tetrodotoxin, saxitoxiix, with brevetoxin P proposed as channel-filling. Gating (charge motion within the membrane) and threshold voltage opening are natural properties of the model: the ionic selectivity of the channel may have a steric and kinetic basis. The similarity in molecular weight for AChR and the Na+ channel is utilized to suggest a composition for the latter. The possibility that other ion channels (K , Ca , Cl~) function in the same way is noted. 1 - 9 - 0 COMPOSITE SORBENTS - APPLICATIONS IN BIOMEDICAL ENGINEERING A. Tabak, N. Lotan, S. Sideman and U. Taitelman Departments of Chemical and Biomedical Engineering, and the School of Medicine, Technion, Haifa, Israel. Hemoperfusion is a clinical operation by which undesired materials are removed .rom the blood of intoxicated persons, using an extracorporeal device. The key element of such a device is the toxin-removing unit, usually a column packed with adsorbed particles. The demands set for such a unit are: high speci- ficity, high capacity and appropriate blood flow-through characteristics. The present report describes the development of hemoperfusion columns made up of composite sorbent particles for the removal of Paraquat ( an herbicide), using Fullers' Earth. The highly specific adsorbent considered is a finely divided powder mater- ial, of large surface area. This powder is not biocompatible. Furthermore, the flow characteristics through a powder bed are not appropriate. Hence, we have incorporated the powdered adsorbent into a gel-type material (agarose), and obtained composite sorbent beads exhibiting desired properties. A detailed investigation on the equilibrium and the dynamic performances of the Fuller's Earth -containing beads was carried out. Langmuir-type equili- brium isotherms were obtained. The maximal adsorption capacity of the beads was found to be 51.2 mg Paraquat/gr Fullers' Earth, which is identical to the value obtained with the uncoated material. The mass transfer characteristics of the composite agarose beads were established, by measuring the adsorption and the escape rates of 14C-labelled Paraquat. The values obtained for the diffusion of Paraquat (D= 1.4-2.8x10 cm /sec) have been related to the composite characteristics of the sorbent, as well as to the structure of the rolysaccharide and of the water contained. The application of another hemoperfusion column made of composite beads, containing Zirconia for the removal of excess inorganic phosphate ions from the blood, will also be discussed. - 10 - Kinetics and Mechanism of Intramolecular Electron Transfer in Solution Dan Huppert, Hannah Kanety and Edward M. Kosower , Department of Chemistry, Tel-Aviv University, Ramat-Aviv Tel-Aviv, Israel 69978 ( also Department of Chemistry, State University of New York, Stony Brook, New York ]1794 USA) The picosecond pulse generated S, nD state of 6-N-4-methyl- phenylamino-2-naphthalenesulfonic acid'NrN-dimethylamide (TNSDMA) decays by intramolecular electron transfer (IET) somewhat faster than the appearance of the product, an equilibrium mixture of the solvent cluster motion (1/t-i, lowest dielectric relaxation rate) over a wide range of temperatures with log k linear in 2/31og l/n. Up to ca -15°C, "slow" IET processes probably vary in the same way, but at higher temperatures are controlled by local group motion (l/t2/ second lowest dielectric relaxation rate) . A molecular model for the S^ t state-methanol complex is presented. 1 - 11 - 0 SINGLET-TRIPLET EQUILIBRIUM IN DOUBLY CHARGED BENZENOID POLYCYCLIC SYSTEMS Abraham Minsky and Mordecai Rabinovitz Department of Organic Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel. Fused benzenoid systems such as anthracene, phenanthrene, chrysene and 3,4-benzophenanthrene were reduced with lithium, sodium and potassium in various solvents to the corresponding antiaromatic doubly charged species. The NMR and ESR patterns of the dianionsrevealed a strong dependence on the counter- cation, solvent and temperature. This dependence is interpreted by the existence of an equilibrium process between the singlet ground state and a thermally accessible excited triplet state of the antiaromatic dianions. The direction and extent of the equilibrium is determined by the energy gaps between the LUMO and HOMO of these charged species which depends, in turn, on the topology of the hydrocarbon and on the solvation properties of the obtained salt. When the equilibrium tends toward the triplet state, NMR line broadening process is 2 observed - up to a total disappearance of the signals and, in frozen, rigid solutions, a Am =2 ESR signal is revealed. 1. Bates, R.B. in "Comprehensive Carbanion Chemistry", Elsevier: N.Y. 1980, Part; A, pp. 1-54. 2. Gunther, M. "NMR Spectroscopy", John Wiley, N.Y. 1980; pp. 325-331. 3. Wertz, J.E. and Bolton, J.R. "ESR Elementary Theory and Practical Applications", McGraw-Hill: N.Y. 1972; pp. 232-246. - 12 - 0 THE MECHANISM OF THERMAL DECOMPOSITION OF DIAZOFLUORENE IN SOLUTION. by Berta Weitman and E. Amitaf Halevf Department of Chemistry, Technion-Israel Institute of Technology, Haifa. The thermal decomposition of diazofluorene (DF) in benzene at 70°C is found to differ from that of diphenyldiazomethane »^ in two important aspects: (a) The reaction is cleanly first order when oxygen is completely excluded. Even traces of 0£ retard the reaction,which departs from first order kinetics. These are restablished, with a greatly reduced rate, at high concentrations of dissolved O2. (b) Neither fluorenone nor fluorenoneazine is produced in any of the above conditions,bifluorenylidine (BF) being the only product observed. The Arrhenius parameters for the uninhibited reaction (Eg=2'».7±0.6 kcal/mole; log10A=12.0±0.A) and the limiting behavior of the 02"inh?bited rates at high and low O2 concentrations are consistent with the following mechanism, which is also supported by semi-empirical (MNDO) computations: k 3F + DF Its principal features are: (i) reversible tntersystem crossing between singlet and triplet DF; (ii) quenching of the latter by a still uncharacterized oxygen- ated product (FO2); (iii) independent formation of triplet fluorenylidene (3F) from both DF and 3QF; and (iiii) the absence of any role for the singlet carbene (IF). The implications of our findings for the interpretation of recent studies of the photochemical decomposition of DF are discussed. References 1. D. Bethell, D. Whittaker and J.D. Callister, J_. Chem. Soc, 2466 (1965). 2. (a) T. Oncescu, M. Continanu and G. Balaceanu, Rev. Roumaine Chim. 17, 213 (1972); (b) M. Continanu, T. Oncescu and R.N. Schindler, ibidTUT, 559 (1973). 3. J.T. Zupancic and G.B. Schuster, J_. Amer. Chem. Soc. (a) 102, 5958 (I98O); (b) 103, 9*6 (1981). - 13 - NUCLEOPHILIC "VINYLIC-LIKE" SUBSTITUTION IN BICYCLOBUTANE SYSTEM. S. Hoz and D. Aurbach, Dept. of Chemistry, Bar-Ilan University, Ramat-Gan, Israel. The mechanisms and the kinetics of the reactions of various nucleophiles with 3-halobicyclobutanecarbonitrile (1) were investigated. The reactions of alkoxides with 1^ produces the 3,3-dialkoxycyclobutanecarbonitrile ketals (2). The mechanism of their formation involves haloethers which are formed in the first stage. These then produce the appropriate oxocarbonium ions in the next step. The oxccarbonium ions are capable of trapping t-BuOH (which is otherwise unre- active). In a solution of CF-CH^O" in t-BuOH, among the other products of this reaction are mixed ketals whose stereochemical composition is kinetically con- trolled. This composition differs markedly from that found in the thermodynami- cally equilibrated system. Substitution of Br for Cl in 1^ alters the ratio between the mixed ketals and the difluoroethoxy ketal but does not affect the stereochemical compositon of the mixed ketal. The differential behaviour of the element effect on product distribution together with the general stereochemical course of the reaction are consistent with the final step of the reaction being protonation of the carbanion that results from the nucleophilic attack on 1_. When a nucleophile as CN~ is employed, the reaction takes a different course. 3-cyano-3-chlorocyclobutanecarbonitrile (3), 1,3-dicyanobicydobutane (4) and 3,3-dicycanocyclobutanecarbonitrile (5) were isolated from the reaction mixture. -CN - 14 - CONFIGURATION!. STABILITY OF VINYL CARBANIONS DERIVED FROM MONO-SUBSTITUTED ACTIVATED ETHYLENES B.A. Feit and U. Melamed Institute of Chemistry, Tel-Aviv University, 69978 Ramat-Aviv, Israel R.R. Schmidt and H. Speer Faculty of Chemistry, Konstanz University, Konstanz, West Germany 2 1 Substituents at one carbon of 1.2-disubstituted activated ethylenes Y-CH=CH-Z 1 (Z,Y: CN.Ph; COgR.Ph; CN,OR; CN,NR2; COgR.NRg; COgR.SR; COgR.OR) , affect the configurational stability of the derived vinyl carbanion (V.C.) on the other carbon atom: H" "* H (-H+) ^ c = c^ c = c H^ x Z H^ ^ E A general approach was developed for studying the dependence of the configura- *"• H tional stability of V.C. derived from ^C = CCZ on the substituent Z, without any C=C: and CsC influence of a C2-substituent. The pure cis isomers H' -H u^ ^H were synthesized and were each reacted with Ph2C=O in presence of a base in various solvents at low temperatures: 1. Bo*e ^ ^Z D^ ^C(OH)Ph2 ,c=c " + P»>2C«0 2. CHCI3-H2O v „- c(0H)Ph2 H' ^Z l.z- CN CO2CH3 H —' H ~ The vinyl carbanion o'C=c-CN was con-|ri"gurationally stable, while n^^C-co cu isomerized completely. Experiments were carried out to test the involvement of addi- tion-elimination type reactions in formation of the isomerized reaction products. 1. B.A. Feit, U. Melamed, R.R. Schmidt and H. Speer, J.C.S., Perkin Trans. I, 1329(1981); Tetrahedron 37, 2143(1981) and references cited therein. - 15 - 0 NOVEL MACROCYCLIC IRON(II) COMPLEXES Schely Avramovici-Grisaru and Shalom Sarel The Hebrew University of Jerusalem 1 o We have shown earlier ' that pyridoxal isonicotinoyl hydrazones tend to chelate iron(II) both in vivo and in vitro to form red-brown crystals m.p. > 400°) of FeUO-bis-pyridoxal isonicotinoyl hydrazones (1_-2J in which the phenolic group, the double-bonded nitrogen and the oxygen atom of the carbonyl group participate in metal binding. They are noted for their enhanced affinity for ferrous ions, with rather moderate association constants (log K 8.67 to 5.74). We assumed that the binding constants of the ligands could be enhanced if they were more rigid, namely, if the two units of pyridoxal isonicotinoyl hydrazone in (JJ and (2) could be linked by a chain of five or more atoms to form a macrocyclic system. Towards this end we designed the use of iron (I I)-complexes Q.-2.) as templates for the production of the hitherto unknown macrocyclic complexes of structures (_3) and (4.) where X_ equals CHp-CHp, 0 and NH. The formation and properties of (3) and (4), and their possible conversion (.3), R=H; Y=C1, Br, I (4),R=C0CH3; Y=Cl,Br, I. into artificial enzymes3 by inclusion other metals such as copper, will be discussed. 1. C. Hershko, S. Avramovici-Grisaru, G. Link, L. Gelfand, S. Sarel, J.Ldb.Clin.Med., 98, 99 11981). • 2 S Avramovici-Grisaru, S. Sarel, G. Link and C. Hershko, J.Med.Chem., .... U98Z) 3* A E. Martel in "Metal Ions in Biological Systems", Ed. H. Sigel, Marcel Dekker Inc., 1973, Volume 2, p. 207. 1 - 16 - 0 D'U3up3iiD myyim ni'juDP r>mnVipVin jnoiyn 70 rnpinn maim ,yioV TQY'I ii3n ,i*3 ?PIV ,a»AP apy 07'9 np'm *"y ni'iVipVin in niaais nx'u n*3nyj U3i7pg"iip 7ei m'E>7 nn'aD '"y K'n ni'i7ip7in 7n niaDw n'TaV ini' ni!"fn nimin) ni'aiaiK'ViN nm7ip7in in niaow ni7apnn ia 'T Vy .npyin ma Vy nu'X' mVya ni'iVipVin-in niaaw VapV in'3 .(nn'Don nVn nainn n'jATiNn iaa3 Hi no iy .(irn'D nn»3D) np^inn HTDH VK maawn VE» ri'O'D m't»p "'y maAin nmn njiefKin naawn nnVwn Dy D"nDn nn'apn TVnnw '3an nn'ap '"y ni'naai? an .H3P13 ii'TVipVin in naaw Vw HTWP niysim yin '373 nuisn wvnnvn on nn'spn nu'ya nvnaDw ai ni'TVipVin manyn nuaV in'3B' UNXD HT3 U3UP3T1D .nniAlD ni'lDniN'Al JlTll'D 11131311 'Vya D"731'Yp313-n D'O3Up3TlPa n'i7i3K nxiapi D'Jiiy D'pyin D'nuB»n7 irn^D HTPR npaxiin nVia "VKV Vya ni'nV TIY ina .tpj'iy D'K3uai m'nn n'rnna n'n'3 naiAiia n'nVia nxiapV n3'3ii7 n3iP3B> n'73'mo .mnpn n'lVipVio in na3i» UTY'V n'ipp na'nan n'xnnV nisnx nixiapn nan Vy .V"3n niwiiV n'3npy D'3iy CH2=CH-(CH2)n-SiCl3*VV3 naan 'Vya 13N mniBP ni'iiaay ai 7ii3iym nmVipVin in niasw mx'V onVi3' nN pnaV niaawn ni3'K .nsip mxa ni'3n'nn3 nmviB' 'Vya nyxann ni'naaw ain manynn n"3a .mi' inx i?3i?p3iipniy VDD msnwn ni'iVipVin inn nnVipVm inn naawn iina n'n'D naiAn n'mapyai .nn'DP ;D'aVi9 '3W VB» iTxanoVN »"y n nmyn nsiwjoV ni3aV n'n in'3 HKT av&i .n'nVis n^iapV nnViaxn nxiapn VB» yAn ni'iT ni'in "'y nK»y3 IVNH niaiynn ITQ'N .D'pxin u->nov>n Vy nimap .(ATR) n'B'33n mmnn nw»e»a DUN NiB3'Na n'Bippnopsp "'yi D'JIK* n'Vn3 Vm 'DIP axnV y'Ann '3U313P l'Vnna niVapnn niniapn ni'naay am n^naDw pan n'U3Vnpn miviyi qpna ,inia'x' m n»i?ann nai ,'n3'iimn niniapn maiynV aiwn inn' IT n3'nan .innxiin TVnn '13 iin o*iymnnn 'na3B> . L-B nu'wa mVapnnn IVNV nni'na minun n'ymn n3'nan in n3'3yn 1x3 '9 Vy mpaV Q'3n'3n n"3U3iap 0'3'Vnn niyxnna n"ou3'P D"iVipVin-Vy o»3an ai '»in'B» VN*X3Uia IT n»m nu'wa niVapnnn ni'iVipVinn nisiynV .vtnn ,D'VV3in D'3nupVN O'VAynV D'a'3ina nV3i ni'UP3'P ni3iann n*»3an Vnn - 17 - 0 171* 7T1K .n'uon 'tin'77 innn (2) (3) 5 DIQ'PB p (i) 'n7n 7W nmpin n'XjionD-m *"y 7yi37 ixxinp ,2 mnja ni'7'3nop7Kn nnunn iVnoa nimyi ni'sxn 7713) unuji 70 m'JTDan niNxinn pi monyni a"j»a 'BUD uyuo (5-1 A) i7ti D'AI7N3NI» R ? njnnun nummn . mannn .KXIDH nmn mnnn rnaiAJi7 .2 mnya :nni?n 1. a. Z. Yoshida, Top. Curr. Chem., 4£, 47(1973). b. D. Lloyd, H. McNab, D.R. Marshall, J. Chem. Soc, Perkin, Trans. I, 1260 (1975). 2. a. R. Weiss, C.Priesner, H. Wolf, Angew. Chem. Inter. Ed.,18, 472 (1979). b. D. Lloyd, R. K. Mackie, G. Richardson, and D.R. Marshall, Angew. Chem. Inter. Ed.,20, 190 (1981). 3. U. Zoller, E.M.Burgess, R. Burger (Submitted for publication). - 18 - 0 PHOTOSENSITIZED ELECTRON TRANSFER REACTIONS IN ORGANIZED ENVIRONMENTS AS PHOTOSYNTHETIC MODELS Itamar Wiliner and Yinon Degani Department of Organic Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel Photosensitized electron transfer reactions (eq. 1) are currently of interest as a means of solar energy conversion and storage.*)2 A basic limitation of such reactions is the thermodynamically favoured recombination process of the photo- products. We have developed a series of charged interfaces i.e. SiO2 and Z1O2 colloids, micelles and surfactant vesicles as a means to retard the recombination reactions and consequently stabilize the photoproducts. 3>If In these interfacial systems electrostatic repulsive and attractive interactions of the charged photo- products with the charged interface control the recombination process. (eq. 1) A + D *J^* A" + D+ Kb To examplify this principle the photosensitized reduction of propylviologen- sulfonate, PVS° (.1), using Ru(bipy)|+ or a positively charged Zn-porphyrine as sensitizers and triethanolamine, TEOA, as electron donor is 10-15 fold enhanced in the negatively charged SiO2 colloid as compared to the similar reaction in a homogeneous aqueous phase. This enhancement is attributed to the repulsion of the reduced photoproduct PVST, from the charged interface to which the oxidized species, Ru(bipy)§+ , is bound. Consequently, the photoproducts are stabilized against recombination and high quantum yields are obtained. & (I) R = -CH2CH2CH2-SO3" (2) R = -CH, Another approach involves the inclusion of one photoproduct into a receptor site. Cyclodextrins have been used as macromolecular receptors. The photo- sensitized decomposition of HI (eq. 2) using Pd-porphyrin as sensitizer has been accomplished. In this system methylviologen, MV^+, (2) is a primary electron acceptor, and the reduced product, MVt mediates the formation of H2 in the presence of supported Pt catalysts. The oxidized product I2 is entrapped in the CD-cavity and allows the accumulation of H2 (the fuel). This system is a solar converting fuel cell. The potential utilization of charged interfaces and macromolecular receptors for solar energy conversion will be discussed. hv CD (eq. 2) 2HI » » H2 + I2-CD 1. M. Calvin, Ace. Chem. Res., 10_, 369 (1978). 2. I. Willner et al. in "InorganTc Reactions in Organized Media" ACS Sym. Ser. No.177 (1981). 3. I. Willner, J.W. Otvos and M. Calvin, J. Amer. Chem. Soc., 103, 3203 (1981); Proc. Natl, Acad. Sci. USA., 78, 5928 (1981); J. Phys. Chem., 85, 3277 (1981). 4. I.Willner and Y. Degani, J. cEein. Soc. Chem. Commun., in press~Tl982). - 19 - STEROIDAL LACTONES RELATED TO THE WITHANOLIDES FROM PHYSALIS PERUVIANA I.. M- Sahaia, H. E. Gottlieb3, A. B. Rayb, A. Alib, E. G1otterc and I. Kirsonc. Departments of Organic Chemistry and Isotopes, The Weizmann Institute of Science, Department of Medicinal Chemistry, Banaras Hindu University,. Varanasi, India, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel. Further investigation of the Varanas! variety of Physalis peruviana L. 1 (Solanaceae) led to the isolation of two new steroidal lactones (la) and (3) related to the withanolides. Physaloiactone B 3-0-g-D-glucopyranoside (la), an amorphous powder [a]n +3.7° is the first glycoside in this series, isolated so far. Although glycosidation of sterols is a common process in nature, all the withanolides in which &-elimination did not occur in order to give the common 2-en-1-one system, had the 3P-0H group in the free form and the oxygen function at C-1 as 1a-0H, la-OAc or 1-one. The withanolides and their relatives are the only group of natural steroids comprising compounds with the side chain a-oriented. Perulactone (2) isolated some time ago had the normal 173-oriented side chain which was however oxidized at C-28 (OH level),thus enabling the closure of a y-'actone. The recently isolated perulactone B, m.p. 217°C, [a]D +56.5° has the same type of this rarely encountered side chain, but 17a-oriented. In the oxidatcve processes of ring A, a further step was achieved, leading to the transformation of the 1a,36-diol present as the la- acetate in (2) into the 2-en-l-one system present in (3). The co-occurrence of steroids with a and 6 oriented side chains in the same plant suggests a common pathway in the first steps of the biosynthetic processes leading from a 2^-methylene-choiesterol type precursor to the various withanolides and related compounds. The structures assigned to compounds (la) and (3) are based on spectral analy- sis, mainly 1H and 13C NMR and, whenever necessary, on chemical transformations. (la) 27 (3) 1,.Recent Developments in Naturally Ocurring Ergostane Type Steroids", a review by I. Kirson and E. Glotter in J. Natural Products 44, 633, 1981 and ref. cited therein. - 20 - MARINE DITERPENES WITH A CEMBRANE SKELETON: STRUCTURE AND CHEMISTRY Diana Barkan, Shmuel Carmely, Ami ram Groweiss, Dorotha Czarkie, Yoel Kashtnan and Uri Shmuel i Department of Chemistry, Tel Aviv University, 69 978 Ramat Aviv, Israel We have investigated the crystal and molecular structures of several diterpenes, isolated from Red-Sea corals, with particular attention to the conformational aspects of the fourteen-membered cembrane ring which is common to these molecules. The crystallographic data and corresponding molecular diagrams will be displayed. Since several structures of related natural cembranolide diterpenes, found in other parts of the world, have been reported, a comparative conformational study has now become meaningful. In this context two graphical representations of the molecular conformations will be shown, in order to (i_) illustrate the relative torsional strains and (ijj show similarities and differences between the various conformations, which can readily be related to the positions of the functional groupsthat apparently determine the biological activity of these interesting molecules. The conformation of the cembrane ring is expected to influence the chemical behaviour of the above natural products. Indeed, in several cases to be illus- trated, it is possible to correlate the configurations and conformations, as observed in the solid and inferred fro»n NMR coupling constants, with the course of chemical reactions that take place. " —HHg - 21 - LATRUNCULIN, A MARINE MACROLIDE FROM THE SPONGE LATRUNCULIA MAGNIFICA Y. Kashman and A. Groweiss Department of Chemistry, Tel-Aviv University Ramat Aviv, 69978 Tel Aviv, Israel New fish toxins were isolated from the Red Sea sponge Latrunculia magnifica. A full structure determination of these toxins by spectroscopic methods, including new NMR techniques, was aided by an X-ray diffraction analysis of a crystalline deriva- tive of latrunculin-A. The Latrunculins exhibit a new class of 14 and 16 membered macrolides, to which the 2-thiazolidinone moiety is attached. Some of the biological activities will also be discussed. 1 - 22 - Identification of Several Chemotypes of Artemisia herba alba Asso From the Middle East. Ruth Segal, Ilan Feuerstein Dept. of Natural Products, School of Pharmacy. The Hebrew University of Jerusalem P.O.B. 12065 Avinoam Danin, Dept. of Botany, The Hebrew University, Jerusalem Artemisia herba alba (Compositae) known as the "desert wormwood" is characteristic of the steppes of the Middle East and North Africa, it is wide- ly used in folk medicine as an anthelmintic, for relief from coughing, against intestinal disturbances, colds, measles etc. A systematic investigation of the sesquiterpene lactones isolated from plants collected from various localities showed marked differences in the constitution of their sesquiterpene lactones as is depicted in the Table. Evidently there exist several chemotypes among the Artemisia herba alba species growing in this vicinity. The broad range of therapeutic effects ascribed to the plant may probably be explained by the existence of several chemotypes. Composition of Sesquiterpene Lactones in Various A_. herba alba populations. Site of Growth Sesquiterpene Lactone Reference 1. Sede Boqer herbolide A (1_) (0.003%) Segal et al. herbolide B (2) (0.02%) Phytochem.l6_, 1237 herbolide C (3) (0.002%) (1977). 2. Mizpe Ramon herbolide A ((1) (0.16%()) Segal et al. herbolide B ((2) ) (0.015%) Phytochem.in press herbolide C (3_( ) (0.0016%) deacetylherbolide A (4) (0.02%) herbolide D (5) (0.021) 3. Elat 4. Sinai llB-H-tatridin D (6) Gordon et al. J. 3-oxo-lle-H-tatridin D (7) Nat. Prod. 44, 432 lla-H-gallicin (8) (1981). ~~ 5. Ras El Hikma santonin (9) Khafagy et al. (Egypt) Planta Medica 20, 90 (1971). ~ OR 1 - 23 - THE RED BLOOD CELL AS A MODEL FOR STUDYING THE MECHANISM OF CITRAL TERATOGENICITY. I. Tamir and A. Abramovici Developmental Pathology Lab J. Casper, Pathology Department Tel-Aviv University, Tel-Aviv and R. Segal and I. Milo-Goldzweig The Dept. of Natural Products The School of Pharmacy The Hebrew University, Jerusalem The teratological effect of citral (3,7-dimethyl-2,6-octa- dienal) on chick embryo has repeatedly been reported. Since ci- tral was found to be potent hemolysing agent it was decided to use the red blood cell as a model for elucidating the mechanism of citral toxicity. By using various inhibitors it was demonstrated that citral hemo'ysis proceeds through oxygen radicals. Compounds which give rise to free radicals are known to induce teratological effects. It is suggested that this mechanism may be responsible for citral teratogenicity. 1 - 24 - A CONVENIENT SYNTHESIS OF THE AGGREGATION PHEROMONE OF TRIBOLIUM CASTANEUM AND T. CONFUSUM 11 2 Eli Breuer , Joseph Deutsch , and Philip Lazarovici 1 2 Department of Pharmaceutical Chemistry, School of Pharmacy, and Department of Zoology, The Hebrew University of Jerusalem Suzuki has shown recently that the structure of the aggregation pheromone of Tribolium mentionee The biological activity of the final product and of the intermediates, and their specificities will be reported. ACKNOWLEDGEMENT: We thank Elana Wiener for technical assistance in the syntheses. 1. T. Suzuki, Agrio.Biol.Chm., 44_, 2519 O980). 2. M. Julia, S. Julia, and R. Guegan, Bull.Soe.Chim.Frcm.Qey 1072 (I960). - 25 - Cordialin A and B, Two New Triterpenes from Cordia verbenaceae DC (Boraginaceae) V. Vande Veldea, D. Laviea, R. Zelnikb, A.K. Matidab and S. Panizzab The Weizmann Institute of Science, Rehovot, Israel Instituto Butantan, Sao Paulo, Brasil In a search for biological active compounds from brasilian flora, from the leaves of Cordia verbenacea , two new dammarane-type triterpenes were isolated: cordialin A (la) and B (II). Their respective structures were established by + comparing their PMR, CMR and MS. Compound la, C_QH ,0 • M 486, mp 112°C, UV 225 nm (e 13,540), IR 3400, 1670 and 1600 cm" , produced a monoacetate Ib, M+ 528. By using trichloroacetyl isocyanate with PMR monitoring, two esterifiable OH functions were detected, which based on various deductions were located at C-3 and C-<11. The hemiketal bridge was disclosed by two pairs of doublets at 6 4.31 and 4.15 for the 19-protons, and in the CMR by a signal at 6 98.68 for C-3. An llot-OH (eq) was established through a deshielding effect observed on 18-H, 6 3.1 (2.7 in Ib). The side chain is characterized by an a,B-unsaturated carbonyl and a gem-dimethyl substituted epoxide. Compound II C .H.-Or, M 490, mp 117°C, IR 3350 and 1625 cm , no UV max., was found to be closely related to cordialin A. The spectra of II differed from la only for the side chain signals (NMR and CMR). It had the 20-22 double bond 6 1.56 for the 20-Me compared to 2.1 in la, and a glycol system replacing t\ epoxide. No carbonyl was present. H HO'. II - 26 - SOME PROPERTIES OF THE PHOSPHOROTHIOLATE S-OXIDE INTERMEDIATE Yoffi Segal! Israel Institute for Biological Research, P.O.Box 19, Ness-Ziona 70450, Israel. John E. Casida Pesticide Chemistry and Toxicology Laboratory, University of California, Berkeley, CA 94720, U.S.A. The proposed phosphorothiolate S-oxides, 1, obtained on m-chloroperoxy- ~~ ""' (12) benzoic acid (MCPBA) oxidation of S-alkyl phosphorothiolatesv * ' and probably also on biooxidation activation is a very short living intermediate. Attempts to directly observe 1 were so far unsuccessful. Althouth the first products to be observed and isolated are phosphinyloxysulfonates, 29 Some properties of 1 could be derived on MCPBA oxidation in various alcohols. 2 (R'0)2P(0)S(0)R . 31 ~ Thus, P nmr monitoring of the oxidation reaction indicates that complete phosphorylation of the solvent occurs if the reaction is carried out in primary alcohols. These results are independent of the J>-alkyl moiety and the appropriate trialkyl esters are the ultimate products. Oxidation in sec- alcohols gives an almost 1:1 mixture of esters resulting froir phosphorylation by^ and the appropriate dialkyl phosphates from initial rearrangement of J. followed by alcoholysis. The latter derivatives are obtained almost exclusi- vely in tertiary alcohols. Pure dialkyl phosphates are also exclusive products on initial oxidation in aprotic solvents, followed by reaction with alcohols. 1. Y. Segall and J.E. Casida, ACS Symposium Series, 171, 337 (1981). 2. Y. Secall and J.E. Casida, Tetrahedron Letters, 23, 139 (1982). - 27 - ALKALI-CATALYSED OEPOLVlERISATION OF CELLULOSE IN THE PRESENCE OF ANTHRAOl'INONE Israel I. Ziderman and Janine Belayche Israel Piber Institute, P.O* Box 8001, Jerusalem 91080, Anthraquinone (AO) promotes early deli^ni^ication and stabilisation of cellulose during alkaline pulping of wood. Quantitative analyses of pulps1 indicate that cellulose-dissolution is accelerated in the presence of A0o Alkali-catalysed depolymerisation of hydrocellulose was studied at 97°C under nitrogen. In the presence of sodium anthraquinone-2-sulphonate (AMS), the rates of both the chain-propagated unzipping-reaction and the competing termination-reaction were lowered. Since the former reaction was inhibited to a greater extent than the latter, less dissolution of cellulose occured in the presence of AMS at this temperature. This result indicates that the mechanism hitherto advanced^ for oxidative stabilisation of collulosic chain-ends by coupling to the chemical reduction of AQ is probably incorrect,, The inhibitory action of AMS at 97°C is ascribed to its possible effect in diminishing the degree of ionisation of reducing chain-ends. As a possible mechanism for the accelerated dissolution of cellulose at pulping temperatures, it is proposed that AO promotes intra-chain scissions in cellulose, enhancing the dissolution of chain-fragments without unzipping. This degradative effect of AQ may be mediated by the formation of keto-cellulose and/or aldehydo-cellulose in a free- radical mechanism, involving the action of hydrogen peroxide that is formed in situ in the presence of AQO References 1. N. Vanderhoek, personal communication; Bo Kosikov et_ al_o, Paperi ja Puu-Papper p_. Tra_ 62_ (1980) 229. 2, W.Ho Algar et_ al_., Appita 33 (1979) 33; K, Ruoho and F, Sjostrom, Tappi 61 (1978) 87, — - 28 - rtovel Derivatives of b-Ethoxy-1 ,2-Dihydro-2,2,fr-Trimethylquinol ine (Ethoxyquin) and Their Biological Activities. E. Menachemoff, 0. Awerbuch and R. Haber. Abie Ltd., Pharmaceutical and Chemical Industries. CH CH20H A; R B; R = CONH, Ethoxyquin is an antioxidant, widely and mainly used as a preservative in livestock feed. Novel ethoxyquin derivatives (amides, N-glycosides, carbamates and ureides) were prepared and their biological activities investigated. Ethoxyquin and some of its new derivatives (like A and 8,) act like vitamin E under biological conditions. A model demonstrating such an activity and possible applications of the new compounds are di scussed. 1 - 29 - THE FLUORESCENCE OF THYROXI-FLUORESCEIN CONJUGATE AND ITS APPLICATION IN A DIAGNOSTIC IMMUNOASSAY FOR THYROXINE. Ariel Gaathon, B. Fridlender and Nurit Israeli Ames Yissura, Ltd. Jerusalem, P.O.Box 5577 Thyroxine, presumably due to its iodine content, has been shown to exert heavy fluorescence quenching upon flurophores chemically bound to it. Specific antibody binding to thyroxi-fluorescein (T4F) has been found to partially relieve this quenching (1). It is reported here that serum pro- teins, other than specific immuno-globulins, exhibit similar fluorescence enhancement, which can be removed by 8 Anilino-naphthalene-1-sulfonic acid (ANS). The presence of small (0.1%) quantities of non-ionic deter- gents enhances T4F fluorescence depending on the pH. The enhancement of Triton x 100 is shown to be up to 500% at pH > 12. We describe a useful application of Triton x 100 enhancement in a simple, short and precise fluoroimmunoassay system for the diagnostic determination of thyroxine in serum samples. The assay involves the use of 50 ul of serum, a release of thyroxine from serum proteins with thiomersal,sequential incu- bation with T4F and PEG facilitated double antibody percipitation. The fluorescence in the percipitate is determined in 0.1 N NaOH containing 0.2% triton x 100. The assay's performance, in the range of 30 nM up to 240 nM, is characterized by <6% precision, both inter and intra assay, a sensitivity of 8 nM and long-term stability cf the reagents. It has attractive potential for wide practical use. (1) Smith D.S., Enhancement fluoroimmunoassay of thyroxine, FEBS Lett., 77, 25, (1977). - 30 - A MODEL FOR THE GENERATION AND AMPLIFICATION OF OPTICAL ACTIVITY Jan van Mil, Lia Addadi and Meir Lahav, Weizmann Institute of Science, Rehovot, Israel; S. Sifniades, Allied Chemical Corporation, Morristown, N.J., U.S.A. During recent years we have been involved in research towards the generation and amplification of optical activity from achiral or chiral racemic molecules. See scheme. crystallization reaction —P., chiral products Using a family of diacrylates as a model system, we found that small quantities of chiral products, resulting from a topochemical photodimerization in the solid state, when reintroduced in a fresh crystallization of the monomer, retard the formation of the crystal phase from which they were generated, resulting in an excess of the second crystal phase. This phenomenon, which proved to be very gen- eral and very effective in the resolution of enantiomers, and which we have termed "The Reversal Rule", finds its origin in a stereoselective adsorption of the chiral additive on to the growing faces of the crystal stereochemically similar to it, thereby retarding its growth while leaving the second enantiomer almost unaffected.* However, due to the intrinsic properties of this adsorption mechanism, an amplification as we envisaged in the scheme cannot be achieved this way. We have recently found a system which, based on the same principle of additive effects, resulting in diastereomer like molecules, does lead to amplification in the way of the scheme.2 The crystallization of the nickel complex DL-e-amino-a-caprolactam (DL-ACL)(which crystallizes in chiral crystals) in the presence of small amounts of L-lysine, leads to an excess of the L-complex, which after hydrolysis and ring- opening of the lactam gives L-lysine? The mechanism of this process of direct amplification will be discussed in terms of ligand exchange leading to two diastereomeric impurities (D,D,L' and L,L,L') which interact selectively with D,D,D and L,L,L crystals respectively, the D,D,Lf leading to the stronger interaction and thus to stronger retardation. 1. J. van Mil, L. Addadi, E. Gati and M. Lahav, J. Amer. Chem. Soc. 104, 3429 (1982). 2. W.J. Boyle, Jr., S. Sifniades and J.F. van Pepper, J. Org. Chem. 4£, 4841 (1979). 3. J. van Mil, Ph.D. Thesis, Weizmann Institute of Science, (1982). 1 - 31 - INDUCED RESOLUTION OF a-AMINO ACIDS BY CRYSTALS OF a-GLYCINE GROWING AT THE INTERFACE I. Weissbuch, E. Gati, L. Addadi, Z. Berkovitch-Yellin, M. Lahav and L. Leiserowitz Department of Structural Chemistry, The Weizmann Institute of Science, Rehovot, Israel. Experiments in which one could perform an induced resolution by crystals of a-glycine growing at a solution/air interface will be discussed. These experi- ments are based on the changes in crystal habit induced stereoselectively on a- glycine crystals when grown from aqueous solutions in the presence of small amounts of DL mixtures of amino acids. In these experiments we exploit the intrinsic packing and conformational features of the glycine crystals (space group P2i/n); the glycine molecules form H-bonded layers in the ac plane via translation symmetry adopting a conformation such that one of its C-H bonds is parallel to the unique b axis. A mechanism involving the selective adsorption and occlusion of the enantio- merically pure impurities on the enantiotopic (010) and (OlO) faces of the plate- like glycine crystals will be discussed. The morphological changes and the proposed mechanism demand that in the affected substrate crystals, the DL impurity must segregate along the b axis during crystal growth; occluded D impurity should prevail at the +b half of the crystal, whereas the L impurity should prevail at the -b half. These predictions were experimentally confirmed by HPLC experiments involving chiral separation of amino acids (studies done in cooperation with Dr. S. Weinstein).2 The above experiments suggested that when such growing plate-like crystals are either floating on the solution/air interface or resting on the glass bottom of the beaker, the crystal will grow only along that b direction, corresponding to the (010) or (010) face, which is exposed to the aqueous solution. Furthermore, from the racemic mixture of a-amino acids, only the appropriate enantiomer will be select- ively adsorbed and occluded on this face. The opposite face which is in contact with air or glass will be hindered in growth. In such a manner, the glycine crystals grown in the presence of racemic mixtures of a-amino acids contain only one of the enantiomers. 1. I. Weissbuch, E. Gati, L. Addadi, Z. Berkovitch-Yellin, M. Lahav and L. Leiserowtiz, submitted for publication. 2. S. Weinstein, Angew Chem. Int. Ed. Z\_t 218 (1982). 1 - 32 - Racemic and Pseudoasymmetric (-) Dialkyl Methylphosphonates Isolation and NMR Studies A. Balan, Y. Segal 1 and A. Tishbee Israel Institute for Biological Research, P.O.B. 19, Ness-Ziona 70450, Israel. The P nmr spectra of bis - (+) - 2-butyl (1) and bis (+) - 3,3-dimethyl-2-butyl methylphosphonates (£) showed a 1:2:1 signal ratio attributed to four isomeric compounds: The d, 1 pair A and the two meso forms B, and C.. 0G«. 0G G R ? R QGR CH,— P = 0 0 = P - CH-, CH3- P = 0 0 CH3 3 k i 3 6GS OG 0G$ 0GR S (S,S) (R,R) ( r,R,S) (s, R,s) A _B _c G =^j 2-butyl £ } 3,3 dimethyl-2-butyl The two isometic meso compounds are each pseudoasymmetric due to the combination of four different substituents at the phosphorous atom and the C~ symmetry of the molecule. The same stereochemistry is well known for carbon compounds e.g. pentitols and pentaric acids. In accordance to their p nmr spectra a 1:2:1 isomeric ratio was also obtained by HPLC on silica gel. The separated fractions of (£) gave each a single peak in the 31P nmr (-30.1, -29.1, -27.5 ppm). The product from methylphosphonousdichloride and two moles of optically pure (+)-2-butanol had only one 31P nmr signal and one peak on HPLC confirming the above assignment. - 33 - CHIRAL DIFFERENTIATION BY P-(+)-HEXAHELICENE-7a7'-DICARBOXYLIC ACID DISODIUM SALT. RESOLUTION OF DNP-a-AMINO ACID ESTERS BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY Y.H. Kim, A. Balan, A. Tishbee and E. Gil-Av Department of Organic Chemistry The Weizmann Institute of Science, Rehovot, Israel It has been shown previously that silica gel, modified by electron withdrawing substances such as R(-)-2-(2,4,5,7-tetranitrofluorenylidene-9-nminooxy) propionic acid [R-(-)-TAPA] or riboflavin, permits effective resolution of optical isomers capable of charge transfer (CT) complexation with the chiral reagent on the statio- nary phase. We wish now to report on the extension of our studies to the use of electron donating compounds as the chiral CT complexing component on the silica gel. P-(+)-hexahclicene-7,7'-dicarboxylic acid was chosen as the donor-modifier, since helical polyaromatic molecules display relatively high stereoselectivity on CT complexation. The chiral support was prepared by coating silica gel with the disodium salt of tne above diacid, which is insoluble in organic solvents such as CH-Cl- and n-hexane. N-2-4-Dinitrophenyl (Dnp) derivatives of the isopropyl and/or methyl esters of Ala, Val, Isoleu, Phe and Phegly were resolved with n-hexane, containing 1-2% of isopro- panol, as the eluent. The resolution factors were generally higher than 1.1. The enantiomers of the methyl ester of Dnp-Leu were, however, not separated under the experimental conditions (room temperature, flow rate - 1 ml/min). Some tentative correlations between structure and chiral differentiation of the Dnp esters will be discussed. By a judicious choice of derivatives, chiral reagents and mobile phase composi- tion, it should be possible to develop the present approach into a general tool for the enantiomeric analysis of Dnp amino acids. Furthermore, such electron donor sup- ports should be of wide interest, for the resolution of many other classes of com- pounds, as many substances can be made strong electron acceptors by derivatization with reagents containing moieties such as di- or trinitrophenyl. - 34 - HPLC RESOLUTION OF ENANTIOMERS USING CHIRAL ADDITIVES IN THE MOBILE PHASE. EXTENSION OF THE METHOD TO COMPOUNDS OTHER THAN THE PROTEIN AMINO ACIDS By S. Weinstein Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot, Israel We have introduced recently new chiral additives to the mobile phase and 1 2 achieved efficient and sensitive HPLC resolutions ' of the enantiomers of all the underivatized protein a-amino acids. These additives are copper complexes with N,N-dialkyl-a-amino acids. For the enantiomeric analysis of a mixture of all the common amino acids, the analysis has to be performed in two stages: First, the mixture is separated into groups on a cation exchange resin, eluted and collected with volatile aqueous pyridine buffers, and the eluant is evaporated. Then the amino acids within the groups are separated into the D- and L-enantiomers on a reversed phase column with N,N-di-n-propyl-L-alanine and cupric acetate in the aqueous mobile phase. Subnanomole sensitivity is achieved by postcolumn derivati- zation with o-phthaldialdehyde and subsequent fluorometric detection. Proline is detected by postcolumn derivatization with ninhydrine. We are now in the process of extending the method to compounds other than the protein amino acids. Examples are: 1. a-Methyl-a-amino acids which have gained interest in the study of antibiotics, as enzyme inhibitors, in research on the origin of life and as constituents of organic matter from meteorites. 2. y-Methyl- glutamic acid, which is of interest for the study of the mechanism of certain enzymatic reactions. Y-Methyl-glatamx acid has two asymmetric carbon atoms and its two diastereoemrs were each separated into a pair of enantiomers. Application to various analytical problems is described. 1. E. Gil-Av, A. Tishbee and P.E. Hare, J.Amer.Chem.Soc., l_02_, 5115 (1980). 2. S. Weinstein, M.H. Engel and P.E. Hare, Anal.Biochem., 121, 370 (1982). 1 - 35 - ISOLATION AND ASSIGNMENT OF CONFIGURATION OF THE DIASTEREOMERIC tvans-CHLORO (N,N-DIMETHYL-D-PHENYLGLYCINE)(3-ETHYLCYCLOPENTENE) Pt11 COMPLEXES By P.A. Ramaiah and E. Gil-Av Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot, Israel Following previous work on the resolution of chiral racemic olefins via their diastereomeric Pt complexes, we now report on experiments with the title compounds (I). Each of the enantiomers of 3-ethylcyclopentene (II) can form with Pt two diaste- reomers, since each face of the double bond can coordinate with the metal, and rota- tion around the axis passing through the unsaturated carbons is hindered. Indeed, by HPLC of (I) on silica gel with n-C6H /Cf^CU/iPrOH (80/10/1), as eluent, 4 peaks were observed, corresponding, respectively, to the consecutively eluting compounds 14 3 4 I -I , with I and I overlapping partially. By liberating active II with KCN from 14 2 3 isolated complexes, I and I were found to contain R-(+)-II, and I and I S-(-)-II. 1 2 On standing in CHC1_, pure I and I were, respectively, equilibrated to a mixture of I4/!1 (1.5/1.0) and I2/I3 (2.0/1.0). As in the more stable diastereomer, the approach of the Pt to the double bond must be easier, the following assignment can be made for the configuration at C. and 1 2 3 4 C2: I -1S,2R,3R; I -lS,2R,3S; I -1R,2S,3S; I -1R,2S,3R. Analogous structures represent I2(1S,2R,3S) ^=5lI3(lR,2S,3S) NMR (6, ppm): CH2CH_3(t) centered at: I1 1.169; I4 1.009; I2 0.981; I3 1.197. The NMR data are in agreement with the downfield shift reported in the litera- ture for a methyl group close to Pt. 2 30 Pure S-(-)-II (1.2 mg) was obtained from I . Its [a] -130° ± 5° (c 0.100 in CC1.) confirms the calculated value given by Mislow for a sample of S-(-)-(II) synthesized from (-)-2-cyclopentene-l-acetic acid of known optical purity. 1. M. Goldman, Z. Kustanovich, S. Weinstein, A. Tishbee and E. Gil-Av, J.Am.Chem.Soc., 104, 1093 (1982. 2. KTMislow and I.V. Steinberg, ibid., 77, 3807 (1955). 1 - 36 - Correlation between Circular Dichroism and the Absolute Configuration in the 3-Alkylcyclopentene System. A. Ramaiah and E. Gil-Av Department of Organic Chemistry, The Weizmann Institute of Science and Aharon Gedanken Department of Chemistry, Bar-Ilan diversity. The circular dichroism and absorption spectra of (P.)-3-irethylcyclopentene was measured in the gas phase and we were able to assign the spectrum on the basis of ab-initio SCF calculations. *• The first two transitions were assigned as I! -* 3s Rydberg and a valence II •+• II*. it is well known that in solution the Rydbera transi- tions, undergo substantial blue shifts. Therefore any atteirpt to correlate CD and absolute configuration of olefins in solutions is subjected to the problem that the first two transitions might overlap and cause ambiguous conclusions. In order to determine whether both transitions are sensitive to the absolute configuration or not, we have measured the absorption and CD of S-(-)-3-ethylcyclo- pentene. The optically enriched compound was obtained by attacking the racemic olefin with an insufficient amount of (+) diisopinocampheyl borane. The a (observed) = -35° corresponding to the e.e. of 26%. The results show that both transitions are sensitive to the absolute configuration. References 1. M. Levi, D. Cohen, V. Schurig, H. Basch and A. Gedanken, JACS 102, 6972 (1980) 1 - 37 - THERMAL ACID-CATALYSED REARRANGEMENTS OF TRANS METHYL CHRYSANTHEMATE. Zeev Goldschmidt and Bernard Crammer, Department of Chemistry, Bar-Ilan University, Ramat Gan. Raphael Ikan, Department of Organic Chemistry, Hebrew University of Jerusalem, Jerusalem. Trans chrysanthemic acid is one of the degradation products of the insecticidal esters known as Pyrethrins. Heating trans methyl chrysanthemate (1) with 50% aqueous sulphuric acid in heptane at 130 C afforded after three hours two isomeric methyl esters of hexadienoic acid as the principle products and a mixture of unsaturated lactones. After 17 hours the labile methyl ester had disappeared and a mixture of methyl esters and unsaturated y- and 5-lactones were obtained. Finally after 48 hours the methyl esters were consumed and there remained only a mixture of unsatured y- and &-lactones. The mechanism of the thermal acid-catalysed rearrangements of (1) will be presented. Trans methyl chrysanthemate and the acid-catalysed products were found to have excellent plant growth retardant activity. COOCH 1 - 38 - THE FORMATION AftjD CRYSTAL STRUCTURE OF A 12+5JCYCL0ADDUCT Shalom Sarel, Nipon Wongvisetsirikul and Shmuel Cohen The Hebrew University of Jerusalem Activated vinyl cyclopropane (VCP) when properly substituted could act as a source of four electrons (2c+2ir) on cycloaddition with electrophilic olefins (supplying 2ir-electrons) to form adducts containing seven-membered rings, ([2+5Jcycloaddition), formally resembling I'ne "Diels-Alder Reaction". Unlike the latter, the 12+5]cycloaddition appears to be a multi-stage process, involving an initial electrophilic attack of the electrondeficient oiefin on exo-cyclic double-bond of the VCP to yield a zwitter-ionic species which then cyclizes to form the respective seven-membered adduct. This communication concerns the formation and the crystal structure (X-ray analysis) of a seven-membered ring containing adduct (2) resulting from [2+5Jcycloaddition between trans-isopropenyl-2,2-ethano-l-methylene-l ,- 2,3.4-tetrahydronaphthalene CD and TCNE at -20°C. Evidently the cyclopropane N ring-opening is coupled with 7-membered ring formation, accompanied by an inversion of configuration. The new bond-forming in the cyclization stage takes place from a direction opposite to cyclopropane-bond breaking. 1 - 39 - STEREOCHEMICAL EFFECTS ON MASS SPECTRAL HYDROGEN REARRANGEMENTS IN BICYCLIC DIONES UNDER ELECTRON IMPACT Joseph Deutsch and Miriam Chriki Department of Pharmaceutical Chemistry, The Hebrew University School of Pharmacy, Jerusalem, Israel. A study has been done to investigate the behaviour of diastereoisomeric compounds under electron impact. It is known that mass spectrometric hydrogen migrations are frequently observed for carbonyl and hydroxylic compounds and that one of the factors which influences the rearrangement is the distance between the migrating hydrogen atom and the heteroatom to which the hydrogen moves^»2. In our research a bicyclic compound, 1,1'-bicyclohexyl-2,2'-dione (I) is studied. The compound was prepared by oxidation of the corresponding diol and the crude product was measured by mass spectrometer. The mass spectrum was found to be dependent on the length of time the compound spent in the mass spectrometer. The greatest differences in the spectra obtained were the ratios between the relative abundances of the ions of m/z 97, 98 and the molecular ion at the m/z 194. Under the assumption that these differences were due to the presence of two isomers (meso and dl) experiments were done to separate the two diastereoisomers and to study their behaviour. The separation and the mass spectral behaviour of two pairs of diastereoisomers will be presented. l.T.Lesman and J.Deutsch, Organic Mass Spectrometry, 7^,1321-1327 (1973), 2.J.Deutsch and M.Chriki, Organic Mass Spectrometry, l_4_,482-484 (1979) - 40 - Fluorescent Thiol Labeling and Other Reactions with Bromobimanes; Glutathione Sulfide (GSG) by Edward M.Kosower ' , Necham^ S.Kosower* and Annette Radkowsky Department of Chemistry, Tel-Aviv University, Ramat-Aviv, Tel-Aviv, Israel, 69978, Department of Chemistry, State University of New York, Stony Brook, New York, USA 11794 and ^Department of Human Genetics, Sackler School of Medicine, Tel-Aviv University, Ramat-Aviv, Tel-Aviv, Israel 69978 Bromobimanes are extremely useful for fluorescent labeling of reactive thiols in biological and biochemical systems. The labeling is rapid at physiological pH and the products are normally very photostable. Monobromobimane is effective on intact cells while the positively charged monobromo-trimethylammonio- bimane is used for lysed cells such as red cell ghosts. The bis- bromobimanes can label or cross-link proteins, as well as lead to other unusual reactions due to the intervention of bridged sulfonium ion intermediates. The reaction of a bis-bromoethyl bimane with glutathione produces the new compound, glutathione sulfide (GSG). - 41 - TAUTOMERISM IN DIHYDRO-1,3,5-TRIAZINE SYSTEMS A.L. Weis Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot, Israel The first observation of tautomerism of alkyldihydrotriphenyl-1,3,5- triazineLiness (I) and definitive structural asassignmen: t of the tautomeric 1,4-(IA) and 3,4-dihydrocompound (IB) has been made. PhwR H IA R = Me, Et, Bu", Bu*, Ph 1 13 Spectral(IR, UV, H and C dynamic NMR) correllations have been investigated and experimental evidence concerning the tautomerism of IA and IB was shown to be temperature, solvent and concentration de^andent. Comparison with 2 tautomerism of 1,4- and 3,4-dihydropyrimidines will be done. 1. R.M. Anker and A.H. Cook, J. Chem. Soc., 1941, 323; L.S. Cook and B.J. Wakefield, J. Chem. Soc., Perkin Trans. 1, 1980, 2392; L.S. Cook, G. Prudhoe, N.D. Venajak and B.J. Wakefield, J. Chem. Research (S), 1982, 113. 2. A.L. Weis and F. Frolow, Chem. Commun., 1982, 89; A.L. Weis, Tetrahedron Lett., 1982, 449; A.L. Weis and F. Frolow, Heterocycles, 1982, 493. - 42 - Photochemical Behaviour of Biased Homo-conjugated Ketones: 2-Methy1spiro[5.5]undeca-l,3-dien-r-one Jakob Zizuashvili and Benzion Fuchs Department of Chemistry, Tel-Aviv University Ramat-Aviv, Tel-Aviv 69978, Israel Abstract: The title compound (2J was synthesized and its photochemically induced transformations were investigated. Interesting wavelength effects were registered and mechanistic pathways are put forward, as affected by the structural features of the homo-conjugated ketone (2). + "l.(CH20H)2/H 2.LAH 1 .3.H Scheme 254 nra 254 nm (25%) 310 nm (71%) (J)311 - 0.08 (I)338 •= 0.07 0 CH, 311 310 nm (13*) |J> - 0.016 350 nm (60*) (J)338 • 0.023 0 CH, - 43 - SURFACE EFFECTS ON CONFORMATION AND SPECTRA OF DIBENZOTROPONE ADSORBED ON VARIOUS MONTMORILLONITES Z. Grauer^, D. Avnir^, S. Yariv^ and L. Heller-KallaitC} The Departments of Organic Chemistry^ , Inorganic and Analytical Chemistry^ ^ (c) and Geologyv J , The Hebrew University of Jerusalem, Jerusalem 91904, Israel. As part of our study of surface effects on the photochemistry and photophysics of adsorbed molecules, we have investigated conformational electronic and vibra- tionic changes in dibenzotropone (DBT.r) adsorbed on montmorillonites. The electronic spectra of \_ in various solvents are all within the UV range. Shifts into the visible occur only in very strong acids, due to the formation of the aromatic planar tropylium cation 2_. Red shifts to the visible range, with a maximum at 380 nm were observed upon adsorption on various montmorillonites. The following monoionic montmorillonites were studied: Na+, Cs+, Mg++, Cu++, Fe+3, Al+3. The degree of shift is dependent on water content and on the polarising effect of the exchangeable cation on the water acidity in the interlayer space. Thus, the red shift was even stronger (down to 420-480 nm) in the Cu, Ni, Al and Fe montmorillonites, when subjected to heating (100°C) under vacuum, whereas Na, Cs and Mg montmorillonites remained unaffected. IR measurements showed the formation of a hydrogen bond between the carbonyl and the acidic hydration shell of the exchangeable cation. The positive aromatic moiety so formed is stabilized by ir interactions with the oxygen sheet of the clay. . The organic molecule assumes a planar conformation, and tends to orient parallel to the clay layers. X-ray diffraction studied showed that the basal spacings of the DBT-'clay associations, depend on the number of water and DBT sheets (one or two) ranging from 12.1 A* to 20.4 A*. The lower value represents a single water and DBT sheet, and the higher value two DBT and two water sheets. 1 - 44 - ORTHO LITHIATIONS OF ARENESULFINIC ACIDS. NEW METHOD FOP ELECTROPHILIC AROMATIC SUBSTITUTION Samuel Braverman and J.C. Martin Roger Adams Laboratory, School of Chemical Sciences, University of Illinois, Urbana, Illinois 61801. The ortho lithiation of various benzene derivatives using rr-butyllithium has been studied extensively in the past. Prompted by the recent results obtained on the ortho lithiation of arenesulfonic acids, we have investigated the ortho lithiation of arenesulfinic acids. HgX £-BuLi/THF 1) E H 55 > 2) HgX, -78 Treatment of p-toluenesulfinic acid with 2,2 equivalents of n_-BuLi in THF at -78° results in a fast and quantitative dilithiation of the acid to give the ortho dilithium derivative 2_, as indicated by nmr spectral evidence after quenching with D-O. Electrophilic substitution reactions ortho to the sulfinate group can be easily performed by direct addition of the electrophile to the THF solution of 2_. Desulfination of the substitution product and con- version to an arylmercuric halide (3) can be easily achieved by heating with mercuric halide salts. The arylmercuric halides _3.ca n be used as synthetic intermediates or can be protonated to the meta-substituted toluene 4. The use of the sulfinic acid group as a directing and activating group for aromatic substitution under mild conditions, coupled with its subsequent removal, as described above, represents a new and potentially useful method for the synthesis of substituted aromatic systems which are otherwise difficult to obtain. A number of other synthetic schemes based on the di- lithium intermediate 2_, and the chemical versatility typical to the sulfinate group will also be considered. 1. For a leading reference, see: G.D.Figuly and J.C. Martin, J. Org. Chem., 45 3728 (1980) . 1 - 45 - SKELETAL REARRflNGEMENT OF A 2,6-DITHIAADAMANTANE-2,2,6,6-TETRAOXIDE DERIVATIVE DURING THERMAL AND PHOTOCHEMICAL SULFUR DIOXIDE EXTRUSION Samuel Braverman, David Reisman, Meir Freund Department of Chemistry, Bar-IIan Unviersity, Ramat-Gan Dov Rabinovich and Felix Frolow Department of Structural Chemistry, The Weizmann Institute of Science, Rehovoth Recently, we have reported that bis-y-y-dimethy 1 alleny 1 sulfone undergoes a novel and facile carbanionic cyclodimerization to the 2,6-dithiaadamantane bis- sulfone derivative 1. Surprisingly, it was also found that compound 1_ shows a strong ultraviolet absorption at Xmax = 236nm with e^29000 in acetonitrile although none of its it systems are conjugated.2 In view of this observation, as well as the considerable recent interest in the pyrolysis of cyclic sulfones as a synthetic method for the preparation of cyclic and policyclic hydrocarbons , we have investi- gated the thermal and photochemical elimination of sulfur dioxide from disulfone 1^, H(D) -2S0, hv Direct irradiation of di thi aadaman tane 1_ in acetonitrile at 254nm results in the extrusion of only one molecule of sulfur dioxide, together with a double allylie rearrangement of the second sulfonyl group, and formation of the tricyclic sulfone 2. Although the spectral evidence was in accord with the assigned structure of 2_, un- equivocal structure proof was obtained by X-ray crystallographic analysis. In con- trast to the photochemical results, pyrolysis of compound 1^ at ca. 300° results in extrusion of both S02 groups and formation of the bicyclic hydrocarbon 3^, with essentially the same rearranged carbon skeleton as in product 2_. The question whether the first SO- extrusion, which is common to both processes, is preceded or followed by the skeletal rearrangement, as well as other mechanistic details will be considered. 1. S. Braverman, D. Reisman, M. Sprecher, D. Rabinovich and F. Frolow, Tetrahedron Letters 901 (1979). 2. S. Braverman, D. Cohen, D. Reisman and H. Basch, J.Amer.Chem.Soc.,102, 6556 (I960) 3. For a review see F. Vogtle and L. Rossa, Angew.Chem.Int.Ed.Engl. _18, 515 (1979). 1 - 46 - DYNAMIC NMR INVESTIGATION OF THE TAUTOMERISM IN DIHYDROPYRIMIDINES A.L. Weis and Z. Porat Department of Organic Chemistry The Weizmann Institute of Science, Rehovot, Israel Recently we reported the first observation of annular tautomerism in the 1 2 dihydropyrimidine systems , as well as the crystal structure of 1,4- and 1,6- dihydrotautomer of dihydropyrimidines and the factors involved in recognition 4 of such tautomerism . In order to obtain further information about this type of tautomerism, we have carried out: a) A dynamic NMR study in chloroform solutions. The calculated kinetic activation and thermodynamic parameters will be discussed, b) Solvent polarity dependence. Chemical shifts and relative populations of the tautomers have been obtained in different solvents at low temperatures; the relative concentration of 1,4-dihydrotautomer has been shown to increase with the solvent polarity, c) Concentration dependence on the rates of proton exchange was found to indicate the intermolecular character of the proton transfer. 1. A.L. Weis, V.P. Mamaev, Izv. Sib. Otd. Akad., 1975, 148; Chem. Abstr., 1976, 12179v; A.L. Weis, 8th Int. Congress of Heterocyclic Compounds, Graz/Austria, 1981, 469. 2. A.L. Weis, F. Frolow, Chem. Commun., 1982, 89. 3. A.L. Weis, F. Frolow, Heterocycles, 1982, 494. 4. A.L. Weis, Tetrahedron Letters, 1982, 449. - 47 - COMPLEXATION OF ORGANIC COMPOUNDS TO CYCLODEXTRINS - ARTIFICIAL MODELS FOR SUBSTRATE-RECEPTOR INTERACTIONS IN ENZYMES Zafrir Goren, Phyllis Dan and Itamar Wiliner Department of Organic Chemistry, The Hebrew University of Jerusalem Jerusalem 91904, Israel The activity of enzymatic reactions is attributed to unique interactions of the substrates with the enzyme receptor sites. The strong association of substrates to these receptors originates from precise fitness of the substrate to the receptor site. In addition remote functional groups of the enzyme protein backbone participate in the complexation process. We attempt to utilize cyclodextrins (CD) as artificial receptors mimicking the functions of enzymes. CD's are cyclic poly sugars composed of 6, 7 or 8 glucose units linked by a 1,4 glycoside bond (a, 3 or y-CD respectively). Their cyclic structure forms a cylindrical hydrophobic cavity surrounded by polar CH-groups. A variety of organic substrates associate with the CD-cavity by means of hydrophobic host-guest interactions.1*2 The association constants (Ka) are determined spectroscopically. We have examined the enhancement of the host-guest interactions by introducing substrate-receptor anchoring sites that function cooperatively with the hydrophobic cavity in the complexation process. For example, the association of ferrocene carboxylic acid (1) (Ka=1.3xlO2 M"1) is ca. 300 times stronger than that of ferrocene (2). This enhancement is attributed to the participation of hydrogen bonds between the substrate, (1_), and the CD-hydroxyl groups periphery. (1) R = -C02H (2) R = K B-CD Different aspects of participation of substrate functional groups in the complexation, and controlling the reactivity of these substrates by means of CD-receptors will be discussed. 1. W. Saenger, Angew. Chem. Int. Ed. Eng. Jj^, 344-362 (1980). 2. I. Tabushi, Ace. Chem. Res. 15, 66-72 (1982). - 48 - CONTROL OF PHOTOINDUCED ELECTRON TRANSFER REACTIONS IN POSITIVELY CHARGED CTAB MICELLES, DODB VESICLES AND ZrO2 COLLOIDS Yinon Degani and Itamar Wiliner Department of Organic Chemistry, The Hebrew University of Jerusalem Jerusalem 91904, Israel Photosensitized electron transfer reactions are of interest as a means of solar energy conversion and storage.1 We have examined the photosensitized reduction of anthraquinone-2-sulfonate (la) and (lb) in positively charged CTAB micelles and DODB vesicles. In these reactions, Zn-TPPyS°, (2), is used as sensitizer and cysteine as electron donor. The photoreduction of (La) in CTAB micelles and DODB vesicles is 5 and 10 fold enhanced as compared to the homogeneous aqueous phase. This effect is attributed to the stabilization of the intermediate photoproducts (eq. 1) against the thermodynamically favoured recombination by means of electrostatic interactions with the charged interface. The higher effect of the DODB vesicles is attributed to their higher surface potential. Substitution of (.la) with (lb) in CTAB micelles substan- tially enhances the quantum yield of AQHS" formation (W~= 0.26), a 26 fold enhancement as compared to the homogeneous solution. This enhancement is attributed to strong association of the electron acceptor to the micellar interface due to inforporation Of the counter ion into the micellar aggregate. Consequently, the recombination process (eq. 1) is effectively retarded by the electric potential. (eq. 1) Zn-TPPyS° + AQS' Zn-TPPyS (la) M+ = Na+ + + (lb) M = NH3-C16H33 2 A similar effect is achievedwith positively charged ZrO2 colloids. With this colloid the photoreduction of AQS", (la), and anthraquinone-2,6-disulfonate was accomplished with Ru(bipy)2(CN)2 as sensitizer and cysteine as electron donor. No reaction is observed in a homogeneous aqueous phase. The success in performing the reaction in the Z1O2 colloid is attributed to the stabilization of the photoproducts against the degrative recombination (eq. 2) that facilitate the subsequent oxidation of cysteine. Wf (eq. 2) Ru(bipy) (CN) + AQHST [ ZrO, Ru(bipy)9(CNU + AQS-? J Zr• O 7 9 1. I. Willner et al. in "Inorganic Reaction in Organized Media", ACS Sym. Ser. No. 177 (1981). 2. I. Willner and Y. Degani, Isr. J. Chem. in the press (1982). 1 - 49 - ANODIC OXIDATION OF ALLENIC HYDROCARBONS IN CHjCN James Y. Becker and Baruch Zinger Department of Chemistry, Ben-Gurion University of the Negev, Beer Sheva, Israel. The anodic oxidation of a variety of alkyl-substituted allenes, terminal and in- ternal ones, has been investigated in acetonitrile. All compounds studied were found to undergo 2e~ oxidation followed by nucleophilic attack by acetonitrile and water molecules, to form products containing at least two of the following function- al groups: C=C, NHCOCHj, C=0 and OH. The effect of various parameters (concentration, electrolyte, oxidation potential, temperature and anode material) on the electrooxidation of a model compound (1,2- nonadiene) has been studied and a general mechanistic scheme is presented and discussed. Under appropriate conditions (higher substrate concentrations, elevated potentials and in the presence of BF.~) heterocyclic compounds were formed, incorporating an allenic molecule with two acetonitrile ones. - 50 - EVIDENCE OF HYDROXIDE ION EXTRACTION IN THE PHASE TRANSFER CATALYZED ISOMERIZATION OF ALLYBENZENE Marc Halpern, Yoel Sasson and Mordecai Rabinovitz Department of Organic Chemistry and the Casali Institute of Applied Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel In many organic reactions requiring a base, the classical bases (alkali metal alkoxides, amides and hydrides) have been replaced by the more convenient aqueous sodium hydroxide in the presence of a phase transfer catalyst. The mechanism of such PTC/OH" systems has been the subject of much discussion. It is generally accepted that deprotonation of an organic substrate by the hydroxide ion occurs at the interface, and the resulting organic anion is drawn into the bulk organic phase by the catalyst for subsequent reaction. A second possible mechanism is extraction of the hydroxide ion into the organic phase by the catalyst followed by substrate deprotonation and reaction. We have investigated the base catalyzed isomerization of allylbenzene under PTC/OH" conditions. Examination of the dependence of the pseudo first order rate + R4N Br~ Na0H Ph-CH?-CH=CH7 ^ » Ph-CH=CH-CH, (trans and cis) 75 °,Toluene constant on stirring speed, catalyst structure, catalyst concentration, temperature, aqueous hydroxide ion concentration and catalyst counterion provides strong evidence for the applicability of the hydroxide ion extraction mechanism. Our results will be presented and the criteria for PTC mechanism determination will be discussed. 1 - 51 - Geometrically controlled diraerisation or acetone- G-methyl oxime, Uses for pyrrole synthesis Shimon ohatzmiller, KLiezer Baiiar and viamy Lidor Department of chemistry Tel-Aviv university, ctaniat- Aviv - fel-Aviv Lithiation of acetone O-methyl-oxime 1_ with n-Buli in IiIF / hexane at -6cj*C followed by reaction of lithiated 1[ with molecular iodine at -o^# LA,, (LJ MonolithiaUion of both 2 and %. at -0r3*-' .vud suosessive alkylation gives 4 and 6 respectively, -.cxd hydrolysis of 4 and 6 gives the pyrrole derrivaliives 2 mi<^ L respectively, i'hese O-wmet^l ethei^c can be hydrofseuoliced to the free pyri'oies. 1 - 52 - PREPARATION OF SUBSTITUTED PIPERIDINOCYCLOHEXANECARBONITRILES. A NEW VARIANT OF THE STRECKER REACTION. Asher Kalir, Jean-Marc Kamenka and Patrick Geneste Israel Institute for Biological Research, Ness Ziona, Israel and *Laboratoire de Chimie Organique Physique Appliquee, Ecole Nationale Superieure de Chimie, 34075 Montpellier, France. Aldehydes and ketones condense with secondary amines and hydrogen cyani- de to dialkylaminocarbonitriles ( Strecker reaction ). This reaction failed with 2-alkylated cyclohexanones 1, probably because of steric hindrance. HCN 7/ The desired compound £ has been easily prepared by cyanosilylation of 1_ and reaction of the substituted trimethylsilyloxycyclohexanecarbonitrile 6_ with an excess of piperidine in the presence of an acid catalyst. ~~ 0 I! R a + Me3SiCN The cyano group in £ could be exchanged by an aryl substituent to give derivatives of phencyclidine. 1 - 53 - NOVEL SYNTHESIS OF VTNYLALLENES AND 1,3-DIMETHYLENECYC3JOBUTANES TRHOUGH BASE- CATALYZED DIMERIZATION AND CYCLODIMERIZATION OF ALLENIC SULFONES Samuel Braverman, David Reisman and Meir Freund Department of Chemistry, Bar-Ilan University, Ramat-Gan The thermal cyclodimerization of allenes to 1,2-dimethylenecyclobutanes has been of long-standing interest. Recently, we have reported a novel base-catalyzed cyclodimerization of diallenyl sulfones to 2,6-dithiaadamantane 2,2,6,6-tetraoxide derivatives, and explained their formation by a "carbanion walk mechanism", in which an allenic a-sulfonyl carbanion initiates a series of four consecutive inter- intramolecular Michael additions, with final return of the negative charge to its original carbon. In continuation, we have tested this mechanism on monoallenic 1) n-BuLi/THF<.0° ^ _/ l)n-BuLi/THF . \ 2) Ho0 ?f 1 U Reflux H 1 Z = ArSO 2. 1 Treatment of YfY-dimethylallenyl aryl sulfone 1^ with n_-BuLi in THF at 0° re- sulted in dimerization to vinylallene 2, However, if the same reaction is run at reflux temperature instead, the expected cyclodimer _3 is obtained. Obviously, forma- tion of a 1,3-dimethylenecyclobutane requires a higher activation energy than the formation of 2,6-dithiaadainantane skeleton. Besides its mechanistic significance, both reactions are of considerable synthetic utility, especially after reductive desulfurization. For example, vinylallenes have been of particular interest recent- 2 ly due to their facile [1,5] sigmatropic rearrangement to conjugated trienes , while the synthesis of 1,3-dimethylenecyclobutanes nicely complements the thermal cyolodimerization of allenes. Finally, since allenic sulfones are readily obtained by [2,3] sigmatropic rearrangements of propargylic sulfinates, the above reactions are a very convenient approach to the title compounds. 1. S. Braverman, D. Reisman, M. Sprecher, D. Rabinovich and F. Frolow, Tetrahedron Letters, 901 (1979). 2. C.G. Knudsen, S.C. Carey and W.H. Okamura, J. Amer. Chem. Soc., 102, 6355 (1980) and references cited therein. For a general review on vinylallenes see, I.Z. Egenburg, Russ. Chem. Rev., £7 470 (1978). - 54 - THE SYNTHESIS OF NEW 3,4-DIMETHYLENETHIOLANE DERIVATIVES: POTENTIAL TETRAMETHYLENEETHANE PRECURSORS. Samuel Brave man and Meir Freund Department of Chemistry, Bar-Ilan University, Eamat-Gan, Recently, we have reported a facile synthesis of the novel condensed heterocycle l,l,4,4-tetramethyl-lH,4H-thieno[3,4- Scher,e l)Bro,CCl; 1) LAH.A1C1. •> 2) ra-CPBA I) 50 fCH OH 1) n-CFBA.O" 1) A H- / \ s It is noteworthy that conpound £ is separated from the tetramethyleneethane derivative £ by a mere sulfur dioxide bridge, and may therefore serve a suitable precursor for this elusive biradical intermediate. The effectiveness of the above scheme for the preparation of the title compounds will be compared with that of existing methods. 1. S. Braverman, M. Freund, and I. Goldberg, Tetrahedron Letters, 21^ 3167 (1980). 2. A.C. Talma, J.G.M. Goorhuis and R.M. Kellogg, J. Org. Chem., 45_, 2544 (1980) and previous references cited therein. - 55 - THE REACTION OF BENZYLIDENACETYLACETONE WITH BENZAMIDINE A.L. Weis and M. Bernstein Department of Organic Chemistry The Weizmann Institute of Science, Rehovot, Israel In a thorough reinvestigation of the condensation of benzylidenacetylacetone (I) with benzamidine (II) (S. Ruhemann, 1903) we have shown, that the initial product of the reaction is compound (III), which, depending on the condition of the reaction, may then be transformed into dihydropyrimidines, either (IV) or (V). 0 The mechanism of these cyclizations, the influence of the ratio of starting materials on the reaction course, the catalyst and solvents used as the reaction medium, the aromatization possibilities of the formed ring, and other factors which favour or preclude the formation of the pyrimidine nucleus, will also be discussed. This sequence of reactions enabled us to prepare the functionalized derivatives of dihydropyrimidines at position 5. - 56 - SYNTHESIS AND CRYSTAL STRUCTURE OF 2,4-DIAZA-6,7-BENZO-8-OXABICYCLO[3.3.1]-NONANES * j. * * A.L. Weis , F. Frolow , M. Bernstein and J. Fahima •V 4, Departments of Organic and Structural Chemistry The Weizmann Institute of Science, Rehovot, Israel As part of a study of convenient models for determination of structure and tautomerism in dihydropyrimidines, we attempted the synthesis of compounds of type Z_, where an ortho-hydroxy group was expected to stabilize the 1,4-dihydrotautomer by intramolecular hydrogen bonding. Using standard procedures for preparing dihydro- pyrimidines (condensation of ot,3-unsaturated carbonyl compounds 1_ with amidines 2_ in benzene with azeotropic removal of water), we isolated a colorless crystalline product in 80-90% yield. R=Me;ph HO Although the initial analytical data and parent ion peak in mass spectrum fitted that of the desired 3_, IR and NMR studies suggested the novel tricyclic bridgehead structure A_ for the product. This was confirmed by an X-ray diffrac- tion study. - 57 - THE FEACTION OF CARBENES WITH CTCLOHEPTATRIENE-Fe (CO) 3 COfTLEX Shlomo Antebi and Zeev Goldschmidt Department of Chemistry, Bar-Ilan University, Ramat-Gan Previously we have reported that derivatives of the cycloheptatriene-Fe (CO) , complex (CHTC) (1) undergo cycloaddition reactions with uniparticulate electro- philes such as tetracyanoethylene (TCNE), N-plenyl-triazolinedione (NPTD) and diphenylketene to give a variety of bicyclic compounds. Here we wish to report a simple approach for the preparation of bicyclo[5.1.0]- octadiene systems by cycloaddition of carbenes to CHTC. Thus the addition of dichloro- and dibromocarbene under phase transfer conditions resulted in a smooth conversion of CHTC to 2_ and _3, respectively. Also acylcarbenes generated from the corresponding diazo compounds by copper catalysed thermal reaction cycloadd to CHTC. However, while ethyl diazoacetate gave the expected product 4_ benzoy] diazomethane afforded a o,II-ally 1 complex. F« (COl ^ X=Y= CA 2 X=Y= Br 4 X= COOEt, Y= H 1 - 58 - A NEW INDICATOR SUBSTRATE FOR CLASSIFICATION OF NUCLEOPHILES. * Ehud Keinan and Zeev Roth Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot, Israel A qualitative classification of nucleophiles with respect to their interaction with ir-aHyl palladium complexes is suggested, based on regiochemical selectivity. The indicator substrate ± reacts in three different modes with various nucleophilic reagents: Nu Nu CN OAc Ph' Pd(PPh3)4 CN Nu This pronounced regioselectivity can be correlated to stereospecificity phenomena observed in these reactions. An explanation is suggested, based on the formation of unsymmetrical ir-ally! palladium complex as the active intermediate. 1 - 59 - REDUCTIVE ELIMINATION OF VICINAL OXYGEN FUNCTION WITH PALLADIUM(o). APPLICATIONS IN WITHANOLIDES INTERCONVERSIONS. * 1 E. Keinan , M. Sahai, and I. Kirson 1Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot Faculty of Agriculture, The Hebrew University, Rehovot A highly chemoselective method offered by organopalladium chemistry to reductively eliminate two vicinal oxygen functions, one of which is allylic. The reaction mechanism was investigated by means of NMR spectroscopy by which two defined intermediates were identified. Application of this process in natural products chemistry allowed highly efficient and useful interconversions of naturally occuring withanolides: Pd(PPh3)4 OH OH _ rr AcO OH 4-Acetoxy Withanolide E Withaperuvin C As part of the mechanistic investigation the same catalyst, was also used for stereospecific and regioselective amination of natural withanolides: OH I 1 •tra nnr« mpia 341302 merCU :Dj7iV 03-485774 : '"7U , 47100 mw nir1 6 .7.71 E. MERCK, DARMSTADT , WEST GERMANY • D^A 'inin ,nmy» J.C. BINZER , BOECKEL & CO. , Scientific equipment, Riele - Photometers for water testing and diagnostica • TH. GOLDSCHMIDT • iiy 71i'yi DI^'Y n"»yn ANKOR SCIENTIFIC EQUIPMENT & SERVICES LTD. TRACOR INSTRUMENTS Gas/Liquid Chromatography FINNIGAN MAT Mass Spectrometers WESCAN INSTRUMENTS Ion Chromatography ANALECT INSTRUMENTS FT-IR Spectrometers ALLTECH ASSOCIATES Chromatography Supplies JOBIN YVON INSTRUMENTS Raman Spectrometers Plasma Spectrometers BIOTRONIK GMBH Ami no Acid Analyzer r> O Ft 34'» GIVAIAVIM •", 1 IO? nniyn7 ltd CHEMICALS FOR LABORATORY AND INDUSTRY 36016 in • 624361-2-3-4."7D • 22 TUZTin TH • 66183 TEL-AVIV 66183 • 22. HARAKEVETH STR • TEL 624361-2-3-4 • PO B 36016 f DU'TU njmn '37 DWKU/Jll LABORATORY FINE LARGE VARIED IMPORT OF INDUSTRIAL IN ROW MATERIAL DELIVERY REAGENTS PER CUSTOMER SERVICE (RIEDEL-DE HAEN) CHEMICALS LOCAL STOCK ORDER TECHNICAL ADVISE • M/l*I7n \W numn1? nnnrn xiimn SPECIAL DISCOUNT FOR LARGE ORDERS iimicon Ultrafiltration 1 •• Microfiltration Columns Fixed Capacity Adjustable Columns Capacity Columns Small Scale Intermediate Scale Large Scale Acrylic Acrylic Acrylic Production Column Production Column Production Column Small Scale Large Scale Glass Glass Production Column aoi4°.T.n 26 ahniYiK 'm Production Column " ^^-. 3-2^66 Recorders for M"ya opmntu' r. an GOER; 6014 .-r.n 25 rrnin'riK 'm BBC Laboratory 62488 3i3N-7n SROWNBOVERi METRAWATT and Workshop 3-2266 D|77U 24821311370 111111 • 111 • i• 111 • • • • 111• 11• i • • • (Ii,;> 1 INORGANIC CHEMISTRY - 60 - LUMINESCENT SOLAR CONCENTRATORS FOR ENERGY CONVERSION Renata Reisfeld, Department of Inorganic and Analytical Chemistry, The Hebrew University of Jerusalem The geographical, seasonal and spectral distribution of the terrestrial solar energy will be described. The concept of non-tracking fluorescent concentra- tors and the mathematical background for collection and concentration of direct and diffuse light will be discussed. The single plate, multiple stacks and thin films doped by one or more colorants will be reviewed. The differences between inorganic and organic materials will be analyzed. A summary of spectroscopic data absorption, fluorescence spectra and decay curves of various inorganic ions and their suitability for fluorescent glass plates will be reviewed. Factors respon- sible for quantum efficiency will be discussed. Suggestions for new hybrid sys- tems will be made. - 61 - CHEMICAL REACTIONS OF UNSTABLE COMPOUNDS WITH METAL-CARBON BONDS IN AQUEOUS SOLUTIONS Dan Meyerstein Chemistry Depts., Ben-Gurion University of the Negev and Nuclear Research Centre Negev, Beer-Sheva, Israel Short lived transients with metal-carbon bonds have been suggested as inter- mediates in catalytic systems, e.g. Fentons reaction, and biochemical processes, e.g diol dehydratase. Pulse radiolysis is a convenient technique for studying rates of reaction of aliphatic free radicals with transition metal complexes yielding trans- ients with metal carbon bonds. LMn+ •*• LM(n+1)—CR The technique enables also the study of the chemical properties of the metal carbon bond formed. Reactions involving complexes of Cr(II), Cu(II), Cu(I), Fe(II) and Co(II) with a series of aliphatic radicals are reported. Examples of oxidative and reduc- tive heterolytic as well as of homolytic dissociation of the metal carbon bond will be presented. The specific rate of 3-elimination of hydroxyl groups was measured in several systems, e.g., LM-CH2C(CH3)2OH + LM-CH = CfCH^ + H20 and indications for g-hydride shift was obtained in some systems. Factors affecting the chemistry of metal-catbon bonds in aqueous solutions will be discussed. -1 - 62 - brriby no^ipon - nn niann !>«; o^p^iipa o^op^amp ipna TDinn !>y nnoa nt>K nn^A'!? IWK nnni^an nuiDnna pi Kt> laoa v^ naiAnn utnayaa nipnj irmiriNn *mi»aa .D'jn^ni oioipi ^n^ bis D>t>p>if ">"y vait>Ai>ai vai^Ainna heme -n n^iap no^nn t>e> nipn It - 63 - 0 REACTIONS OF IRON(II) PROTOPORPHYRIN WITH FREE RADICALS. A PULSE RADIOLYTIC STUDY. Yacov Sorek, Haim Cohen and Dan Meyerstein Chemistry Departments, Nuclear Research Centre Negev, and Ben-Gurion University of the Negev, Beer-Sheva, Israel The reactions of iron(II) protoporphyrin, Fe(II)L, with 'CH^CCH^OH, •CH(CH )OH and e were studied. The results indicate that the reaction with o aq •CH2C(CH,)2OH is too slow to be studied by the pulse radiolytic technique. Fe(II)L reacts with e to produce an unstable intermediate which is transformed by a aq c first order process into Fe(III)L. The reactions observed are probably (1) Fe(II)L + e" -*• Fe(I)L k = 7 x 109 M"1S"1 aq followed by 3 1 (2) Fe(I)L + H20 •*• Fe(III)L + H2 k = 4 x io s" Fe(II)L reacts with *CH(CH )0H radicals to produce a transient which differs from Fe(I)L probably described by 88 1 (3) Fe(II)L + •CH(CH3)OH •* Fe(III)L - CH(CH3)OH k = 4 x 10 M'V The latter transient decomposes by a first order process with k = 270 S" to yield Fe(III)L. The reaction observed is probably HO (4) Fe(III)L - CH(CH3)OH -^-> Fe(III)L + CH3CH2OH or (5) Fe(III)L - CH(CH3)OH -*• Fe(I)L + CH3CHO followed by reaction (2) which is faster. Analysis of the final products will discriminate between the later reactions. - 64 - 0 A STUDY OF THE MECHANISM OF FORMATION OF POLYMERIC SPECIES IN THE MASS SPECTRA OF PENTACARBONYLTRIMETHYLSILYL-ISO-CYANO- COMPLEXES OF GROUP VI METALS Miriam Cpjocaru and Jacob M.F. Goldschmidt Department of Chemistry, Bar-Ilan University, Ramat-Gan, 52100 The mass spectra of compounds having the generalized formula J RR R"SiNCM(CO)5 [R=H,Me ,Et,NMe2; R'=R"=Me,Et; M=Cr,Mo,W] all show signals due to the presence of peaks (RR'R"SiNCM)2 (CO)..- [n=l-10] and often far weaker signals due to (R'R' R" SiNCM)o (CO),_ [n=l-15]. similar phenomena reported in the mass spectra of J 15—n the hexacarbonyls of these metals have been ascribed to ion-molecule reactions (1). However, as preliminary experiments showed that the appearance of the dimeric species is restricted to quite specific conditions, the above mechanism seemed questionable. So, in order to understand the source of the polymeric species and the mechanism of their formation, we undertook a wide-ranging investigation of the conditions under which these ions are formed. The following parameters were varied systematically: inlet temperature, source temperature, method of ionization (electron impact and chemical ionization) and ionization potential. The changes in the amounts of the various species was followed quantitatively. The results of these experiments will be presented and discussed in detail. Contary to the earlier proposal, evidence supporting a chemical mechanism for the formation of the polymeric species, as outlined below, was found. The mechanism proposed is: l RR'^'SiNCMtCOg ~2—* RR R"SiNCM(C0)5_n (n=l chief species) 1 1 RR'R"SiNCM(CO^_n + RR R"SiNCM(CO)5_n, »• (R R R"SiNCM)2 (C0>10_n_n, . The most prevalent dimeric species formed by this route derives from n=l, n'*0. Of course the entire fragmentation pattern of this product and of the other species formed is observed in the electron impact spectra. (1) C.S. Kraihanzel, J.J. Conville and J.E. Sturm. Chem. Commun., 159 (1971), and references therein. - 65 - Intermolecular Vs. Intramolecular-Electron Transfer Reactions in Cobalt(III) pentaamine Coordinated to Pyridinyl Radicals H. Cohen, E.S. Gould, D. Meyerstein, M. Nutkovich and C.E. Radlowski Chemistry Departments, Nuclear Research Center Negev, Ben-Gurion University of the Negev, Israel and Kent State University, Ohio USA Recently several studies have shown that ortho and para substituted pyridines are good catalysts for reduction of Cobalt(III) pentaammine complexes by europeous ions. In order to explain this result the followinq mechanism was suggested : J 5NHJ + L (1) (2) h @ aq + 5NH4 + L Furthermore in systems where the organic ligand L is a pyridinyl ligand coordinated to a Cobalt (III) center via a carboxylate functional group the reduction of the complex involves reduction of the pyridinyl followed by an intramolecular electron transfer reaction, IET, from the pyridinyl radical to the Cobalt (III) center (4) We have investigated the reduction of four Co(NH~),-L (where L is a pyridinyl derivative) in order study structural effects on the rate of IET. Aliphatics radicals produced by the pulse radiolytic technique were used to reduce the carboxylate bound pyridinyl. Surprisingly only the bound free radical L.~ exhibed IET, k. = 4x10 S III and the other three Co (NH.J,-L; 2 3 reduced another parent complex Co (NH3)5L via the intermolecular electron transfer reaction : L (5) The origin for the different reactivity patterns is discussed. - 66 - 2 5 2 5 A NOVEL [Ru4(CO)?(y-CO) (n ,n ,Ti -INDENYL) (n -DIHYDROINDENYL)] CLUSTER Felix Frolow, Avi Efraty, and Amihai Eisenstadt Department of Organic Chemistry The Weizmann Institute of Science, Rehovot, Israel The reaction of indene with in boiling methylcyclohexane gave the expected dimer [(n5-indenyl)Ru(CO) ] as well as a second product which ultimately characterized as a tetranuclear cluster. The structure of this cluster and its novel features will be outlined and discussed. The tetra- nuclear cluster (1) consists of a triangulotriruthenium unit with Ru(4) being bonded to Ru(3). The near planarity of the Ru. skeleton is best illustrated by the slight displacement (ca. 0.07 A) of Ru(3) from the plane defined by the remaining metal atoms. The organic ligands in this cluster consist of seven terminal carbonyls, two symmetrical bridging carbonyls, three-way bridging (n2,n5,n2) indenyl, and n5-dihydroindenyl. According to the skeletal electron pair theory, the Ru(2)-Ru(3) bond in this cluster is formed by an interaction between a "filled donor orbital" on Ru(3) and a "vacant acceptor orbital" on Ru(2). This bond, where the electron density appears to be unevenly distributed, was found to be the longest metal-metal bond in the system. - 67 - PREPARATION OF SOME UNUSUAL y-CARBENE COMPLEXES OF RUTHENIUM Amihai Eisenstadt and Avi Efraty Department of Organic Chemistry The Weizmann Institute of Science, Rehovot, Israel The passing of an acetone-hexane solution of [Ru(CO) (n3-C,H,-) (n5-C H,.)] (mixture of isomers 1_ and 2) through a deactivated silica-gel column, gave an 1 3 5 unusual y-carbene complex of the type [Ru2(y-CO)(y-n Jn -CHCHCH2" (n -C H-)-] (3). This complex is formed by a process involving n3-allyl to y-n1,n3-allylidene transformation which implicates a-hydrogen transfer or elimination reactions. Similar transformations were also encountered with some substituted n3-allyl ruthenium derivatives. The stereochemical aspects of this reaction were ascertained by examining both then3-allyl substituents and isomers [endo(l) and exo(2)] effects on the course of the transformation and the nature of the products. The stereochemistry of products derived from this transforamtion were established, among other, by means of a comprehensive H and C NMR study. - 68 - 0 Complexes Of Lithium Salts With The Macrocyclic - polyether Dibenzo-14-Crown-£f. TJ. Olsher, E.R. Blout, Department of Biological Chemistry, Harvard Medical School. Boston, MA. 02115 05. Shoham, W.N. Lipscomb, Department of Chemistry Harvard University, Cambridge, MA. 02138 Since the discovery that lithium therapy has proven successful in some patients suffering from mania or biopolar disorders, there have been many studies on the effect of lithium in biological systems. The preponderance of these studies have focused upon (i) determination of the lithium concentrations in blood plasma and red blood cells of patients and normal individuals receiving such salts (ii) the mechanism of lithium transport across biological membranes, (iii) lithium salts as protein-denaturing agents, and to less extent (iv) the lithium coordinantion ability. Because we wish to understand better the lithium coordination and contribution of the "counter-ion" to many fundamental properties of such systems, i.e. structure, stability and selectivity, we undertaken a X-ray diffraction study of the crystal structure of the macrocyclic-polyether, Dibenzo- 1Zf-Crown-2f, complexes with LiNCS, LiCIO, and Lil. In all the complexes the lithium is, at least, penta- coordinated. The "counter-ion" effect has been elucidated. This study enables us to design lithium-selective-membranes for medical and industrial purposes. - 69 - 0 EXTENDED DONOR-ACCEPTOR MOLECULAR COMPOUNDS BETWEEN THIONES AND CHAINS OF BIS(IODINE) MOLECULES. F.H. Herbstein and W. Schwotzer Department of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel. Donor-acceptor molecular compounds between sulphur-containing organic molecules and single molecules of bis(iodine) are well known1'2. From preparative work and crystal structure determinations we find that there are two series of such molecular compounds containing more than one bis(iodine) per donor molecule, the known compounds constituting the first members of the two series. Unsymmetrical Chains Symmetrical Chains dithizone**I_ merocyanine#l*merocyanine 4 1 etu*«(I2)2 etu«I2'I2»I2»etu i2 dithizone»I «I 'I,,»I «I IL I I Z Z * dithizone is 1,5-diphenylthiocarbazone; etu is ethylenethiourea We find an approximately hyperbolic relation between d(S—I) and d(I—I) (in the I2 molecule directly linked to S). In the strongest interactions d(S 1) a. 2.49 A, approaching the covalent bond distance of d(S—I) = 2.37 A; concomitantly the bond distance within the iodine molecule linked to S is lengthened to ^ 3.2 A (in gaseous I2 dp—I) = = 2.66 A, while the van der Waals diameter of iodine is ^ 4.2 A). Thus + forms of the type RSI (In)~ must be major contributors to the overall resonance structure. References: 1. 0. Hassel. "Nobel Lecture" in Chemistry 1963-1970 (Nobel Lectures), Elsevier, Amsterdam (published 1972). 2. G.Y. Chao and J.D. McCullough, Acta Cryst. 13, 727-732 (1960). 3. M. Bois-Enghien-Peteau, J. Meunier-Piret and M. van Meerssche, J. Chim. Phys. Phys.-Chim. Biol. 65, 1221-1226 (1968). 4. See J.W. Bransford and E.A. Meyers, Cryst. Struct. Comm. 1_> spph (&1-1Q2 (1978) for the analogous Ph3PS—O2K— 3 Structure. 5. F.H. Herbstein and W. Schwotzer, Angew. Chem. Intl. Ed. Engl. 2\_, 219 (1982). J - 70 - 0 URANIUM IN APATITES. A. Givan, I. Mayer and L. Ben-Dor Department of Inorganic and Analytical Chemistry Hebrew University, Jerusalem, Israel. Uranium containing apatites were studied in order to examine the location of uranium in the apatite lattice. This project was initiated in connection with the possible exploitation of uranium from Negev Phosphates. Ca^PO )_0H (HA) and Ca5(P0 ,C03)_(OH,F) (CA) were prepared in the presence of various amounts of ura:-' nium. The molar ratio of U/Ca in the initial solution of HA ranged from 0-10.5%. EPMA analyses of the solid phases have shown a homogeneous distribution of U, P and Ca up to U/Ca ratios of 2.1% in the initial solution. XRD patterns of apatite containing these U/Ca ratios were of single phase; above this ratio uranium concen- trated in a different phase. Uranyl ions in the apatite matrix could be identified by the similarity of their emission spectra to U02 on other phosphate matrices. Assignment of Raman and IR bands in the vibrational spectra of HA and HA containing 1% U was made on the basis of functional groups. Carbonate apatites were prepared with initial U/Ca ratios of 0, 0.02 and 0.08%. Activation analysis showed the uranium concentration of the compounds to be 0.025 and 0.1%.XRD patterns of the compounds heated to 300C were similar to what is known for CA. At higher temperatures the decomposition of CA was facili- tated by the uranyl ions. Emission spectra of CA showed that unlike in the case of HA matrix, UCL emission in CA disappeared when heated to 100 C. This sug- gests a different bonding of U0- in CA. J - 71 - Low Temperature Synthesis of Chalcogenides N. Yellin Soreq Nuclear Research Center, Yavne, Israel Chalcogenide material of very high purity(>99.9999%) are essential for the production of optoelectronic devices and nuclear detectors. The classical synthesis of such materials is carried out at temperatures above the melting point of the compounds, >1000°C, which involves impurity (e.g. Si) diffusion from the quartz ampoule walls into the material. In the case of mercury chalcopenides, high pressures develop and occasional explosions of the charpe ampoule are unavoidable. In the present work synthesis of tellurides and selenides of Hg, Cd, Pb and Sn at temperatures considerably below the melting point of the compounds was studied. The reaction went to completion within a few days. CdTe single crystals grown from charges prepared by this method showed very high resistivity and nuclear radiation detection, indicating a very low residual impurity concentration in the material. J - 11 - ON THE DIFFERENCE IN THE OXYDATION OF 1,4,7 TRIACETATE-1,4,7 TRAZACYCLONANE NICKEL(II), IN AQUEOUS SOLUTIONS, BY HYDROXYL RADICALS AND ELECTROCHEMICALLY. Efrat Fuchs, Haim Cohen, Karl Wieghardt and Dan Meyerstein Chemistry Departments, Ben Gurion University of the Negev, Nuclear Research Centre Negev, Beer-Sheva, Israel and Ruhr University, Bochum F.D.R. The oxidation of 1,4,7 triacetato 1,4,7 triazacyclonane nickel(II), Ni L, by hydroxyl radicals and electrochemically was studied with the hope of obtaining Ni La new relatively stable strong oxidizing agent in aqueous solution. Stabi- lization was expected in analogy with Ni EDTA, and as tertiary amino groups as ligands are relatively stable towards oxidation and as tervalent tetraazamacrocyclic nickel complexes are stabilized by ligation with anions. The results indicate that oxidation by hydroxyl radicals indeed yields Ni L however the latter reacts with oxygen k TTT = 30 M S , and seems to be a Ni L+02 slugish oxidizing agent though it is a powerful oxidant, see below, and does not oxidize, iodide and ferrocyanide. Electrochemical oxidation was not successful. Although there is a one electron oxidation peak. (E « 1.05V vs. Ag(Ag C£), there is a second oxidation process with a redox potential very close to the first one, that produces a different oxidation product. This product has a different spectrum, and is considerably less stable than the tervalent nickel produced by OH radicals oxida- tion. Probably the electrochemical oxidation product is a Ni(IV) complex. The results thus again point out that electrochemical redox processes often differs from those caused by free radicals as electrodes might act as a several electron redox reagent. - 73 - EFFECT OF METHYLATION ON THE PROPERTIES OF 1,4,8,11 TETRAAZACYCLOTETRADECANE NICKEL(I) IN AQUEOUS SOLUTIONS H. Cohen, G. Ginzburg*, N. Jubran and D. Meyerstein Chemistry Departments, Nuclear Research Centre Negev and Ben-Gurion University of the Negev, Beer-Sheva, Israel The monovalent nickel complexes NiL (where L.. = 1,4,8,11 tetraazacyclo- tetradecane, L2 = 5,7,7,12,14,14 hexamethyl 1,4,8,11 tetraazacyclotetradecane, L, = 1,4,8,11 tetramethyl 1,4,8,11 tetraazacyclotetradecane and L. = 1,4,5,7,7,8, 11,12,14,14 decamethyl 1,4,8,11 tetraazacyclotetradecane) were prepared by electro- chemical and pulse radiolytic technique (reduction by e~ or CO^). The redox 2+ + aq / potentials for the NiL /NiL are < -1.6V, -1.40V, -1.15V and -0.95V vs. SCE for L = L-,L ,L and L. respectively. NiL1 and NiL9 are short lived in aqueous solutions, tj < 1 min whereas t, (NiL_) ~ 30 min at pH 12 and tt (NiL.) > 100 hours in neutral and alkaline solutions. The absorption spectra of the monovalent complexes consist of a strong band in the near U.V., A nn.(e M~ cm" )375(4.5xlO ); 380(3.6x10^); 353(3.1x10 ) and 335(3.6x10 ). The specific rates of reaction of NiL- with several oxidants are summarized in the, table. (The results for NiL* are from Tait et al., Inorg. Chem. 1976, 15, 934.) NiL + NiL NiLx 2 4 7 7 2 N20 3.2 x 10 3.9 x io 8.3 x io < O.I 9 7 °2 2.5 x 109 1.6 x io 1.6 x 109 4 x 10 + 6 5 5 4 Co(MH3)^ 6.2 x io 1.9 x io 8 x 10 1.7 x 10 8 8 Ru(MK-)|+ 6.4 x io 3.8 x io 4 .9 x 107 3 x 1O7 J D + The reactions with O_, Co(NH_)6 and Ru(NH3)* are suggested to involve single electron transfer processes whereas those with N_O are believed to involve an 3+ oxygen atom transfer yielding the respective tervalent nickel complexes. NiL. was indeed observed as the product of the reaction. The origin of the effect of methyl substitution on the properties of the mono- valent nickel complexes with 1,4,8,11 tetraazacyclotetradecane is discussed. *Dr. Gregory Ginzburg deceased August 5th, 1981. CHEMICAL CATALYSIS J - 74 - CATALYTIC HYDROGENATION AND TRANSFER HYDROGENATION REACTIONS IN MULTI-PHASE SYSTEMS Jochanan Blum Department of Organic Chemistry t The Hebrew Universityt Jerusalem, Israel Several metal catalyzed hydrogen-transfer processes proved to be more efficient and more selective under multi phase - rather than under homogeneous - conditions. In the presence of a quaternary onium salt, excess triphenylphosphine, an aromatic solvent and aqueous sodium formate, RhCl(PPh-), promoted transfer reduction of saturated ketones and nitro-compounds to give carbinols and amines, respectively. Under similar conditions (90°C), PdCl2(PPh,)2 catalyzed both the selective transfer- hydrogenation of a,g-unsaturated ketones and the hydrogenolysis of aryl bromides. The latter process could be carried out under even milder conditions (<70°C) when a mixture of benzyl alcohol and aqueous sodium hydroxide was used as hydrogen donor. The mildest conditions for hydrogen transfer from aqueous sodium formate could be achieved by utilizing 10% Pd/C, benzene and a mixture of 1:1 molar ratio of the formate and water. At 30 C smooth reduction of aromatic nitro-compounds, olefins and acetylens took place. The alkynes were initially converted into the respective cis-alkenes. Perchloro- and trichloro-methyl-compounds underwent selective hydro- dehalogenation. Alkyl phenyl ethers cleaved to give phenol and alkanes, while benzyl esters yielded toluene and the respective sodium carboxylate. Aqueous RhCl, was shown to give dichloroethane-soluble RhCl," by addition of methyltrioctylammonium chloride. The system proved to be a powerful hydrogenation catalyst for alkenes, alkynes and arenes at room temperature and sub-atmospheric pressure. The reduction of disubstituted aromatic compounds was shown to give almost selectively ais-disubstituted cyclohexanes. - 75 - 0 FORMATION AND REACTIVITY OF RUTHENIUM CARBOXYLATE COMPLEXES Michel Rotem and Youval Shvo Department of Chemistry* Tel-Aviv University, Tel-Aviv 69978, Israel Ruthenium carboxylates of the structural formula [Ru(C0)2(RCO2)]n are known only in the polymeric form (R^.CH^Et.n-C^ig)1. They are insoluble amorphous solids ob- tained by reacting Ru3(CO)i2 with carboxylic acids, which depolymerize upon reacting li2 with CO or other ligands (CH3CN,C5H5N, phosphines, arsines) c0 [Ru(CO)3(RCO2)] Ru3(C0)i2+RC02H —>- [Ru(CO)2RCO2]n L [Ru(CO)2(RCO2)L]2 We have found that a hitherto unknown ruthenium benzoate complex is obtained by reacting Ru3(C0)i2 with benzoic acid. Elemental analyses, l'r and nmr spectral data, as well as chemical transformations support a molecular formula [Ru(CO)2(PhCO2)]2. It is a coordinatively unsaturated stable complex which has no analogy in the ruthenium alphatic carboxylete series. The results of a brief investigation d'f its chemistry is outlined below. [Ru(CO)2(CH3CO2)]n PhCO2H| lcHl 3CO2H [Ru(CO)2(PhCO2)]2[Me2CO] SP^ [Ru(CO)2(PhCO2)]2 -** [Ru(C0)3(PhC02)] 2 NMe3l 1 —*• [Ru(CO)2(PhCO2)NMe3]2 << Ru3(C0)12+NMe3+PhC02H In variance with the behavior of the alphatic complexes [Ru(CO)2(PhCO2]2 has no tendency to polymerize. Our preliminary study of the catalytic reactivity of this class of complexes in organic transformation led to the following results: a. In the presence of phosphines, [Ru(CO)2(PhCO2)]2 is an excellent hydrogenation cat- alyst of ketones (1800 turnovers in 7.5 hours). b. The following catalytic reaction was observed: R u co PhCsCPh+RCO2H , a( hfr, PhCH=C(OCOR)Ph + Ph2C=CHOCOR 140° cis + trans The above reaction was carried out with benzoic and acetic acids: Ru3(C0)i2 can be replaced with the corresponding carboxylate complexes. Of special interest are the rearranged products - 1,1-diphenyl vinyl esters. References: 1. 6.R. Crooks, B.F.G. Johnson, J. Lewis and I.G. Williams, J. Chem. Soc. A, (1969), 2761. 2. H. Schumann, J. Apitz and J. Pickardt, J. Orgmet. Chem. 128, (1977), 253. - 76 - 0 FORMATION OF NEW C-C AND C-0 BONDS IN A HOMOGENEOUS CATALYZED ORGANOTIN COUPLING REACTION . I. PRI-BAR - Nucluar Research Center-Negev, PO.Box 9001 Beer-Sheva. J.K.STILLE - Department of Chemistry, Colorado State University Fort-Collins, Colorado 80523 USA. The palladium catalyzed reaction of oC-halodetones with tributyl- allyltin to give allyl substituted oxiranes and their rearrangement products has been reported to take place under vigorous conditions(1) (100°C, 20 hours), because this reaction with tin reagents apeared to be promising method for th« generation of C-C bond a study of the utility and scope of this reaction was undertaken. A variety of h^loketones or haloaldehydes were found to react with acetonyl- or allyltin reagents to give good yields of cyclic ethers. Oxiranes, oxentanes and tetrahydrofurans can be obtained under mild reaction conditions. The palladium catalyzed reaction is general for haloketones or haloaldehydes but only tin reagents containing readily transferable organic groups such as allyl and acetonyl react too give cyclic ethers in good yields (eq. 1). 0 X 0 2 \ Rl-C-(CH22))n.CHR. + (i) 63°C c y RA n = o,l,2 R1* H, alkyl, phenyl R3= alkyl, H" R2= H, alkyl = allyl, acetonyl The use of an optically active palladium catalyst containing monophosphine ligands gave a small enanthiomeric excess (up to of chiral oxiranes from <* -haloketones. The mechanism of the reaction apears to involve addition of the organotin ligand to the carbonyl forming a new C-C bond followed by palladium catalyzed cyclization of the tin alkoxides to form the new C-0 bond . (1) Kosugi,M.; Arai,H.; Yoshino,A.; Migita, T.,Chem. Lett. 1978, 795 - 77 - 0 PALLADIUM CATALYZED REDUCTIONS WITH GROUP IV A HYDRIDES E. Keinan*, P.A. Gleize, N. Greenspoon Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot, Israel. Trialkyl tin hydride was found to serve as an efficient hydride donor in very mild and chemoselective, palladium catalyzed reductions: 1) Conjugate reduction of activated olefins: Bu3SnH Pd(PPh3)4 2) Chemoselective reduction of allylic carbon-oxygen single bond: OAc CHO OAc Bu,SnH Ph^^CN Pd(PPh3)4 Both reactions are non-radical processes. The yield is significantly improved when a radical scavenger is introduced to inhibit undesired side reactions. The chemo and regioselectivity is demonstrated by useful transformations in the Withanolide series. 3) Polymethyl-hydrosiloxane (PMHS) was found to be even more chemoselective than Bu^SnH: 0 Bu3SnH Ph- H Ph Cl Pd(PPh-) PMHS - 78 - \ CATALYTIC OXIDATIVE COUPLING OF ALCOHOLS WITH Ru3(C0)12 Y. Blum, Y. Shvo and M. Kam Department of Chemistry, Tel Aviv University, 69978 Tel-Aviv, Israel n tne The catalytic oxidative coupling of alcohols to esters with Ru3(C0)i2 i presence of a hydrogen acceptor (A) has been recently descirbed by us1-5. Ru3(C0)12 2RCH20H + 2A — ^ RCO2CH2R + 2AH2 Kinetic studies reveal a two-step process; aldehyde was detected as an intermediate: 1. RCH2OH + A »- RCHO + AH2 2. RCHO + RCH2OH + A —*- RCO2CH2R + AH2 An alternative ester forming step viz. a Tishchenko reaction (eq.3) was ruled out \ with the aid of several experiments. 3. 2RCHO *- RCO2CH2R. This is an interesting point in view of a recent report which claims that transition metal complexes do catalyze the Tishchenko reaction.4 Detailed kinetic studies reveal that both the aldehyde and ester forming steps, which were monitored separately, are dependent on alcohol concentration. However, neither of the above steps depends, on the acceptor concentration. Such a behavior indicates that the H-transfer from metal to acceptor is faster than the dehydrogena- tion of the alcohol substrates; the rate determining step must therefore be associated with the latter process. It was established that hydrogen addition to acceptors such as diphenylacetylene, chalcone and maleic anhydride is an irreversible process. It was also noted that with alcohols having low reduction potentials, ester formation is incomplete, due to fast oxidation of alcohols to aldehydes which generates a final alcohol deficiency (see eq.l and 2). To overcome this problem we have designed a reaction system employing an H-acceptor which acts reversibly (eq.4 and 5). Ru3(C0)12 4. RCH2OH + cyclohexanone ^ ••- RCHO + cyclohexanol Ru3(C0)12 5. RCHO + RCH2OH + cyclohexanone >- RCO2CH2R + cyclohexanol Reaction 4 is an equilibrium process catalyzed by Ru3(C0)12. It controls, during reac- tion, a constant ratio (RCHO)/(RCH2OH) thereby allowing reaction 5 to proceed quanti- tatively. Since cyclohexanone has lower oxidation potential than most aldehydes, it was used as a solvent. A peculiar feature of this reaction is the requirement of a catalytic quantity of diphenylacetylene to prevent deposition of ruthenium mirror. References 1. Y. Blum, D. Reshef and Y. Shvo, Tetrahedron Lett. 22_(1981) 1541. 2. Y. Shvo, Y. Blum and D. Reshef, J. Organomet. Chem. 226_ (1981) C21. 3. Y. Shvo, Y. Blum and D. Reshef, J. Organomet. Chem., in press. 4. T. Ito, H. Horino, Y. Koshi ro and A. Yamamoto, Bull. Chem. Soc, Japan 55 (1982), 504. J - 79 - 0 THE APPLICATION OF PALLADIUM(O)-DIISOCYANIDE MATRICES IN THE HETEROGENEOUS CATALYTIC HYDROGENATION OF ALKENES AND ALKYNES Avi Efraty, Irene Feinstein-Jaffe, and Marcus Segal Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot, Israel 3 5 The reactions of 4,4'-diisocyanobiphenyl with [Pd(n -C3H5)(n -C5H5)] and [PdCl?(l,5-cyclooctadiene)]2 gave coordination polymers of the types [Pd(4,4*-diisocyanobiphenyl) ] (x=1.82±0.12) and [PdCl2(4,4'-diisocyanobiphenyl)]n, respectively. These matrices were characterized by means of elemental analyses, infrared, diffuse reflectance and X-ray photoelectron spectra as well as by thermal gravimetric and powder X-ray diffraction. The heterogeneous catalytic activity of these matrices was probed by monitoring the hydrogenation of several alkenes (e.g., 1-hexene, trans-2-hexene, cyclohexene, cyclooctene, 1,5-cyclooctadiene, 1-octene and styrene) and alkynes (e.g., J-hexyne, phenylacetylene, 2-octyne, methylphenylacetylene, and diphenylacetylene). The results of this study revealed some extraordinarily fast catalytic reactions taking place in the presence of the palladium(O) matrix under mild conditions. The catalytic hydrogenation of alkynes revealed selectivity with respect to the semi-hydrogenation process as well as stereoselectivity and stereospecificity with regard to cis hydrogenation. J - 80 - PALLADIUM CATALYSED ALLYLIC ALKYLATION WITH ALLENYL SFANNANE Ehud Keinan* and Moshe Peretz Department of Organic Chemistry, The Weizmann Institute of Science, Rehovot, Israel Allenyl trialkyl stannane was found to serve as an efficient nucleophile towards -n allyl palladium complexes (generated catalytically from allylic acetates and 5% Pd(PPho).). These allylic alkylations are taking place under mild neutral conditions and thus provide a novel chemoselective entry to 1,5-ene-yne systems: )Ac CN Pd(PPh3)4 The allenyl stanne nucleophile is a special case of e-y unsaturated organotin nucleophiles which react in a typical mode of allylic inversion: X = CH2, 0 UNDSEAS (ISRAEL) LTD. irua 38. King George St., Tel-Aviv T] ,38 'nvi i7nn aim P. O. B. 2 3 0 1 1 2 3011 .1 XI Phone: 299-091-2-3-4 Computer Aided Chemistry — the concept that is revolutionizing lab productivity PERKINELMER The microprocessor is at the first level of Computer Aided Chemistry This tiny chip now incorporated into almost every Perkm-Elmer instrument has re- sulted in a significant and dramatic increase in instru- ment productivity Improved control of instrument parameters automatic testing and calibration of instrument functions and ease of setup and opera- tion are |ust a few of the benefits of microprocessor- based instrumentation Model 3600 Data Stalon On the second level of Computer Aided Chemistry are the Perkm-Elmer Data Stations, with turnkey soft- ware for gas and liquid chromatography. for atomic, infrared, ultraviolet and fluorescence spectroscopy. and tor thermal ana elemental analysis Perkm-Elmer offers the broadest line of proven ready-to-use soft- ware in the analytical field interactive processing of instrument data is only one aspect of this phase of Computer Aided Chemistry Digital storage of instru- ment parameters and analytical methods, and auto- mation of repetitive procedures (from sampling to re- port generation) are a part of every Perkm-Elmer Data Station system Programmability in BASIC, and the ability to operate as an intelligent work station within a larger laboratory computing system, further contrib- ute to making the Perkm-Elmer Data Station the most Model983 dispersive IR with integral CRT and Model 1430IR Spectrophotometers powerful small computer for the analytical laboratory ICP/5500 — fastest, toughest, most flexible sequential ICP LANDSEAS (ISRAEL) LTD. 38. King George St., Tel-Aviv o rj js 'jmu -|?nn P.O.B. 2301 1 2 3011 .7 n Phone: 299-091-2-3-4 SERIES 4 LC with LC-85 Detector/Autocontrol and LC Terminal SERIES 4 LC: State-of-the-art versatility and performance By Roy W.Yost Other high-performance Perkin-Elmer pumping systems The SERIES 4 is a compact, high-performance qua- ternary solvent delivery system for HPLC, surprisingly SERIES 3B microprocessor-controlled LC. The moderately priced. A positive-volume proportioning SERIES 3B combines two performance-proven, dual- system delivers any combination of up to four sol- head 0-30 mL/min pumps with a maximum pressure vents into a unique ultra-low dead-volume, high- rating of 6000 psi (41.4 MPa) with a controller offering speed pump which operates at flow rates from 0.1 to five discrete full-curvature program segments, re- 9.9 mL/min. High flow rate precision and accuracy, verse gradient profiles and two-way RS-232C com- and instantaneous, in-pump solvent blending make puter communication capability. the SERIES 4 an ideal pumping system for both con- ventional and High-Speed/High-Resolution LC. SERIES 2/2. The SERIES 2/2 uses the same pumps All input to the microprocessor-controlled pumping as the SERIES 3B to provide mixed-solvent, linear unit is performed through a user-friendly keyboard gradient or dual independent use, in a lower-cost labelled in commonly-used chromatographic terms. module. The 2/2 is the ideal instrument for most The large video display unit shows a complete analyses not requiring the extra features of the method on a single screen page. During operation, SERIES 3B. the status of all key parameters is continuously dis- played and updated. SERIES 2/1. The SERIES 2/1 is a single-pump ver- The standard SERIES 4 system can store up to sion of the 2/2 which may be upgraded to dual-pump ten separate methods. The addition of the optional use as analytical requirements expand. Chromatographics 2 Data System provides the SERIES 4 with full data-processing capability along SERIES 1. The SERIES 1 is a single-pump system with disk storage of data and results. which is recommended for dedicated isocratic When methods are called into use — either man- analyses. ually or automatically sequenced — the SERIES 4 immediately selects the required solvents and proper flow conditions. If the optional ISS-100 Autosampler and full-contact column oven are installed, sample sequencing is also automated as is adjustment of column temperature. PHYSICAL CHEMISTRY - 81 - L ANATOMY OF COMPLEX REACTION SYSTEMS. KINETICS OF COMBUSTION REACTIONS FROM IGNITION DELAY TIMES Assa Lifshitz Department of Physical Chemistry, The Hebrew University, Jerusalem One of the very useful methods of solving the kinetics and mechanism of complex combustion systems is the measurement and modelling of the induction period which precedes the ignition of a fuel in a shock tube. When a mixture of a fuel and an oxidant is subjected to shock heating, it ignites, following an induction period known as the ignition delay time. This delay is the outcome of the exponential character of the overall reaction rate resulting from various chain branching reactions and adiabatic temperature rise during the course of the reaction. The delay time which is a readily measurable quantity is a function of the initial temperature, pressure and composition of the reaction mixture. The measurement of its dependence on the reactant concentrations and temperature provides a very powerful tool for modelling and thus understanding of the oxidation mechanism. It is useful to summarize the dependence of the induction time in a simple parametric relation that can later serve as a basis for computer modelling. The general relation between the induction time and the concentrations is very similar to the one which describes the rate of a reaction, that is, where T is the induction time, C is the concentration of reactant i, and B. is a parameter somewhat similar to an empirical reaction order. A can be presented as A = 10aexp(E/RT) an expression very similar to a reciprocal rate constant. The parameters a, E, and the g. are experimentally determined quantities, and they represent a mean to summarize the experimental results in a quantitative manner. After establishing an empirical relation as above and determining the parameters, one can perform computer experiments under conditions similar to the laboratory experiments and try for a given reaction scheme to reproduce its parameters. One then arbitrarily varies the magnitude of the various rate constants and examines their influence on the induction period. The role the particular reaction in the overall mechanism can be elucidated. Several examples are discussed. - 82 - QUASICLASSICAL TRAJECTORY STUDIES OF THE DYNAMICS OF THERMONEUTRAL ATOM-MOLECULE REACTIONS. Avigdor Persky, Michael Broida and Rachamim Rubin, Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel Quasiclassical trajectory studies of the dynamics of several nearly thermo- neutral atom-molecule reactions were carried out using semiempirical LEPS potential energy surfaces. The following reactions and their isotopic analogs were investi- gated: Cl+H2(v) »-HCl+H O+H2(v) • OH-ffl O+HCl(v) • 0H4C1 Cl+OH(v) • HC1+0. From the trajectories, cross-sections, rate constants, kinetic isotope effects and the energy distribution among reaction products were calculated and compared with experimental results. The effects of the vibrational excitation of the reactants and of the location of the potential energy barrier on the dynamics of the reac- tions were also investigated. - 83 - PICOSECOND KINETICS BY INFRARED LINE BROADENING Shmuel Weiss Department of Chemistry, Ben Gurion University of the Negev, Beer Sheva An exchange reaction in which a molecule alternates between two chemical envi- ronments causes vibrational lines to broaden, coalesce and finally narrow as the rate of exchange increases. The phenomenon, observable in the infrared (and Raman) is completely analogous to that in NMR and ESR but is on the picosecond time scale. Categories of reactions to which such line broadening may be applied as a means for studying their kinetics include: charge transfer complexes formation and dissocia- tion, hydrogen bond formation and dissociation, conformational transitions, proton transfer, ionization and reassociation. Experimental results on a number of these will be presented. - 84 - SOME APPLICATIONS OF A NEW MOIRE TECHNIQUE IN CHEMISTRY 0. Kafri Nuclear Research Center-Negev POB 9001 84190 Beer-Sheva Israel Recently we have developed a novel optical method based on moire effect. This technique, moire deflectometry^ ', is capable of measuring quantities usually measured by interferometry, namely, refractive index and/or geometrical changes. The accuracy of the method may reach that of interferometry. The method is very simple and noncoherent, thus the requirement for mechanical stability is imposed by the desired sensitivity of the measurement rather than by the wavelength of the radiation, as in interferometry. We applied this techniques to -some kinetic measurements. For example we have studied the kinetics of the evaporation of cooling liquid in the atmosphere. We saw that in water at temperatures above 50 C the evaporation rate is linearly proportional to the vapor pressure. Thus, one is able to evaluate AH evaporation in a very simple manner, from clausius - Clapeyron equation. At lower temperatures the process rate does not obey the C.C. eq. and is slower due to the non negligible humidity of atmosphere. In addition we'will describe- measurements of refraction index as a function of time and temperature measurements of flames by moire deflectometry. References 1. 0. Kafri, Optics Letters £, 555 (1980). 2. 0. Kafri and A. Livnat Appl. Optics'20, 3098 (1981) 3. I. Glatt, A. Livnat and 0. Kafri - to be published. - 85 - NOVEL ASPECTS OF ELECTRONIC ENERGY TRANSFER IN SOLUTION Shammai Speiser Department of Chemistry, Technion - Israel Institute of Technology, Haifa 32000 Energy transfer processes play a major role in determining the dynamics of excited molecular systems. Our present understanding of these processes enables us to elucidate mechanisms of photochemical reactions and photophysical properties of complex molecular systems. In the gas phase vibration to vibration, vibration to rotation and vibration to translation energy transfer processes are of major importance. In addition, electronic to vibrational energy transfer, and electronic to electronic excitation energy transfer are observed. Usually, energy transfer in the gas phase is studied under collisionally dominated conditions. By contrast, in condensed media and especially in fluid and solid solutions intramolecular vibrational and rotational relaxation processes are extremely fast and therefore only electronic energy transfer processes can be studied in these media; in many cases long range collisionless interactions promote these transfer processes. In this lecture, while covering the major aspects of the theory of energy transfer in solution, we will emphasize some recent developments in this field: Temperature dependent energy transfer, intensity induced transfer, involvement of high lying electronic states in energy transfer, determination of molecular structure and conformational change in macro-molecules resulting from intramolecular energy transfer, and utilization of energy transfer in dye laser operation. - 86 - 0 A Semi classical Adiabatic Theory of Resonances in 3D Reactive Scattering by Eli Pollak, Chemical Physics Department, Weizmann Institute of Science, Rehovot, Israel 76100, and Robert E. Wyatt, Institute for Theoretical Chemistry and Department of Chemistry, University of Texas, Houston, Texas 78712 Recently it has been shown that resonance energies in col linear reactive scattering can be predicted accurately by a semi classical quantization of resonant periodic orbits. The 3D analog of the orbit is In principle a quasiperiodic rotating, bending vibrating trajectory with quantised action along each degree of freeom. Since the time scales of rotation bending and vibration are usually well separated one can approximate this quasi-periodic orbit via an adiabatic reduction scheme. For fixed angles one first solves the fast vibrational motion. For each fixed angle one finds a resonant periodic orbit. This orbit then provides an effective potential for the rotation-bend Hamiltonian. One then solves for the bending motion to obtain an effective Hamiltonian for the 'sleepy' rotation. In this manner one finds that the 3D analog of the resonant orbit is a resonating, bending, rotating 'rod1. Numerical comparison of the semiclassical resonance energies found using this scheme with exact (H+h^) and J2 conserving (F+H2) quantal results shows good agreement. References 1. E. Pollak and M.S. Child, Chem.Phys. 60, 23 (1981). - 87 - 0 KINETIC ENERGY RELEASE DISTRIBUTIONS + (KERDs) FOR GAS PHASE IONS; C4HgO by C. Lifshitz and P. Berger Department of Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel As part of an ongoing effort, we are studying highly excited polyatomic cations and searching for the limits of statistical behaviour. The ions chosen for this purpose are enol cations which undergo a rate-determining isomerization followed by a fast bond cleavage.. This study is concentrating on the reactions + + C.H_O* -»• CoH_0 + CoH_. and C.Ho0* -> C_HcO + CH_ of the enol ions of 2-butanoUe. KERDs have been determined on a reverse geometry double focusing mass spectrometer by computer control and accumulation of the data. The potential energy profiles have been determined from appearance energy CAE) measurements. Bimodal distributions will be discussed in the light of possible deviations from statistical behaviour. Contributions from different product ion structure channels will be assessed. 0 GRAFTED MICROPOROUS REVERSE OSMOSIS (RO) MEMBRANES Moshe G. Katz, Soreq Nuclear Research Centre, Israel Theodore Wydeven, Jr., NASA - Ames Research Center, California. Asymmetric cellulose acetate membranes were chosen as model microporous membranes for the study of the effect of controlled modification of the membrane surface by graft copolymerization techniques, on their selective material transport properties. The study is guided by a similar approach to that proposed by Schultz and Asunmaa^ . In the present approach, possible changes in the effective viscosity of the "ordered" water, as a result of changes in the chemical structure of the membrane material are taken into account. The objectives of this study include investigation of the effect of the organizing inter- actions between the membrane surface and the adjacent water molecules on the state and properties of the "pore water". The grafting process was carried out in a glow discharge plasma. Preliminary results, obtained in the framework of grafting experiments in N«, ^o^4 anc* ^4 P^asmas will be presented REFERENCE: 1. R. D. Schultz and S. K. Asunmaa, Recent Progr. Surface Sci. 3, 291 (1970) - 89 - 0 FORMATION OF SPATIAL DISSIPATIVE STRUCTURES IN A PHOTOCHEMICAL SYSTEM M. Kagan, A. Levi and D. Avnir, Department of Organic Chemistry, The Hebrew University of Jerusalem Jerusalem 91904, Israel The possibility for the spatial formation of dissipative structures in a chemical system has long been predicted by Prigogine . Temporal and spatio- temporal dissipative structures are well known and have been studied intensively e.g. the Belousov-Zhabotinskii oscillating reaction2, and Winfree's waves.3 however until recently no chemical reaction system was known to produce purely spatial structures. Following a brief report of an observation by Mockel^ we have studied the effects of UV photolysis on a shallow layer of solutions con- taining a halogen radical source and a substrate which reacts with the halogen radicals, or with molecular halogen, to yield a coloured product. We have observed that, very shortly after the coloured product is first formed there is a breaking of the homogeneity of the solution into spectacular three dimensional shapes. These shapes are maintained and grow as long as the solution is contin- uously irradiated; if the light source is removed they diffuse back into homogeneity. The role of the light, therefore is not only in the formation of the halogen radical source but also to drive the reaction far enough from equilibrium to allow for multi-stabilities. In identifying the necessary feed-back loop we have verified the prediction of Ross and Nitzan^, and completed the triad of chemical dissipative structures. We have found over 5Q reaction mixtures that show this effect and are presently investigating the generality of the phenomenon. Some examples are: KI/starch/ water; tryptophan/chloralhydrate/water; 4-iodo-aniline/cyclohexane. Finally, we draw attention to the significance of our study in the framework of chemical models to prebiotic evolutionary processes. The spontaneous gathering of molecules out of a homogeneous environment, must have been the earliest stage in the evolutionary time hierarchy. The phenomenon we describe is a model system for such processes, the first one for a diffusion/chemical reaction network. 1. I. Prigogine and E. Nicolis, J. Chenu Phys. 46_, 3542 (1967]. 2. A.M. Zhabotinskii, Bioligika 9_, 306 (1964). 3. A.T. Winfree, Sci. Amer. 82, June (1974). 4. P. Mockel, Naturwiss., 64_, 224 (1D77). 5. J. Ross, A. Nitzan and P. Ortoleva, J. Chem. Phys. 60_, 3134 (1974). - 90 - 0 THE MINIMAL CHEMICAL OSCILLATOR K. Bar-Eli Department of Chemistry, Tel-Aviv University, 69978 Tel Aviv, Israel and W. Geiseler Technical University of Berlin, Berlin, West Germany. Abstract An open flow cerium-bromate-bromide system is investigated. The system shows bistability under some constraints and monostability under others. The mathematical properties of the system were investigated. It was found that near the critical point, where the bistability disappears, the system starts to oscillate since only one unstable steady state exists in that region. The predictions regarding the range of bistability and the existence of oscil- lations were borne out by experiment. The system turns out to be the simplest known chemical oscillator. - 91 - 0 PERTURBATIONS OF BISTABLE CHEMICAL SYSTEM K. Bar-Eli Department of Chemistry, Tel-Aviv University, 69978 Tel Aviv, Israel W. Geiseler Technical University of Berlin, Berlin, West Germany. Abstract A bistable chemical system may be subjected to small perturbations, which leave the system in its previous steady state and large ones, which cause transitions from one state to the other. The small perturbations were investi- gated for the possibility of using them as a tool to measure a particular rate constant. Large perturbations were shown to cause transitions only if they last long enough. Relationships between the perturbation intensity and length are found. They seem to be of a similar nature as those developed by neuro- physiologists in order to explain excitation of nerves by electrical pulses. References 1. H.A. Blair, J. Gen. Physio!. T5_, 709 (1932) ORDER AND DISORDER IN NONAQUEOUS SOLUTIONS OF ELECTROLYTES N. Lotan Biomedical and Chemical Engineering Departments, Technion, Haifa, Israel We have previously reportedf'] on the conformational states of polymers in electrolyte - containing nonaqueous solutions. Thus, using a variety of physico-chemical techniques, polymers bearing amide, ester, and phenolic moieties have been investigated. We have concluded that, under appropriate conditions, high charge density ions - such as Li+- bind to the macromolecules and, as a result of it, pseudopolyelectrolytes are formed. These effects are cancelled when water is added to the system. It was suggested that these phenomena are promoted by specific interactions occurring between the electro- lyte and the solvent. The present report describes the testing and the confirmation of this hypothesis. Concentrated solutions (4-6 M) of LiCl in methanol exhibit rather unusual properties: they are not miscible with ether f their viscosity is very high (up to 20 times the viscosity of methanol), and their nH nuclear magnetic resonance spectrum exhibits a quartet and a doublet for the -OH and the -CH3 groups respectively. When water (5-20%) is added to this solution, a separate singlet peak - assigned to the slowly exchanging HOD - is observe-i in the spectrum. At higher water content (50%), the -OH peaks of water and methanol coalesce into a singlet, and the same is the case for the - CHo doublet peak. Related results were obtained for trifluorcethanol - containing solutions, with the difference that, in these cases, lower concentrations of LiCl (0.1 - 0.2 M) are required. The effects described are interpreted to indicate that the Cl~ anion is strongly solvated by methanol,and even more so by trifluoroethanol. Extensively structured liquids are thus formed . As a result of it, "naked" Li+ cations of high thermodynamic activity are obtained. This view is supported by the results of electrolyte conductance measurements[2]on these solutions. References 1. N. Lotan, J. Phys. Chem., 77, 242 (1973). 2. D.F. Evans, J.A. Nadas and M.A. Matesich, J. Phys. Chem., 75, 1708 (1971). - 93 - 0 FRACTAL SURFACES: CHEMISTRY IN AN ENVIRONMENT OF A NON-INTEGER DIMENSION GREATER THAN TWO P. Pfeifer(a'15, D. Farin(b) and D. Avnir(b) fai " F. Haber Research Center for Molecular Dynamics'- ' and the Department of Organic Chemistry^ , The Hebrew University of Jerusalem, Jerusalem 91904 Israel. Chemistry has been treated traditionally in a three-dimensional (bulk) or in an ideal two-dimensional (surface) environment. We suggest that in many cases a more natural way to analyse physical behaviour, is to do so in a dimensional environment which has a non-integer value between 2 and 3. More specifically, the main point is that irregular surfaces have an effective dimension greater than two. This effective dimension, termed "fractal dimension", D, (after Mendelbrot(2)) is an intensive characterization, which gives a quantitative measure with predictive power for a property which so far has been treated with great difficulty: the irregularity of surfaces. This problem is encountered in diverse fields such as surface chemistry, crystal growth> catalysis, host-guest interactions in proteins, enhanced Raman and fluorescence effects. We have developed three independent experimental methods for determination of D: by analysis of the dependence of surface area on the cross sectional area of different molecules used for monolayer coverages(3*4)j by analysis of the dependence of the surface area measured with a fixed yardstick-molecule, as a function of particle size^/j and, if irregularity is due to porosity only, by analysis of pore-size distribution curves. * Existence of a well defined value of D requires the surface to be self-similar upon magnifi- cations. Remarkably, we find that this seemingly strict condition is obeyed very ,,.. often for a wide variety pf adsorbents, i.e., fractal nature of surfaces is abundant. We have studied so far^ * ' silica gels, charcoals, graphites, clays, crushed glass, and found D values of the whole range. Thus, for graphite we obtain D=2.0 and for a charcoal D=2.7. (1) Current address: Fakultat fur Chemie, Universitat Bielfeld, D-4800, Bielefeld, FRG. (2) B. Mandelbrot, "Fractals", Freeman, San Francisco, 1977. (3) D. Avnir and P. Pfeifer, preprint, 1982. (4) P. Pfeifer and D. Avnir, preprint, 1982. (5) D. Farin, D. Avnir and P. Pfeifer, preprint, 1982. 0 NON-EQUILIBRIUM CHEMISORPTION IN HETEROGENEOUS SYSTEMS H. Birnholtz, Ch. Aharoni, A. Nir, and N. Lotan Department of Chemical Engineering, Technion, Haifa, Israel. Chemisorption of materials from the gas phase onto the surface of a solid adsorbent is affected by temperature and pressure. Thus, for example, the exothermic character of the process predicts that equilibrium isobars will be monotonously descending functions of temperature. Such an appearance was in- deed observed experimentally in a variety of systems, and a schematic represen- tation of it is shown in Fig.l (curve A). In some instances, however, one notes a rather peculiar behaviour, namely isobars show a minimum, a maximum,or both (Fig.l, curve B). Amount of material adsorbed Figure 1.Schematic repre- sentation of chemisorption isobars. Temperature In the course of our studies on chemisorption we have developed a model which takes into consideration both the equilibrium states and the dynamic aspects of the process, while assuming that: a) the adsorbing surface is heterogeneous and made up of two types of sites; b) material from the gas phase can reach the surface only at sites of one type, while the other sites are supplied merely from the former ones, and by a surface diffusion process. This model accurately predicts the complex type isobars mentioned above (Fig.l, curve B), and reveals the fact that they actually represent transient states rather than equilibrium ones. The latter (Fig.l, curve A) are reached after extended periods of time, and are also accounted for by our model. - 95 - Magnetic Circular Dichroism studies of DAB CD Aharon Gedanken Department of Chemistry, Bar-Ilan University, Famat-Gan 52100, Israel Absorption and multiphoton ionization measurements of DABCO (1,4 diazabicyclo [2 ,2,2]octane) were able to identify two electronic transitions. The origin of the first one is observed at 279.37 nm and is assigned as the n •*• 3s Rydberg transition while the second transi- tion is located at 251.1 nm and is assigned as the n •*• 3p transition. Differences exist in the assignment of n -»• 3p transition. Halpern et al. 2 11 and Hamada et al. prefer the A' •* A" (n -»• 3p2) transition, while Parker and Avouris concluded that it should be assigned as the \ -%• {„ - 39^). We have carried out MCD measurements of DABOO in the gas phase and obtain for each member of the vibration.il progression of the n -*• 3p a derivative line-shape A term. This observation immediately requires the conclusion that the excited state involved in this transition is degenerate. The transition is therefore unambiguously assigned as A' -*• E1 (n -> 3p ). 1 1 xv The magnetic moment of the excited E1 was calculated to be -0.173+0.02 where 3 is the Bohr magneton. References 1. A.M. Halpern, J.L. Poebler and K. Weiss, J. Chem. Phys. 49_, 1348 (1968) 2. Y. Hamada, A.Y. Hirakawa and M. Isuboi, J. Mol. Spect. jl7_, 440 (1973) 3. D.H. Parker and Ph. Avouris, J. Chem. Phys. 2i» 1241 (1979) - 96 - 0 MOLECULAR DYNAMICS OF POLYMERS IN CHAOTROPIC MEDIA N. Lotan Biomedical and Chemical Engineering Departments, Technion, Haifa, Israel The chain conformation and intramolecular mobility of nonionizable poly- amides, in water and in calcium chloride-containing aqueous solutions, have been studied. The polymers considered were of two classes: chiral (polyamino acids) and achiral (poly-N-vinylpyrrolidone), and their hydrodynamic and nuclear magnetic resonance (NMR) properties were investigated. The conformation and conformatio- nal transitions of polyamino acids were also established by circular dichroism measurements. For comparison, corresponding NMR properties of low molecular weight model compounds were also determined. A typical effect observed in our polymer-containing systems is presentod in Fig.l. The main feature revealed is the extreme broadening of the NMR peaks HOD Figure 1. NMR spectra of poly-N-vinylpyrrolidone: (A) - in DO (B) - in 3.9 M CaCl in D 0 occurring upon increasing the salt concentration. No such feature was noted with low molecular weight model compounds. The ensemble of the results obtained are interpreted to indicate that, in water, the polymers assume a disordered and flexible conformation, of high mobility. Upon increasing the salt concentration the overall disordered confor- mation of the polymer chains is preserved, yet the intramolecular mobility and chain flexibility are progressively lost. It is hereby suggested that these effects are caused by a multidentate binding of Ca ions at the amide groups, leading to intramolecular bridging of the polymer chains. - 97 - ''Local Field Enhancement in Aggregated Dielectric Films" Zvi Kotler and Abraham Nitzan Department of Chemistry, Tel-Aviv University Tel Aviv 69978, Israel Results of calculations aimed at estimating enhancement ratios for averaged electromagnetic field intensities in island films are presented. The enhancement ratio for the inter^island environment is calculated using Nitzan-Bergman enhance- 2 ment ratio for two component materials - and is found to be of the order of MO for Ag particles. The film is modeled by a distribution of ellipsoids of revolution lytng on a substrate with their optic axis perpendicular to it. The dipole approximation is employed and care is being taken of image effects, size effects and radiation damping. The magnitude of the enhancement and peaks position are found to be dependent on the particles' shape, size and density, and also on the substrate chosen. - 98 - TIME RESOLVED PHOTOIONIZATION MASS SPECTROMETRY by C. Lifshitz, M. Goldenberg and Y. Malinovich Department of Physical Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel A photoionization mass spectrometer operating in a time resolved manner, from the microsecond to the millisecond range, has been constructed. The central part of the instrument is a Cylindrical Ion Trap (C1T) of the type used previously in conjunction with electron impact experiments. A Hinteregger VUV light source is operated in a pulsed mode and the photoions produced are trapped in the CIT. They are ejected into a quadrupole mass filter by a drawout pulse, following a variable delay time, and counted only during the ejection pulse. The instrument is being employed for measurements, of time resolved photo- ionization efficiency curves and breakdown graphs. Reactions studied include CgHg -*• CM, + C2H_ in cyclo-octatetraene, which demonstrates a very slowly rising rate-energy dependence as function of the excess energy above threshold. It is estimated that dissociations, having rate coefficients kCE) « 1 sec~ , can be detected. - 99 - FLUORESCENCE STUDIES OF RUTHENIUM TRIS-BIPYRIDINE AND OF EUROPIUM TRIS- BENZOYLACETONATE ADSORBED ON POROUS SUPPORTS* N. Manor(aj, R. Reisfeld^** and D. Avnir^ The Departments of Inorganic and Analytical Chemistry^(a) J and Organic Chemistry^" , The Hebrew University of Jerusalem, Jerusalem 91904, Israel. As part of our study of surface effects on photophysics and photochemistry of adsorbed molecules we have investigated the fluorescence of ruthenium tris- bipyridine (RTBD) and of europium tris-benzoylacetonate (ETBA). Two types of transparent surface-hydroxylated porous adsorbents were used: (a) Compressed discs of fumed silica-gel. These were obtained by applying a pressure of ^10 tons/cm^ on the 14 ym particles of the silica; (b) Corning Vycor porous glass 2 (7930), of surface area 200 m /gr (by the N2 BET method). The pore diameter range, 40-7Q&, is sufficiently large for the penetration of the organometallic dyes. We have found that high luminosities are obtained from the adsorbent plates. E.g., for ETBA we have found a remarkable enhancement in luminosity as compared to solution. Longer fluorescence life times were observed for both adsorbed RTBD and adsorbed ETBA as compared to solution. These phenomena probably result from: a) the ability to achieve high concentrations due to the large surface area.of the adsorbents; b) strong adsorbent-adsorbate interactions which diminish adsorbate intermolecular quenching processes; and c) in the absence of solvents, fluorescence quenching by high stretching frequencies is avoided. We draw special attention to the significance of our findings, especially with RTBD, in the context of luminescent solar collectors. This aspect of our work is discussed elsewhere. In a typical experiment, a 1.3 mm thick 0*00 mg) Vycor plate was loaded with RTBD to a concentration of 4*10~2 moles of dye per liter of glass. Life time measurements (emission: 620 ran) on the strongly luminescent plate revealed an exponential decay rate with a mean life time of 0.45 ysec (0,37 ysec in solution). In contradistinction to RTBD, the decay rate of ETBA is non-exponential. This difference is attributed to island formation of ETBA upon adsorption, whereas RTBD probably forms an evenly spread layer. Further experiments are in progress. * Partially supported by the Israel Ministry of Energy and U.S. DOE contract No. 80-1-09, and by the E.D. Bergmann Foundation. ** Enrique Berman Professor of Solar Energy. - 100 - (BSA) innni *ro 'ny *tv nm ntna n*ai .jmayn Din D11D2 mna ,'3 ax . nms nain Nin np'ui'p Vy yi'nn TXIJ 'HB»NT Dp"73mp ~>D liHuni .stopped flow Team nx m^n m 'inN ;Tnn 1 23 s" *7B> ni'iun QN paiv'zn n'Vnm ,'7n"7 pm xm 'JIWKIH op^smpn 'D in nnpiyn ni'ymiDonun -»ne» 'D niNxinn hv nT'*73Nn nxm p-ino 'yiap T\H 'U3'p IQIKI ^IP1? IK/DN-'N ,13*7 .ninny HTXP^'T *7» imyn nunni .nn'nnn 'yiap A VD IIN D'V'^nn O"ion DHB .n'XDp^in 'am HN PTI IN N*7N inn 'D aisvn1? in'i n'n »pH n n'^y oy m^iy ni'ii'nnn VDW uran naiiv N'n HT nayn VB* imn IN .Tma^Na 7.5 pH na'a^i "7nn T^nn ,N ^ B aiw laiiNxn "pH nx'Dp" mji'pja ,ITMO .pH a ni»n»nnn niVn "7B» un 'mno '3 11*7 nNia ID1? .Dp^ampn nvy*1? a'on'unn nVNn mi' D'T»no IH .n'^Dp^T 'am nayn1? •JIDP'TJ'N N^N minn ia-»N pan'^'ani ,N t B laynn IIN D'rnn nVn D'3iiT .•»ynian-Tn i9iKa un nnann m n^in1? in'! own nVNi?1; Tm'na Tiam JJN - 101 - PICOSECOND TIME RESOLVED ELECTRONIC ENERGY TRANSFER IN MIXED CRYSTALS AND FLUID SOLUTIONS D. Rojansky and D. Huppert Chemistry Department, Tel-Aviv University, 69978 Ramat-Aviv, Israel Picosecond time resolved fluorescence spectroscopy measurements were used to investigate electronic energy transfer (EET) in the following systems: 1) tetracene doped anthracene crystals 2) anthracene and tetracene doped naphthalene crystals 3) methanolic solutions of rhodamine 6G(R6G),and fluorescine disodium salt 4) methanolic solutions of fluorescine disodium salt and DODCI. In the fluid solutions the donor (Fluor. Dis. salt) concentration is in excess with respect to the acceptor concentration (DODCI, R6G). It was found that the host luminescence decay law: 3 2 3/4 n(t) = n°(t)exp(- | ^2_ Cft /IT- o^Sx*^ ' (Dto) ^ ) fits well with the experimental data. This expression was proposed by Gosele and Golubov and Konobeev for combined exciton diffusion and long- range transfer. (Postdeadline) - 101a - P RESONANCE RAMAN SCATTERING AND FLUORESCENCE OF MOLECULES ADSORBED ON SILVER-ISLAND FILMS D.A. Weitza, S. Garoff3, J.I. Gersteinb and A. Nitzanc a Exxon Research and Engineering Co., P.O. Box 45, Linden, NJ 07036 b Department of Physics, City College of the City University of New York, New York, NY 10031 c Department of Chemistry, Tel-Aviv University 69978 Ramat Aviv, Israel and Department of Chemistry, Northwestern University, Evanston, IL 60201 The enhancement of regular raman scattering (RS), resonance raman scattering (RRS) and fluorescence from molecules adsorbed on identical well characterized Silver-Island films are reported. A hierarchy of enhancement ratios is found with typical values of 10 for RS, lo3 for RRs and 0.1-3 for fluorescence, the latter depe-nding on the quantum yield associated with the fluorescence of the free molecule. These experimental results are discusssed within theframework of the electromagnetic theory of SE?S generalized to treat molecular resonance phenomena. The relative intensities associated with the observed RS, RRS and fluorescence processes lead to a determination of the role played by the surface plasmon resonances and by the surface induced damping of the molecular excitation, in these various types of light scattering processes. The observed hierarchy of enhancements is shown to have important spectroscopic consequences. A new age in liquid scintillation measurement systems The TRI-CARB460C by Packard Packard The World Leader In Liquid Scintillation Counting Linear Recorders High quality and reliable performance are critical to most applications. That is why Linear recorders have been selected by more than 43.000 laboratories, universities, research centers, medical institutions and private indus- tries throughout the world. Linear has been an innovative leader in analog strip chart recorders since 1971. Our pen Jrive system was patented in 1978. 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This feature allows not only ease meter which enables the operator visual communication for all the of operation for inexperienced operators but also more sophisticated conditions and the results of measurement for both of spectrum and work for the experienced operators. continuous gas measurement by Infrared mf'ced onc.vze'S fc *he r^eosurerrer-T cj * 'J 00:65 ~he^e solid ^o*e oerector cnoiyzers ;ffer fcs' -esporse .C\A roc-e. high occuccv ,ow rncptencrce oro o modercTe price \r< Mode: ?C; --iPQie go:, onoiyzer IP Mode. 7C2 orcyze; two gcses s IP Modei /DC mu't: pet sonnpie gos conditone' INFRARED INDUSTRIES, INC. Western Division, Instrumentation Group P O Box 989. Santa Barbara, CA 93102 (805)684-4181 Represented by ELOAIM ELECTRONIC INSTRUMENT CO. LTD. \ Eldan 16 OHOUAV STREET • JERUSALEM 94467 SBAEt. P.OB. 137O. JERUSALEM 91O1S TEA Analyzer For Nitrosamine Analysis 0 0 sfc Thermo llz Electron COSPOfliTION Analytical Instruments Represented by ECDAIM ELECTRONIC INSTRUMENT CO. LTD. I Eldan 16 OHOLIAV STREET • JERUSALEM 94467 P.OB. 127O. JERUSALEM 91O1S ELECTROCHEMISTRY - 102 - PHOTOELECTROCHEMICAL SOLAR CELLS David Cahen, the Weizmann Institute of Science, Rehovot The photovoltaic effect at the semiconductor/liquid electrolyte junction can be used to construct a photoelectrochemical cell (PEC). Such a cell has several attractive features, such as the possibility of using thin film polycrystalline semiconductors with minimal conversion losses. Work at the Weizmann Institute has been concerned with producing such cells with acceptable output stabilities and performances, and thus with identifying factors that affect these characteris- tics. Several systems are under investigation, and of these the Cd-chalcogenide (CdSe, CdTe)/polysulfide is the most advanced. Solid state chemical considerations led to our study of ternary chalcogenide/polysulfide PEC's. These latter systems show superior output stability and, when single crystal semiconductors are used, performances comparable to those of the former ones. For all systems proper surface treatments are necessary to achieve optimization. This leads to another aspect of this kind of work, viz, reaching an understanding of the semiconductor surface chemistry, using electrochemical methodologies. Achievement of this goal clearly has a bearing not only on solar cells, but on many other areas of semi- conductor technology. - 103 - DOUBLE LAYER EFFECTS IN SQUARE WAVE POLAROGRAPHY Ch. Yarnitzky Department of Chemistry Technion - Israel Institute of Technology, Haifa, Israel Square wave polarography is useful in basic electrochemical research and trace analysis. In either case, the charging current must be taken into account when the polarograms are evaluated. It is well known that as the potential changes the fast charging current decreases rapidly, (assuming that the double layer-cell resistance time constant is much shorter than the square wave period) to the small charging current accompanying the growth of the mercury drop. However, the periodic change of the potential causes some change in the surface tension of the drop, which depends on the direct potential and the amplitude of the square wave. Mechanical vibrations of the drop, occurring at a certain drop mass, generate another type of charging current which appears as a current peak. This peak must be identified and distinguished from the peaks recorded when electroactive species are present. In addition, the small charging current distorts the base-line and limits the sensitivity of the method. Background compensation has been achieved by adopting the alternate drop method or a computerized system. The first method doubles the electronic noise and recording time, and the second is too complicated for use in conjunction with laboratory instruments. We have proposed integrating the fast changing current and using this charge as a source for the compensating current. The mathematical relations between the vibrations and the drop parameters, as well as the theoretical treatment of the new compensating technique will be discussed. - 104 - DELAYED OPEN-CIRCUIT VOLTAMMETRY Dov Talmor and Emilia Kirowa-Eisner Institute of Chemistry, Tel-Aviv University, Tel Aviv G997ti A new technique, DELAYED OPEN-CIRCUIT VOLTAMMET.RY (DOV) is proposed for the quantitative treatment of chemical reactions e _ kf following charge transfer*. 0 ku The technique is related to a previous one used by us, i.e., the REVERSE PULSE POLAROGRAPHY method (RPP). The principle of DOV is as follows: The electrode is potent iosta ted for a time tg at a potential at which tiie electroactive material, 0; initially present in the solution is reduced at the diffusion limited rate. Products (P) and intermediates (I) are accumulated in the diffusion layer. The electrode is then disconnected and left under open circuit conditions for a time t While at open circuit, the chemical reaction in the diffusion layer proceeds simultaneously with diffusion of all the species. The progress of the chemical reaction is then followed by applying a potential pulse in a region in which the intermediates and the products are oxidised. The pulse potential is changed and the sequence is repeated changing the potential of the pulbe. In the case in which I and P exhibit separate oxidation waves, the obtained DOV contains direct information on the relative concentration of the species present in the immediate vicinity of the electrode as a function of time. Working curves for the determination of the rate constants are calculated by digital simulation, taster reactions can be studied with DOV compared to RPP. - 105 - 0 ELECTRO-CATALYTIC REDUCTION OF O2 BY METALLO-PORPHYRIN MONOMERS AND DIMERS J.Y. Becker, D. Dolphin, J.B. Paine III and S.F.B. Pickett Departments of Chemistry, University of British Columbia, Vancouver, B.C., Canada, and Ben-Gurion University, Beer Sheva, Israel. The electrolysis of 02 reduction has been studied using the rotating ring-disk method- A pyrolytic graphite disc was coated with varying amounts of cobalt(II) octaethyl- porphyrin, cobalt(II) mesoporphyrin II dimethyl ester and polymethylene-bridged doubly-linked cofacial dicobalt porphyrin dimers. Electrocatalytic reduction of O_-saturated 0.5M aqueous trifluoroacetic acid showed that at high adsorbed concen- trations monomeric porphyrins may be efficient catalysts for electroreduction of 0 to H20 although some H2O2 is detected at the Pt ring electrode. - 106 - 0 LOW-RATE Li/S ORGANIC CELL H. Yamin and E. Peled Department of Chemistry, Tel-Aviv University, Ramat Aviv, 69978 Tel Aviv, Israel The Li/S couple has one of the highest theoretical gravimetric and volumetric energy densities. This paper describes the development and electrochemistry of low-rate laboratory Prototype button cell. As a test vehicle for the research, we used a laboratory pro- totype stainless steel button cell. The cathodic-current collector was teflon bond- ed carbon electrode supported on Ni Exmet. It was charged by elemental sulfur or polysulfide. Celegard porous polypropylene, or glass paper, were used as separators. Sealing of cover to can was accomplished with the use of a combination of organic elastomer and cement (to avoid crimping). This sealing was leak proof since cells which were stored for three weeks at 60°C lost less than 1 mg of weight. Two types of cells were built: Type A - 900 wh/1 (or 1130 wh/kg) cell. All en- ergy density values were calculated on the basis of all cell components, excluding the case. Electrode area was 2.5 cm2 and cell's internal thickness was 2.1 mm for type A and 2.5 mm for type B. Net volume of cells was 0.6 and 0.72 ml for type A and B, respectively. A very important feature of Li cells is the low self-discharge. Several differ- ent self-discharge and Li corrosion tests have been made. Some of them are present- ed here. Capacity loss at 60°C, both under OCV or during discharge, was found to be 2-5% per month depending on the electrolyte composition. From these and other tests it is estimated that the shelf life of Li/S cells at room tesuperature will be ten years or more. Sulfur utilization in type A cells, at room temperature, exceeds 95%, and the cell's energy density is 900 wh/1 (or 730 wh/kg). Type B cells at 60°C delivered 86% of its nominal capacity, i.e. 950 wh/kg (or 1200 wh/1). Discharge curves are flat (above 2.0V). Cells were successfully discharged at -20 to +70°C. Nominal present rates for continuous discharge are: 5, 10-15 and 20-30 yA cm"2 for -20, 25 and 60°C respectively. Cells can deliver short current pulses up to 0.1 mA cm"2. - 107 - 0 The behavior of the Li/SOC^ system at elevated temperatures M. Babai, J.Bineth Lithium Battery Plant Tadiran, Israel Electronics Industries. Ltd. P.O.Box 75, Rehovot, Israel 76100 One of the promising ambient primary lithium systems selected for commercialization in recent years utilizes the lithium-thionyl chloride couple. This system is characterized by its high energy density (gravimetric and volumetric), good operating capabilities over a wide temperature range, reasonably high current delivering capabilities and low self-discharge rates. In this system, thionyl chloride serves the dual role of an electrolyte carrier for the solute ions as well as a cathodic depolarizer. Contrary to most other ambient lithium systems, where organic solvents serve as the electrolyte, the absence of organics in the Li/S0Cl2 system is reflected by an enhancement of both the chemical and the electrochemical stabilities of the Li/SoCl^ system. There is evident improved stability in storage and discharge capabilities at temperatures as high as 150^C, even though the boiling point of the thionyl chloride electrolyte is only about 0 This report summarizes the electrical performance of D-size cylindrical cells withnominal capacities of 10 AH at temperatures up to 150°C. It is shown that above 100°C, decomposition of thionyl chloride to chlorine, sulfur dioxide and sulfur monochloride takes place. The decomposition products increase the rate capability of the cells and change the morphology of the passivation layer on the lithium anode. The scanning electron microscope (SEM) photographs of the film grown on the anode, following storage for 7 days at temperatures up to 185^C, are given. The results confirm a duplex film mechanism, suggesting that the passivation layer on the lithium anode corsists of a thin, dense insulating LiCl layer underlaying a much thicker layer of porous, non-insulating LiCl film. The thin, dense film determines the distinctive electrochemical stability of the Li/SOCl2 system. - 108 - ENSEMBLE OF MICROKLLCTKODES: DIGITAL SIMULATION BY THE TWO- DIMENSIONAL EXPANDING GRID METHOD APPLIED TO CYCLIC VOLTAMMETRY Hannah Keller, Emilia Kirowa-Eisner and Eliezer Gileadi Institute of Chemistry, Tel-Aviv University, Tel-Aviv 69978 In an ensemble of microelectrodes, the surface is composed of active sites and inactive areas. Diffusion towards the active site has a radial component in addition to the perpendicular component, resulting in a thinner diffusion layer than calculated for semi- infinite linear diffusion. Hence, faster electrode reactions can be studied on ensembles of microelectrodes than on large electrodes (1). Linear potential sweep is widely used with stationary solid electrodes for the elucidation of the mechanism of electrode reactions. The use of ensemble of microelectrodes extends the ran-je of cyclic voltammetry to the study of faster electrode reactions. The mathematical treatement is based on the digital simulation method proposed by Feldberg (one-dimensional expanding grid) (2). for the case of microelectrodes, this method is further developed here for a two-dimensional expanding grid. Compared with a uniform grid, a considerable saving in computation-time is acheived. References 1. H. Heller, E. Kirowa-Eisner and E. Gileadi, J. Electroanal. Chem., in press. 2. S.W. Feldberg, J. Electroanal Chem. 127 (1981) 1. - 109 - Time Resolved Photocurrent Photopotential and Photoluminescence Study of n Type CdS and CdSe Photoelectrodes 2. Harziona, N. Croitoru , D. Hupperta and S. Gottesfelda a Department of Chemistry, University of Tel-Aviv, Israel Department of Electronics, University of Tel-Aviv, Israel The importance of kinetic parameters in the determination of the efficiency and stability of semiconductor photoelectrodes has been stressed by many authors. Transient techniques have served as an important tool for the evaluation of kinetic parameters in both electrochemical and solid state solar cells. The use of such techniques in photoelectrochemical cells has been introduced recently. Short light pulses aimed at the semiconductor surface are used in such techniques to perturb the photoelectro- chemical system. We have previously studied the photocurrent transients in a CdSe/S~, S° cell, generated by short (nS) light pulses (1). The detailed analysis of the photocurrent transients decay time (1) revealed that it was RC controlled, with the value of R reflecting the extent of trapping in the damaged surface layer. It was found that photocurrent decay is sensitive to the state of the photoelectrode (CdSe crystal) surface.: Chemical etching enhanced the amplitude and reduced the decay time of the transients, and increased the photocharge obtained (per flash). In subsequent measurements of electrical transient signals, the open circuit photo- potential transients revealed a decay rate which is proportional to the value of the dark current measured for the same semiconductor electrolyte interface under a small applied bias. This result ("RinfC controlled" decay) means that under open circuit s conditions Rjn^ * determined by the rate of the majority carriers transport across the barrier to the outer surface, where the recombination takes place. Analysis of the apparent R^nt.C time constants and their comparison to measured dark currents, reveals that the kinetics of charge separation ;cart be.followed. Incomplete charge- separation is.encountered in damaged surfaces. Finally, photoluminescence decay and quantum yield studies, following pS laser pulses, show a parallel bahaviour following the same surface treatments: The lumines- cense decay time for the etched crystals is 10 times longer than in mechanically polished crystals, and the quantum yields increase by more than an order of magnitude. Of special interest are results on sub-bandgap luminescence (SBGL) processes, which proceed at high quantum efficiencies in some of the samples examined. The SBGL processes reflect very fast recombination modes, and may also provide information on the involvement of mid-gap states in the photocharge transfer process. The combination of transient photocurrent, potential and luminescence measurements thus seems to be a promising approach to the identification and monitoring of the component processes of the photoelectrochemical reaction. Reference 1) Z. Harzion, N. Croitoru and S. Gottesfeld, J. Electrochem. Soc., 128, 551 (1981). - 110 - ELLIPSOhETRIC AND IMPEDANCE MEASUREMENTS OF OXIDE FILMS GROWN ON RUTHENIUM ELECTRODES J. Rishpon, I. Reshef & S. Gottesfeld Department of Chemistry Tel Aviv University The nature of the oxide layer formed electrocheaiically on Ru electrodes in acidic solutions and its electrocatalytic properties for the oxygen evolution reaction were investigated by combined ellipsometric/reflectometric measurements and by ac impedance measurments. An automatic ellipsometer employing a rotaintj analyzer and controlled by a microcomputer was developed. In this system the computer controls the rotating speed of the analyzer, collects the light-intensity data and calculates the optical properties of the electrode/solution interface. This ellipsometrie system was used to follow _in situ growth of the oxide films. Changes in the optical properties of the interface during constant anodic polarization or cyclic multipulsing indicate the formation of a spongy and hydrous RuOx layer. A limiting thickness of 300 A was observed for films grown by anodic polarization, while cyclic multipulsing results in a much thicker oxide layer (up to a few thousands A). Ac impedance measurements provided information about the internal mediating redox system in this oxide electrocatalyst film. The growth of the oxide in 0.5M sulfuric acid is associated with a gradual change in the shape of the complex plane plot, which at small film thicknesses indicates a distribution of response times due to nonuniformity of the active sites. For thick oxides the response function describes the charging of a uniform film with many identical active sites through a simple ohmic resistor. The effect of pH on the electrode response function suggests that proton mobility within the films has a strong effect on the surface electroact iv ity. - Ill - COOPERATIVE PHENOMENA IN THE ELECTROCHEMICAL BEHAVIOUR OF ANODES MODIFIED BY ANODIC DEPOSITION OF NICKEL COMPLEXES David A. Issahary and Dan Meyerstein Chemistry Departments, Ben Gurion University of the Negev and Nuclear Research Centre Negev, Beer-Sheva, Israel A deposit is formed by anodic treatment of Pt, Au or graphite electrodes in alkaline solutions containing complexes of nickel(II) with tetraazamacrocyclic ligands. The deposit thus formed is an electrocatalyst for the oxidation of water and alcohols. The electrochemical redox processes occurring in the deposit, which in the absence of alcohols are well separated from the catalytic process, were studied in detail. Effects of changing the deposit thickness, pH, voltage scan rate etc. are reported. A computer simulation of the oxidation of the deposit using a modified form of the Butler-Volmer equation indicates that the "pseudotransfer coefficient" for this process is large, cji 10 under some conditions, and depends on the nature of the anode, the complex used and the thickness of the deposit. Furthermore a correc- tion term indicating that interactions between the oxidized sites exist has to be introduced. The effect of the deposit on cyclic voltammograms of Fe(CN)4 - was studied. Analysis of the results suggests that the deposit consists of nickel complexes bound to each other via p-hydroxo or oxo bridges and that the deposit behaves as a semiconductor. - 112 - A SEMI-EMPIRICAL METHOD FOR RESOLVING OVERLAPPING WAVES IN CYCLIC VOLTAMMETRY Gregory Ginzburg (the late), Baruch Zinger and James Y. Becker Department of Chemistry, Ben-Gurion University, Beer Sheva, Israel The anodic oxidation of 1.l-dimethylallene(DMA) has been studied in acetonitrile at a Pt anode in the presence of tetrabutylammonium flouroborate (TEAF) or lithium perchlorate as supporting electrolytes. In the presence of TEAF the cyclic voltam- mogram exhibits two moderately separated waves, whereas in the presence of perch- lorate ions the waves overlap each other almost completely. The two moderately overlapping waves have been resolved into two separate ones with equal heights, by employing a semi-empirical method. This stepwise procedure is based on the assumption that each electrode process is indepenent of the other and that the rising portion at the foot of the first wave is not interfered by the second wave. - 113 - CYCLIC VOLTAMMETRY OF Pb AND Sn IN SOLUTIONS OF ALUMINUM BROMIDE AND KBr IN AROMATIC HYDROCARBONS M. El am, E. Peled and E. Gileadi Department of Chemistry, Tel-Aviv University, 69978 Tel Aviv, Israel The electrochemical behaviour of dilute solutions of SnBr2 and PbBro in a non- polar solvent system consisting of solutions of 1.0M Al2Br6 and 0.80M KBr in ethyl- benzene was studied. Cyclic voltammograms show well defined peaks for the deposition and dissolution of the divalent metal. Oxidation to the tetravalent state could not be detected in the available potential region. The diffusion coefficients were CO C O 1.1x10 cm /sec for lead and 2.7x10 cm /sec for tin, as compared to a value of -6 2 4.0x10 cm /sec for mercury in solutions of toluene of nearly the same viscosity. An overpotential associated with initial nucleation on a platinum electrode is observed for both metals and electrodeposition does not start until n reaches a value of about 30-40 mV. In the presence of lead, aluminum deposition is inhibited and does not occur until a considerable overpotential is reached. A value of c«u -70 mV RA1E is observed for a concentration of 2.0 mM PbB^. Tin, which is deposited at a more anodic potential does not exert a similar inhibition effect. The anodic peak depends on the amount of metal deposited in the previous cathodic half-cycle and cannot be used to analyze the course of the reaction. When the potential is allowed to reach a sufficiently cathodic potential to deposit aluminum in the presence of lead, a second anodic peak appears, which can probably be asso- ciated with the formation of a thermodynamically unstable Al/Pb alloy. - 114 - CALCIUM - THIONYL CHLORIDE HIGH-RATE CELL R. Tulroan, A. Golan, A. Meitav and E. Peled Department of Chemistry, Tel-Aviv University, 69978 Tel Aviv, Israel Alkali and alkaline-earth metals immersed in thionyl chloride (TC) solution are always covered by a surface layer which is instantly formed by the reaction of the metal with the electrolyte. While having a relatively low electronic conduction, this layer has appreciable ionic conductivity and for this reason is referred to as a Solid Electrolyte Interphase (SEI). This SEI apparently determines the electro- chemical behavior of these metals - thereby having a major influence on the proper- ties and performance of batteries which contain alkali or alkaline-earth anode. We recently have shown the basic different behavior between the Li/TC and the Ca/TC cell The Ca/CaCAlCKK-TC cell behaves as an "electrochemical diode", i.e. it delivers high current densities (up to 50 mA cm ) in the anodic direction (discharge) but operates as a high resistor in the negative direction, and during overdischarge (reversal test). Therefore, it is practically impossible to charge or overdischarge this cell. In this regard it should be noticed that high rate lithium cells may explode in reversal tests. This is the largest obstacle to the broad use of these cells. Laboratory prototype Csize (100 cm ) jelly roll Ca-TC cells were assembled and tested. At room temperature the cells delivered 3.5 Ah at 0.15 A and 2 Ah at 0.75 A. The study state value of the current during charging or reversal abuse tests at 25V was lower than 20 mA (lithium high rate cells would explode under these tests). Corrosion tests of calcium at 70 and 25°C indicate a shelf life of 1.5-2 years at room temperature. The transient minimum voltage at 1.2 mA cm after 14 days of storage at 70°C was above 2 volts. Kinetic measurements indicate the fact that the passive layer doesn't thicken endlessly, but it reaches a plateau. INDUSTRIAL CHEMISTRY - 115 - PHASE TRANSFER CATALYSIS; FUNDAMENTALS AND RECENT DEVELOPMENTS Prof. Dr. Eckehard V. Dehmlow, Faculty of Chemistry, University Bielefeld, Universitatsstr. 25, D-48OO Bielefeld 1 Phase Transfer Catalysis (PTC) is a modern technique of wide application in many fields of chemistry. The first part of lecture gives an introduction both into the theory and the practical aspects of interest for the person who is new in this field. Choice of catalyst, of solvent, of reaction con- ditions, methods to remove and regenerate the catalyst are discussed. A survey is given of the various reactions that can be performed by Phase Transfer Catalysis. In the second part of the lecture newer developments are in- troduced, and focus is put on the work from the laboratory of the author. The extraction of neutral molecules and acids is one of these aspects. Further reactions include those with very strong bases, eliminations, H-D-exchange, additions of acetylenes, aldol condensations, Wittig and Homer reactions, novel conversions of diketene, and others. In the resume an outlook on further developments to be expected will be given. - 116 - PROBLEMS OF SCALING UP TO JUMBO AGITATED REACTORS AND ERGONOMIC INTERRELATION BETWEEN THEIR OPERATORS AND THEIR ON-LINE COMPUTER Aldo Cantoni Electrochemical Industries (Frutarom) Ltd., Haifa, Israel When scaling up a reactor in which an exothermic suspension polymer- ization takes place, it is impossible to optimize all factors to be taken into account. The heat transfer surface to volume ratio worsens; control delays increase because of inertia phenomena; keeping the equal agitating power input per unit volume causes shears on suspended particles influencing the morphology of the polymer obtained. A compromise is thus inevitable. The ergonomics of an operator confronting the incessantly pressing requirement of an on-line computer are described. The limit of stress endurance of an operator constantly required to take decisions are discussed. Claustrophobic phenomena have to be considered, and viable approaches have to be worked out to cover emergencies of various kinds. - 117 - b\a n"D3jiD mvin '^sa D'^Tia ^m Bin in on O^DSJID mcnn {n-»D3Jia mvini asm '"SB nmip mo"»nn niD*»'or n^ioa n^DajiD mT'in n"7 TOR n i mom *7T"ia IJI3D TIOID D"DJjim9 D*»3T» "70 a' 'Tio 19DJD3 nmij n'oajiDn in D'9'mn ,n*»TnoD nnsa OT*n n ona D'^OS'T D'DDna DICD nssin IT n3TDn ."7TT33 n niD main 'noua RDjmV .TTDDO1? mom i">a T»DS7 mi'DS DDR TST3 131 Tp1? TSH 1 "»3 TIBJlD *7T13n IlTTp ,1'no 'R*?aD "?aion *?aipD iiD'n DDR nDis7*7 mmaa aia'o rn n D'spnoai mu mp-«5n nionsna O'DID-'O! HT ^TDD lion 'spnoa oa D'ODOD O">'B3JIO D'^TTS .nnpino Jt1? 'D3JID iTTD n*7SSn DB DH3 1S13H Tn"7 OSK'TTJl D'03 *7P n snM '03 JIB K1? 10 in "73 TSn1? in">3 n"7R 01)'7T133 . "»3J1Din T O'linD DT"3 D^OSAD D'^TIS "JD D^inODH D'BlD'Bn "»D HRT3 . T?R D'^TIS "?o nnn mi - 118 - an a ,IIMI .n ,qinj»B .n n •> s p n in n>n»n no>ana nD*iyn *ii^ ramp nmayn nnniaw ira^ana an nn^oo nannu>K ^a na n>a>ana an n.-l q. = K.C. [X a..C.] 1 1 i»n n. -i Ki nn^ao >j?iap .Van nanmnKb ns * ia»Knn ni'^io^a immn m nanyaa >u ba may i^apnnw aj^. nmnn »anpn I^'KI a>ana bi bv n»a"»ana nn .n»a»ana nbt\ nanya cat G<^a<.cu' cut a* C^LL. tci, cutL uass axtuui cttu dal ( dLau=9*i. a,,a )• QtdLlOdLG, H^daLLE* QlLd (*W*3*S ) 'CtOtlClU UX^U a^GflLLU HU dCt&I UUG^ttua ffl^ 4QLLLU Liac*. cumLfca a«.ai! ui.au ^uccu uda^aa ^»iu uu^mucU 4^44 tcL4du uda^toa c£4i.u HO aLi.il 0o00V 'VlV UtLCli ^ LSLtU cu uda^ta«.u ( as uurictu 4M1L U4i«LL4iJ n UQ4CU C4 n ut ml dita ^^ ; urtcu jjau QULUAU cdru # ctci. 5(J4 r^Lau LdaLuwa am. auLLta dai^a tjui. XUL a^ a^ «sU4 uas4 a^ x^ict4tu da^^atu* U4» uncu UttCU XL „ UQCC4C 1JUUC(.XU4 N/BL Ct,,C UQZS ( LCL, )* QtT uricu GQit tscut ajnssoxo 3in;.i pus uaucu4 ( G^CUCU' G^L4ta* LC4LQ4 utactta tct, )* uuxicu u&t*u L'*n urtcu uricLU u^d4tu uauLuam cdu L£iru xuu* UTLCU »UU ( tuxLLTtxtu KL i.u*Ltircx4U ) LUtU (S,,4 dQ^tOQ C£^ UGd4L CGL^* oi, <>4uu UQL^I u.Ncr^* puog*o*0 u«.utL4U UL&U ^uacuu urtctu CLS^L: ^iC4CLQ4au cl ttuttl cere* uactl ^audu UJtXLLtli 0^ CLCL (QHOff-) ' aaau;Ll 0 - 6X1 - - 119a - 1 Cr 2 Pt jn n»npn ma^snnn n*c mtnb -IWSK nVapnn -TOK •(line scane profile) L«S#P, «a (1) n'anoin sV rnaVsnr. rDins TTS? S.LOP. n eyoo maVsnn taa^DVs -nay S.L.P. —D .-inT» p*no3 CIDD no» Vc? imaVDnn ns 7"DKV '•na wrn »pna JWID oaain npnon n'amon maVsnn Kin winn awion «( *wKnn 3»DID ) jnjn mpaa nj^cVsn ^c nmaVsnn !?y nan leas n»rmp3 IK ir»aman niiVsnn ns .nV"»ann n'npn maVsnnno naiwn ,n»mip3 IR 1 nuVsnn nms ^ya nain *ni? 7*»2 D'Vian^ fnan ? I-DK PTI TJT»^ ,^is'on nmcn: ^ na'uVsn VTO nnmcn na^annr; iccana ^n i*»Vnn2 atnnu ms^nr. ^K Vo nn Vw mxpaisa D'ITO nmay ^Kjna naiann >E? m'ua'pn niKsinn ntisio n isioa n»iVn ivy. na'oVsn VP n'impa IK n»amz>n - 120 - 0 Converting of alkyl chlorides to alkyl bromides by PTC Influence of PTC ofi equilibrium position of reversible reactions M. Weiss-Yonovitch and Y. Sasson The Casali Institute of Applied Chemistry The Hebrew University of Jerusalem Halogen exchange reactions between inorganic halides and alkyl halides (Finkelstein reaction) are equilibrium reactions and are not effective for converting alkyl chlorides to alkyl bromides since no simple methods are available for shifting the equilibrium in the desired direction. The present work has utilized the technique of PTC for synthesis of alkyl bromides from alkyl chlorides and aqueous or solid bromides with quaternary ammonium salts serving as PT-catalysts. This work also demonstrates how PTC may influence the equilibrium position of reversible reactions. A typical process may be interpreted by the following equation: p ri + 1 raB-r The reactions were carried out in a two-phase system at temperatures of 90-130°C. In typical examples benzyl chloride was efficiently converted to benzyl bromide, allyl chloride to allyl bromide, dichloromethane to chlorobromomethane and dibromomethane, n-octyl chloride to n-octyl bromide. Parameters such as temperature, rate of stirring, solvents, concentrations of CaBr- in water and its quantity, and also the catalyst structure and its concentration of the quilibrium position and the rate of the reaction have been investigated. - 121 - 0 GAS PHASE HALOGEN EXCHANGE IN ALKYL HALIDES CATALYZED BY SUPPORTED MOLTEN PHOSPHONIUM SALTS L. Mendelovici and Y. Sasson Casali Institute of Applied Chemistry The Hebrew University of Jerusalem Exchange of chloride by bromide was achieved by passing mixtures of alkyl bromide with alkyl chlorides over supported quaternary phosphonium salts. Typical active catalyst was prepared by supporting 5-10Vw/w tetrabutylphosphonium bromide on alumina. By passing, for example, mixture of ethylene dibromide and ethylene dichloride in a tubular flow reactor at 150° over this catalyst equilibrium conversion can be obtained at space velocity up to 1500 GHSV according to the following equation: S: BrCH2CH2Br + ClO^OLCl ^= 2 BrCH2CH2Cl This method will allow the application of EDB as a bromination agent for production of simple alkyl bromides from the corresponding chlorides in a flow system. The Following mechanism is proposed: C1CH,CH,C1 + QBr F=* ClCH,CH,Br +-QC1 22 k2 . . ' BrCH CH Br + QC1 *=^ ClCH7CH9Br + QBr k4 L L , .. . This mechanism is in accordance with the following apparent rate equation: rate = kC2 - k'.(Co - C)2 where k = k' = — 2(k2+k1+) C = [EDC] Co = [EDC] 'o Details regarding the mass transfer effects, thermal stability of the catalysts: and the role of the support were also investigated. - 122 - 0 FLAME RETARDING PROPERTIES OF THE BLOCK COPOLYMERS OF BROMOSTYRENE (BS) AND STYRENE (St) Itzhak Koenigsberg and Joseph Jagur-Grodzinski Department of Plastics Research The Weizmann Institute of Science, Rehovot Flame retarding properties of block copolymers of BS and St have been found to be superior to those of their random copolymers and of the blends of the res- pective homopolymers. Block copolymers were prepared using the anionic polymeri- zation techniques (1). Side reactions, due to the susceptibility of the C-Br bond in BS or in poly-BS to nucleophilic attack (2-4), were avoided when the polymeri- zation reactions were conducted in dark at -78°C with "living" carbanions as initiators. Polymerizations of BS were completed within few seconds and high molecular weight polymers with narrow molecular weight distribution (Mw/Mn = 1.04) were obtained. Controlled elimination of bromine leading to the formations of the polyphenylacetylene segments was induced by keeping the unquenched "living" carbanions in dark at -21°C. PS + PBS . , ^ Random PnoS ,,, ,. DBlock copolymers , nDPBCS (blend) _____ copolymer Fraction of none 50 31.5 35 43 52 100 PBS (W%) LOI^ 17 21 23 24 27 24 38 (a) According to ASTM Standard D-2863/77. LOI indices summarized in the table indicate that BS in the block copolymer is more effective than in the randomly distributed copolymers or in the blends of homopolymers. Apparently, spacial distribution of the BS domains may affect significantly the flammability of the material. References 1. M. Szwarc, Carbanions, Living Polymers and Electron Transfer Processes, Wiley, New York, 1968. 2. CD. Sargent, Tetrahedron Letters, 3729 (1971). 3. J.F. Bunnett, Accounts Chem. Res., lj^, 413 (1978). 4. W.J. Trepka and R.J. Sonnenfeld, J. Organomet. Chem., 16_, 317 (1964). - 123 - 0 THE CHEMICAL HYGIENE OF PROCESS SOLVENTS II. SYSTEMS CONTAINING TERTIARY AMINES L.M. Shorr, J. Segal 1 and Z. Blutstein IMI - Institute for Research and Development A primary requisite for a process solvent in the manufacture of large volume industrial chemicals is its chemical stability. Decomposition not only represents a material loss, but contaminants produced in even very low concentra- tions can cripple process operations. Reactions which proceed at a rate of only a few percent a year receive little attention in the chemical literature. Long chain alkylamines find extensive industrial use as liquid ion- exchangers, extractants in hydrometallurgy and the recovery of acids from both aqueous process and waste streams. On the other hand, the anti-oxidant activity of the amine function suggest a decomposition pathway which might interfere with the performance of industrial solvent extraction operations. The oxidation chemistry of tertiary amines, examined for use in such applications is very complex. Oialkylamines, aldehydes, enamines, formamides, olefins, hydroxyamines, amine oxides and various condensation products can form. The extent and nature of the reaction in any given solvent stream is influenced by its composition and the conditions to which it is subjected. An overall scheme, descriptive of the chemical breakdown process was evolved. The measurement of oxygen uptake rate was found to be both a simple and sensitive tool for the evaluation of the susceptibility to oxidation of any given amine system. - 124 - 0 -njpn pip*TO n^pyn , i omn smya p bench-scale 'mnyn nnjp3 Q>»io>jn >K?»n o»nm» ibbs o»3»^win .oaji^ pipT 'nn >3SB !?i£>u t>y ipnn ni>onn pilot plant CD«A.F) onin bv nnK 90 D npmn D>*te?3N0 onia miayn .ooia VIK n^xoi^a oy nKiiwr naiyai Tmin n»u< n^^oiba i»bnn D> npnin bv ni^A nprnn Tin O>>JAIIKI D>^uo*pn n^oniy bv an*i oinnn nnK 90 - 125 - 0 INFLUENCE OF CHLORIDE IN PHOSPHORIC ACID ON THE CORROSION AND ELECTROCHEMICAL BEHAVIOUR OF IRON AND NICKEL ALLOYS M. Schorr and E. Weintraub, IMI-Institute for Research and Development, Haifa. Phosphoric acid is an important industrial chemical used as an intermediate in the fertilizer industry, for metal surface treatment in the metallurgical industry and as an additive in the food industry. Wet process phosphoric acid (WPA) is produced by attack of sulphuric acid on phosphate rock. The composition and purity of WPA depends upon the composition of the rock and the sulphuric acid used. Impurities such as chloride ion, arising either from the rock or the wash water, fluorine compounds originating from the fluorapatite, and the operating conditions^ , increase the corrosivity of WPA during the production stage. The influence of chloride ion on the corrosivity of 42%, 55% and 70% H_PO. has been investigated by corrosion tests in H_PO. solutions containing chloride ion in the range 0.05-1.0% Cl . Corrosion tests we.re also carried out on filter and concentrated acids obtained in industrial and pilot plants. The corrosion and electrochemical behaviour of AISI types 304 and 316 and high-alloyed austenitic stainless steels and Ni-base alloys, in Cl-containing phosphoric acid has been determined by weight loss measure- ments, by measurements of metal electrode potential as a function of immersion time and by potentiostatic anodic and cathodic polarization, in the temperature range 70-120°C. The alloys tested exhibit passivity in solutions of pure H P0. but in the presence of Cl ion breakdown of the alloys' natural passivity occurs with the onset of active corrosion. The electrode potential of the alloys shifts,from the passive to the active state, at a rate and magnitude, directly related to the Cl" content of the H P0. solu- tions. The values of the electrochemical parameters of the potential-current plots reveal anodic dissolution or passive behaviour, and vary in accordance with the Cl concentration and the corrosion rate. Results from gravimetric and electrochemical tests will be presented, the types of corrosion will be described and their practical significance will be discussed. REFERENCE 1. M. Schorr, Corrosion Manual, Part One: WPA, Corrosion Testing and Control in Fertilizer Intermediates and Products, IFDC, Muscle Shoals, Al. (1981). - 126 - 0 WATER AND SALT TRANSPORT THROUGH AN ION-EXCHANGE MEMBRANE T,S. Brun (present address: Chemistry Dept., University of Bergen,Norway),and A. Berg (present address: israel Desalination Engineering,Tel-Aviv, Israel) Michigan Technological University, Houghton Ml, U.S.A. Linear non-equilibrium thermodynamics provides membranology with a useful means of analysis of transport processes. For transport through membranes, Onsager's relations between fluxes and forces, which are of general nature, seem to hold quite far from equilibrium and can therfore be applied to many practical process- es. Michael i and Kedem (i960 adapted Onsager's(J.=£ L. .F.)equations to a simple membrane/solution system. Schmitt and Spiegler (1975) used the Michaeli-Kedem equations to produce a set of equations that enables the calculation of the conductance coefficients Lx y , which characterize the transport Behaviour of the system. Five groups of measurements are necessary to provide the experimental data needed for the cal- culation of these coefficients, viz. (•) membrane electrical conductivity; (b) electromigration-electroosmosis; (c) osmosis-dialysis; (d) hydraul?c permeability and (e) streaming potential. All of these experiments but the first group can be performed by the "concentration clamp" method developed by Spiegler and Colleagues since the late 196O's (A. Zeiman et al. (1971)). Further development of the system was achieved by simplifying the apparatus which allowed shorter experiments and easier salt-concentrat ion control in one solution compartment. Quantftfve characterization of the system M r, . . , I Cation exchange membrane I atl solucion c s |CL-25T (Tokuyama Soda Co.) | NaCl solution c"s demonstrated the usefulness of the modified method. The results obtained were compared to the results of studies with the membrane C-103, (American Machine and Foundry Co.). The "diagonal" (Onsager-type)conductance coefficients of the membrane CL-25T were found to Be larger than those of C-103, which indicated higher permeability. Onsager reciprocity relations were validated in the studies with both membranes. REFERENCES 1. Michael i, I. and 0. Kedem, Trans. Farad. Soc. 57J185 (1961) 2. Schmitt, A. and K.S. Spiegler, unpublished results (1975) 3. Zelman, A., J.C.T. Kwak, J. Lfebovitz and K.S. Spiegler, Experientia Suppl. J8., 676 (1970 ACKNOWLEDGEMENT Prof. K.S. Spiegler, from the University of California, Berkely is highly app- reciated for leading and guiding this research. - 127 - 0 SIMULTANEOUS REACTION AND DISTILLATION IN A PACKED COLUMN R. Neuman and Y, Sasson Casali Institute of Applied Chemistry The Hebrew University of Jerusalem Most industrial reactions and separations take place in different zones whereby reactions are first completed and then products are separated, e.g. by distillation. A significant savings in equipment and energy can be obtained by conducting both reaction and distillation in the same unit. We have studied the continuous esterification process of diluted acetic acid with methanol to yield methyl acetate according to CH3COOH + 70H CH3COOCH3 H20 (Keq =5.4) The reaction was carried out in a six theoretical plate-column packed with a combination of solid catalyst (acidic ion exchanger) and regular column packing. The conversion and the purity of the product were measured as a function of reflux ratio, feed concentrations, location and rate and quantity of catalyst. At optimal conditions up to 98% conversion could be obtained with 1001 purity. A mathematical model was built which takes the rate equation of the reaction along with thermodynamic properties of the system components and physical variables (reflux ratio, feed rate and location etc.) and calculate the conversion and the purity of the products. Quantitative data will be presented in the lecture. - 128 - 0 Crystal Structure Modification of Saturated Fats by Food Emulsifiers by: Edna Wellner, Nissim Garti, Sara Sarig. Casali Institute of Applied Chemistry The Hebrew University of Jerusalem Ordinary, molten fat when cooled will crystellize in the metastable ot-form. This form transfers during storage into the more thermodynamically stableB-form. The polymorphic transformation can cause texture problems in the food industry based on fat. The present work investigates the effect of several emulsifiers as crystal structure modifiers,in preserving theo(-form of pure tristearin. X-rays powder diffraction and D.S.C. techniques were used in order to evaluate the emulsifiers effect. It was shown by both techniques, that when 5wt. % of SPAN 60 (sorbitan monostearate) were added to the molten tristearin before cr/stallization theo(-form did not undergo phase transformation into the f^-form and most of the fat consisted of the original modification aven after prolonged self life storage. Increasing the amount of the emulsifier to 15%, prevents any transformation from ad-form into the &-form. Several pther emulsifiers have been tested and it has been found that the combination of bulkiness of the hydrophilic groups with tke right lengths of the hydrophobic chains of a given emulsifier are necessary to preserve the oC- modification. Liquid emulsifiers and those having a pronounced hydrophilic character will not be efficient as crystal modifiers. - 129 - 0 Emulsifiers as Weighting Agents By: Z. Kraus; M.Frenkel; N. Garti Casali Institute of Applied Chemistry The Hebrew University of Jerusalem. Emulsions are inherently unstable, meaning that in the course of time droplets will coalesce and ultimately water and oil phases will separate. Coalescence is accelerated when there is a difference in specific gravity between the two phases, promoting creaming which will concentrate the droplets. In a case of oil in water (O/WJ emulsion, where the oil is lighter than water, oil droplets tend to rise to the surface of the emulsion. The final step-coalescence, or breaking of the eimilsion, involves the merging of the droplets to form larger clusters and ultimately a complete destabilization of the emulsion occurs. The creaming phenomenon can be prevented by equalizing the specific gravities of the oil and water phases. A new concept was developed at the Institute which combines the Weighting and emulsifying functions in one cpmpound. An example ii the use of bromination to increase the specific gravity of commercial surfactants. Various commercial emulsifiers, both ionic and nonionic were bronlnated and the physical properties (e.g. specific gravity, Iodine number, Acid value, I.R) of the new compounds were determined. Their surface properties', such as critical micelle concentration (CMC), surface excess concentration (P), area per molecule (a), efficiency (PC,J and effectiveness, were examined and found to be slightly lower than the unbrominated ones. Eventhough, these new surfactants proved to be useful emulsifiers by using them for the preparation of most stable 0/W emulsions. By using proper amounts of the new emulsifiers-weighting agents the specific gravity of the oil droplets is equalized to that of water. No creaming occurs in such a system. Larger amounts of these emulsifiers - weighting agents in the system (3.5wt.\ . of the nonionic emulsifiers, 1 wt. % of the anionic emulsifiers) increase the specific gravity of the oil droplets to values higher than one. Consequently, sedimentation (rether than creaming) occurs, being a substantial proof of their weighting property. - 130 - 0 Dispersing Agents in Aqueous and Organic Systems By: H. Isaacs, N. Garti and M. Frenkel Casali Institute for applied Chemistry The Hebrew University of Jerusalem The action of dispersing agents for solid particles in a fluid medium has long been a matter of trial anf error based on very limited theoretical work. In this series of experiments an attempt was made to systematize the interaction of polar and non-polar solids and fluids, with the effects of different types of dispersing agents on each. The polar solid was calcium carbonate and the organic solid was polyvinyl chloride. Liquids were water and heptane. In each case a 50% by weight slurry was prepared and its viscosity measured with incremental' additions of various dispersing agents. In this way it was found that sodium lauryl sulfate is a very effective dispersant for PVC in water but a very poor one for calcium carbonate in water. Tamol 731 is quite effective for both. Lecithin is effective for both materials in heptane, while Tween 80 is a dispersant for PVC in heptane but not for calcium carbonate. The results were explained by the tendency for the dispersing agents to be absorbed on the particle surface and electrokinetic potential changed. Further work should enable the choice of optimal dispersants in paint formulation, wastewater treatment and paper coating. - 131 - SYNTHESIS OF DIALKYLPHOSPHORIC ACIDS FROM P0C13, P2O5 AND ALCOHOLS J. Segal 1, L.M. Shorr and S. Weiner IMI (TAMI) - Institute for Research & Development, Haifa Dialkylphosphoric acids are of commercial interest mainly for metal extraction and as industrial intermediates. They are commonly prepared either from PpO,- or from POC1- and the respective alcohol. In both cases monoalkylphosphoric acids are co-produced and tedious separations are involved. By using equimolar amounts of P20c and POClg, generally in the presence of an amine, followed by the addition of an alcohol, a variety of essentially pure dialkyl- phosphoric acids were prepared in approximately 90% yields. It is assumed that pyro- and/or-polyphosphoryl chlorides are the intermediate species from which the dialkyl- phosphoric acids are formed. - 132 - P Preparation of Monoglycerides of Fatty Acids from Epichlorohydrin by Phase Transfer Catalysis - Part I By: Y. Sasson, N. Garti and A. Aserin Casali Institute of Applied Chemistry School of Applied Science and Technology The Hebrew University of Jerusalem 91904, Jerusalem The existing industrial reactions for preparation of monoglycerides of fatty acids are based on acidic or basic catalysis at elevated temperatures and prolonged reaction time. The product is an equilibrium mixture of isomers which needs further expensive and tedious molecular distillation. The following study presents a suggestion on a new selective method for preparation of pure monoglycerides of fatty acids. The reaction is based on treatment of epichlorohydrin with sodium stearate soap in the presence of various phase transfer catalysts. Over 90% of pure monoglyceride is obtained in quantitative yields after short reaction time at relatively low temperatures. The effect of reactants ratio, catalyst type and concentration, temperature and industrial aspects have been investigated. - 133 - P Multiple Emulsions: A Novel Technique to Overcome The Unpleasant Taste of Drugs R. Shwartz, M. Frenkel and N. Garti The Casali Institute of Applied Chemistry, The Hebrew University, Jerusalem A multiple water-in-oil-in-water emulsion (W/O/W) is a water-in-oil emulsion which is further dispersed by the aid of proper emulsifiers in a second aqueous phase. This emulsion contains water droplets (0.1 - 2*m) which are surrounded by an oil membrane. In OTder to mask the bitter taste of a drug, it must remain in the inner water phase since preparation ("Yield of Preparation") and for its total shelf life ("Stability"). Furthermore, the drug should be completely released upon reaching the stomach. Many W/O/W emulsions were prepared using ionic and non-ionic emulsifiers. Their suitability for use with the drug (chloropromazin hydrochloride) was examined. The yield of preparation and stability of the various systems were tested by dialysis of the multiple emulsions and by quantitative analysis of the drug. By using non-ionic emulsifiers the yield of preparation did not exceed 85% Cleaning that 15% of the drug is present in the continuous aqueous phase) although stability was 100% (no further drug was released from the inner phase). The optimal solution was found by using a combination of ionic and non-ionic emulsifiers. The results obtained were: Yield of preparation of 100%, storage stability of 100% and total release of the drug in synthetic gastric juice. - 134 - EXTRACTION OF ALKDXIDE IONS BY LIQUID ANION EXCHANGERS E. Pross and Y. Sasson Casali Institute of Applied Chemistry The Hebrew University of Jerusalem When organic solutions of lipophilic quaternary ammonium salts (liquid anion exchangers) are treated with aqueous caustic solutions only negligible amounts of the hydroxide ion are extracted into the organic phase. The behavior of this anion is thus different from other anions, namely halides, perhalides, nitrate, etc. which are easily extracted under similar conditions. This observation is changed when small amounts of primary alcohol is added to the system. Very strong bases are obtained in organic media when 50% aqueous sodium hydroxide is extracted with toluene solution of tetra-n- hexylammonium bromide containing 2-5% of alcohol, e.g. ethanol, n-propanol, n-butanol or benzyl alcohol. Based on quantitative measurements we propose the following mechanism to describe this phenomenon: (1) Distribution of the alcohol between the organic and the aqueous phases. (2) Acid-base equilibrium in the aqueous phase according to: + ROH + NaOH ?=* RO~Na + H20 (3) Extraction of the alkoxide ion with the quaternary salt by anion exchange: Q+X"(org) + R0"(aq) =s=* Q+OR(org) + X"(aq) where Q is the quaternary cation and X is its original paired anion. A suitable parameter to describe the extractability of RO" relative to that of X" is Ksel defined by: M DQaq [0X]org [RO-]aq This constant was measured for several alcohols and its magnitude implies that alkoxides can be efficiently extracted by various combinations of solvents and quaternary salts. - 135 - rniy3 n Vo? (crystailinity) nr>p jiaan ,aaaa T»KB (A100H) nnapV na aaanV 7n*an "\x , (tr»Dpitta a^ana) yaoa KXBX *TOK 9 (Bohmite) naanV nni»a aiwin oVa nain icm •v*opiKan V a»anaa j?aca p-y KXBJ (Diaspore) msoK-»T .2 oa (crystallinity) njr»ap : nsoa (shifting) p-»sn nnon ,o-»-»sipona»nn o'an 7a Z.R.D Van "»xn Vc ami naan —in nysin oa :IVK mys maipya jr»sia TWK t(n*opm*n-*DpiKn V© *mnn pn»sV ncrpa n&s) •pKnn p»sn Vw K»E7n nnDT? - *n •^n^•» nnon , J),T.G, T D.T.A. D.T.G, n D.T.A. moippa w Vr ^<»^Da'>cK^ - IT nairm oa .p'sn ) »win p-»sn "npnipav? n»iTn Vma - . K-\ .isnVn jwna'an ima naopn Dy nVnai nsVm IT n»iT.D,T#G. i D#T»A, niaipya *WT» mp»ia «aan Bi»*na wia^an m*aa mVna nanwo IT II'ITH Vniaw Kxoa HT ipna nVnaa via*an m*aa o*"»ia*roV it n»it »"»ia»w Vn? mwanrtw in*ain ,naiw cia»a IIT»D mVya moan 20 a oniKa lysia n"»ann HT'VJK V© mp»iaa .iVw n»ni3D»cKD IK p»s irnt; bv innono mv nmaa K'n *l*iana . D,T#A#a oa V»apaa npiaa »Kaan Va .mKxmn nK rnwnV n"»a» ^n^aw *ia miay *»Kan •Van *sn Vw ann oa yapa CULU r*cta rcmu C«.CLC*U caicu / 0. OVS sdiaiu UU2tU GtXt ^ LLUC US* ut^» ^ ZULCU Si. Lt*- I.S.I. ISRAEL SCIENTIFIC INSTRUMENTS LTD. TT01 TtOHn 'DID 1WDD 52 306 ll|Tn 341790-.OP^U 772051-2-3^U |A-nm,17 OniD 3im VISTA 6000 Gas Chromatograph The newest, most advanced, most accurate GC available today. Based on world reknown 3700 series. - Dual column standard, up to 4 simultaneously option. - Specially adapted for all modern capillary column techniques. - Microprocessor, preprogra- mmable, auto zero, auto injector and many other TO BE SEEN IN ISRAEL IN MANY PLACES IN WORK state of the art'features. Ask us about the new HPLC Detector UV-100, scanning, programmable and very small. APA AM ADVANCED TECHNOLOGIES LTD. irui mmpnn ni'Mmo NQN TEL. 03 -226788.222691 ."7U TELEX: 32366 Rial il.: Dp^U 61211 D'ON-to 21205.1.11 P.O.B. 21205, TEL-AVIV. ISRAEL DESIGN YOUR HPLC SYSTEM WITH WATERS MODULES HPLC FOR ANALYSIS OF: O ORGANIC SYNTHESIS O PHARHACEUTICALS O POLYMERS/ADDITIVES O ADHESIVES/COATINGS O ENERGY O ENVIRONMENT O HOSPITAL/CLINICAL LABS O BIOLOGICAL/B1OMEDICAL O FOOD O AGRICULTURE MILLIPORE Waters, The Liquid Chromatography People LACHMAN PROCESS EQUIPMENT LTD. nwV3 •3'^flXl 1VX P.O.Box 1308 47100 Ramat Hasharon Israel 47i00im>nnm 1308 .7.n LPE LIGHTNIN ,na->Kip PUlSAfeeder nnsni mm on RUBBERco BIRD .5 31DT13 'm 7\22y\2 052 - 37163 TTSVO iNiiETilil m 471CX) mwn nm ,1308 .T.n PUMPEN MEDTECHNICA LTD. 'DQIX .THIlLm ,^131 1VX T2X-'7T\ 8 Dl7Wn 111 61 026 HWTi 2695 "rn TEL. 331263-8 7D pH LDC/Milton Roy _ HPLC-1? m'i?mo mDiyo IDR TittDO - ULTRA VIOLET PRODUCTS,IINCnn® San Gabriel. California 9177fliyj C^LiMIEJ: INSTRUMENTS COMPANY .91010 Q^IJIV,222862,222059.i>0 ,1147 .T.H 12 26147 ^ DESAGA- SCHOTT: TLC, Isoelectric Focussing, 20 and 48 Fraction Flow 5 Immunoeiectrophoresis, UV lamps, Peristaltic Pumps,pH Electrodes,Viscosimeters, Titration and other laboratory ware. NUCLEAR ENTERPRISES: Sample counter (96 samples counted in six minutes).Nuclear and Health Equipment. CEPA : All-purpose Laboratory 5 Industrial centrifuges. SARGENT-WELCH: All kind of laboratory ware § Vacuum pumps. TOWNSON 5 MERCER: Laboratory § Pathological ware. SHANDON: GALLENKAMP: Comprehensive range of laboratory ware. JENCONS: Water Stills,Homogenisers,Pipettes,Dewars, Dessicators. ELECTROTHERMAL: Heating Mantle/, Tapes, Laboratory ware, New Model Fraction Collector ( 500).Gradient Formers, etc. OHAUS SCALE CORP: Manual and Electronic Balances. TINTOMETER: Spectrophotometer Cuvettes, Colorimeters, Water Tests. WHATMAN: Filter papers, Glass-Fibre Micro Circles, Ion Exchange, Membranes,Cellulos-Separations, Columns, Media for HPLC. WHEATON: Laboratory Glassware bottles § Industrial Equipment. BIO-RAD: Chromatography, Electrophoresis, Hollow Fiber, Columns, Membrane Filtration § Immunochemistry. WOELM PHARMA: Alumina, Silica-Gel, Glass § Aluminium Precoated plates. Glass, Porcelain, Plastics, Pathological Ware, Flow-Meters, Stoppers, Dewars, and Chemicals. ANALYTICAL CHEMISTRY - 136 - THE ANALYSIS OF SEAWATER FOR TRACE METALS - A CHALLENGE TO ANALYTICAL CHEMISTS S. Berman, Division of Chemistry, National Research Council of Canada, Ottawa, Canada, K1A 0R9 The analysis of seawater for trace metals has long been a challenge to analytical chemists. Problems are the inherently low metal con- centrations (submicrograms per litre), the complex matrix containing up to 3.5 percent dissolved solids, as well as sampling and storage. This laboratory, under the auspices of the National Research Council of Canada's Marine Analytical Chemistry Standards Program, has over the last few years developed a series of procedures for concentra- tion, separation and determination of a number of trace metals in seawater of interest to marine scientists. These include methods involving chelation-solvent extraction, ion exchange chelation, immobilized ligand chelation and determinations utilizing atomic absorption spectroscopy, inductively coupled plasma - optical emission spectroscopy and isotope dilution solid source mass spectroscopy. A highlight of this work is the recent production of the first seawater reference material for trace metals, NASS-1, which is now being distributed internationally. - 137 - ANODIC STRIPPING ANALYSIS APPLIED TO ENVIRONMENTAL SURVEILLANCE Magda Ariel Department of Chemistry, Technion - Israel Institute of Technology, Haifa. Anodic stripping analysis and its advantages for trace metal analysis in a variety of environmental matrices and in particular natural waters are discussed. Recently developed approaches and instruments, which enhance the technique's capabil- ities, are described. The survey includes subtractive methods based on the use of different deposition times or different convection rates at twin matched working electrodes dipping into the sample cell; flow-through cells for the analysis of a succession of discrete samples or the in situ monitoring of traces of heavy metals in aqueous samples, using rotating disc electrodes. A combination of a specially designed flow-through cell with fixed mercury film glassy carbon disc electrodes, used in the differential anodic stripping voltammetry mode, is shown to provide a simple, stable and precise tool for the automated monitoring of sea water samples. In the 10- 8 -10- 9 molar concentration range, 1-5 min deposition times suffice for lead, copper, cadmium, etc. determinations (s.d. 4%), total analysis time per sample ranges from 2 to 6 min. This efficient sample through-put (10-30 samples hr ) allow reliable in situ monitoring to be carried out, using a relatively simple, inexpensive experimental set-up. (Withdrawn) - 138 - 0 THE FORENSIC CHARACTERIZATION OF PAPERS BY THE MEASUREMENT OF CELLULOSE CRYSTALLINITY by H.A. FONER The Geological Survey of Israel, 30 Malchei Israel St., Jerusalem. and N. ADAN Criminal Identification Department, National Police Headquarters, Jerusalem. The identification and characterization of different types of paper is of obvious use in forensic science. The main constituent of paper is cellulose fibre and the degree of crystallinity of the latter is a function of both the specific raw material and the manufacturing process. The degree of cellulose crystallinity was measured using X-ray Diffraction Spectrometry (XRD). A special holder was developed for cutting down background reflections and the technique is rapid and non-destructive. With a suitable XRD spectrometer the method may be used for large or small samples. Cellulose is characterized by a diffraction pattern containing three distinct peaks at 22.5°, 16.3° and 14;5° (29), (Cu K radiation). As the cellulose fibre is degraded (e.g. mechanically in a paper-making machine) the degree of crystallinity is reduced causing corresponding changes in the XRD pattern. The measure of crystallinity chosen in this work is the Crystallinity Ratio defined as:- C.R. = *J - "Slui IMax ~ """Min Where I and I . are the intensities of the 22.5 peak and the 19 minimum respectively on the diffractogram. Experiment shows that the crystallinity ratio is affected neither by the thickness of the sample nor by its orientation in the spectrometer. Results on a variety of documents show that the suggested technique is a useful addition to the more conventional methods of paper analysis. - 139 - 0 A.LORBER and Z. GOLDBART Nuclear Research Center Negev Elimination of Drift from Analytical Signals in Multielement Analysis by the GISM (Generalized Internal Standard Method) Internal standard is added to samples during analysis to stabilize analytical signal in emission spectroscopy, by refering to the ratio of signal to standard as analytical signal. The method was used widely in emission sources as d.c. arc and spark, but to a limited extent in the relatively new sources ICP and DCP. The internal standard method needs however a pair of spectral lines having similar physical parameters. When simultaneous multielement determination is performed, the error might increase instead of decrease due to variety of spectral line parameters. A method for correction of drift based on few internal standard will be presented. Experimental data shows,reduction of drift from 10% to 0.1% using ICP emission system. The spectral lines were chosen non dependent on physical parameters. - 140 - 0 Determination of Carbonate/Bicarbonate Ratio by C NMR Raphael Bar* and Yoel Sasson Casali Institute of Applied Chemistry The Hebrew University of Jerusalem Summary A linear relationship between the molar fraction of carbonate- bicarbonate in an aqueous solution and the chemical shift of the C n.m.r. peak has been established. This phenomenon was applied for the determination of the sodium carbonate/bicarbonate ratio without and in the presence of other salts, as sodium formate, sodium chloride and potassium nitrate. The method is applicable to solutions where the overall carbonate concentration is known and it yields errors of carbonate molar fraction between 1.81 and 2.8% which may be reduced by a more precise n.m.r. system. - 141 - 0 MICRO DRY ASHING FOR TRACE SELENIUM DETERMINATION IN ORGANIC MATRIXES Dr. E. Shoeriberger, J. Kassowitz National Physical Laboratory The Hebrew University of Jerusalem Since the 50fs it has been known the importance of selenium for normal plant growth and functioning of animal organism. Apart from the overall bene- ficial biological role of selenium, it was established that this element plays a protective role in poisoning with heavy metals C1U. At present, sodium selenide is used at doses far below toxic in many coun- tries in breeding farms for prophylactic and therapeutic purposes. A great deal of application work has been published for the detection of selenium on a variety of matrixes, as water C2D, waste water C33, and biological materials Zkl. The small amounts of selenium present in environment and his volatility, complicate the determination. Selenium is lest almost during every pretreatment procedure known till now CUD Determination of ng amounts of selenium in mg amounts of organic matrixes was studied, using a flameless AAS method. Chemical interferences due to the organic matrix was eliminated by working out a micro dry ashing method, using an ethanol solution of magnesium nitrate as ashing aid. The ashing was performed, after a preliminary drying step at U50 C in a muffle furnace for 2 hours. To prevent the volatilization of selenium, nickel nitrate was used as a stabilizator aid. The detection limit of the method: lOng / lOmg sample, dissolved in 500 L 0,1 M nitric acid solution. Ill EWA M. BEM: Env. Health Perspectives 37_, 183, 19-81 C2I1 EARL L. HENN: Anal. Chem. kj_ (3), U28, 1975 C3D TH.D. MARTIN, R.D. EDIGER: A. A. Newsletter 1*4. (5), 109,.1975 [In Analytical Methods Committee Analyst (London), lO^t, 778, 1979 C5D D.C. REAMER, C. VELLON: Anal. Chem. 5_3, 1192, 1981 - 142 - 0 Application of the Inductively Coupled Plasma for the Quantitative Analysis of Geological and Related Materials I.B. Brenner, I. Gal, H. Eldad, L. Halicz and D. Hoffer Geochemistry Division, Geological Survey of Israel The production of industrial materials, commencing with exploration of potential sources of raw materials, their beneficiation and processing poses numerous analytical challenges. A description is given of the use of an inductively coupled plasma multichannel vacuum spectrometer in the quantitative analysis of geological (phosphates, clays and carbonates) and related industrial raw materials (cements, fly ash and silicate refractories) for their major and minor element composition (Si, Mg, Ca, Al, Fe, Mn, Ti, P and S). Inductively coupled plasma-atomic emission spectroscopy (ICP-AES), a relatively new analytical tool posseses unique physical properties which in practice are expressed as high precision, wide linear dynamic range of the calibration curves, relative freedom from matrix effects and high powers of detection. Solid samples are dissolved by a variety of conventional acid and fusion dissolution methods and the sample aerosols generated by a pneumatic nebulizer are injected into the interior of the high temperature plasma (10000°). The radiation is directed into a multi-channel vacuum spectrometer and the elements determined simultaneously under a single stt of operating conditions. The accuracy and precision achieved in routine analysis are comparable, or superior to those achieved by atomic absorption and X-ray fluorescence spectrometry. - 143 - Analysis of Sorbitan Fatty Acids Esters By HPLC By: N. Garti, E. Wellner, A. Aserin and S. Sarig Casali Institute of Applied Chemistry School of Applied Science and Technology The Hebrew University of Jerusalem Jerusalem, 91904. A need for analysis of food emulsifiers arises at several stages of their production and use, e.g. for production control, for comparison of emulsifiers purchased from differnt suppliers and for the detection of the type of emulsifiers used in a competitor's food product. The litterature reports separation identification and quantitative estimation of the mono-, di- and tri-fatty acid esters of sorbitol and of its anhydrides. Most techniques are based on pretrestment (hydrolysis) of the emulsifiers, derivatization aad use of GLC as the essential quantitative method for analysis. These techniques are tedious, time consuming and not accurate. We propose a new method to separate, identify and analyse the sorbitan esters of fatty acids by HPLC technique. No derivatizatioii is^,necessary. Using U.V. detector, without a need of gradient of eluents and in a short period of time (13 min) mono-, di- and triesters of stearic, palmitic, oleic, lauric, isostearic and sesquioleic acid of several suppliers have been analysed and compared. - 144 - 0 DISTRIBUTED LOCAL AREA NETWORKS FOR CHROHATOGRAPHY LABORATORIES D. Ord and J. Fremajer R & D Division, Spectra Physics, Darmstadt, W. Germany The continuing increased demand for analytical services has lead to major advances in instrument automation,.particularly in the chromato- graphy laboratory. The speed with which analytical data can be generated and therefore the quantity produced has lead to a greater need for laboratory management facilities such as statistical analysis, report correlation and sample tracking. Traditionally, this has been achieved on a larger laboratory computer with the capability to support many instruments and include customized reporting, centralised control and free programmability. However, as with any system based on a centra- lised computer, any failure can have dire effects on the work of the laboratory. With this problem in mind, an alternative approach is presented based on a distributed instrument network. Such an approach provides each station in the chromatography laboratory with independent intelligence and free programmability, but has the benefit of centralised control, remote monitory and the benfitof mini-computers for laboratory management re- quirements. The strategy for inter and tntra instrument communication will be dis- cussed together with its application and impact on the individual chro- matography station and its extension in a local area network. - 145 - 0 RECENT DEVELOPMENT IN HIGH RESOLUTION CHROMATOGRAPHY: ULTRA PERFORMANCE FUSED SILICA CAPILLARY COLUMNS AND LIQUID ON-COLUMN SAMPLING Piet Van Hout Hewlett-Packard Company Hewlett-Packard Strasse 1 7517 Waldbronn 2 West Germany Fused silica capillary columns were for the first time introduced in 1979 at the Hinderlang Capillary Symposium by Hewlett-Packard. Two outstanding characteristics of these columns were immediately recognised. Their flexibility, allowing also unexperienced users to handle the column with virtually no risk of breakage, and, their inherently high inertness due to a well characterized, very pure (less than 1 ppm contaminants) silicum oxide surface. This last phenomenon led to the application of capillary chromatography in areas where, up to then, coventional glass capillary analyses either had failed or only could be carried out with great difficulty. Due to the low surface energy of the pure fused silica a polar liquid phase will not easily form a uniform liquid layer on the surface, which is the reason for the limited availability of phases on fused silica. Recent developments among others crosslinked of the phase, have considerably improved that situation. Crosslinking phases have several additional advantages: it enables the column to be rinsed with solvents in order to remove deposits, it allows the use of more aggressive solvents, and it increases the temperature stability of the column. Hewlett-Packard has developed the technique of deactivating, coating and crosslinking to such a stage, that for certain phases "ultra columns" are in existance which, next to a high chromatographic performance exhibit from column to column retention index variation of less than +-0.5 units and capacity ratio variations of less than +-0.2 units. The technique of introducing a sample directly on the capillary column without prior evaporation will be discussed. This a "Liquid On-Column Injection" offers a number of advantages, wich briefly can be summarized as: - Elimination of sample discrimination because of syringe effects, - Elimination of sample decomposition due to either thermal or catalytic (i.e. metal syringe needle) effects - excellent quantification. During the lecture a dedicated injector will be presented which, in addition to these advantages, can be easily implemented into routine laboratory practice. Characteristics and operational aspects of the system will be discussed and illustrated with application examples. - 146 - 0 DIODE ARRAY TECHNOLOGY APPLICATIONS IN UV/VIS SPECTROPHOTOMETRY AND IN LC/UV DETECTION Daniel Fuster SID Specialist Hewlett-Packard POB-CH 1217 Meyrin 2. Geneva, Switzerland Recent progress in diode array detection, computer control, optical components are discussed. They lead to a new generation of UV/VIS Spectrcphotometers and LC/UV detectors, wich are capable of acquiring, in parallel, all wavelengths of the range, and void the traditional serial access obtained by mechanical scanning. Numerous applications in the pharmaceutical and biomedical fields are presented. By permitting spectra to be measured within a few hundred milliseconds only, this technique makes information much more rapidly available and more readily explotable by such techniques as deconvolution. In addition it allows identification and quantification in many cases where traditional spectrophotometers or detectors are limited by their unsufficient speed. r TEACHING CHEMISTRY - 147 - "Turning Water into Wine": Student Difficulties in Solving Problems J. Dudley Herron Purdue University, Indiana, U.S.A. Abstract The audience will participate by solving a simple problem. Using this problem as an example, Prof. Herron I'ill discuss various difficulties that students encounter in beginning chemistry. J - 148 - 0 THE MODERN LIFE - CHALLENGE AND MOTIVATION FOR STUDYING CHEMISTRY EXAMPLE - NUCLEAR CHEMISTRY I. Maor Department of Education in Technology § Science Technion, Israel Institute of Technology, Haifa. The study of chemistry has lost its "romantic image" and is now consi- dered by most students to be a dull, difficult, illogical and uninteresting subject (1). Modernization of the subject could contribute very much to turn it again into one of the most fascinating subjects studied in high school and later at universities. As an example, a proposal of a new approach to teaching nuclear chemistry is presented. The motivation for the studying of this important subject is obtained by combining the frequent discussion of topics like nuclear energy and weapons by the media with the presentation of some of the most modern research, performed nowadays in the field. As a pre-requisite only a basic knowledge of the periodic table and atomic structure is required. The starting point should be the extension of the periodic table by producing heavier nuclei, thus leading to unstable artificial elements (up to Z =*vlO3). Radioactivity, which may be illustrated as the solution of nature to the instability of nuclei is introduced as a practical instru- ment for atomic age determination, followed by quantitative concepts like half lifetime and isotopes. The shell model and magic numbers should be presented stressing the analogy to the periodic table, leading to new pre- dictions of an additional "stability island" around Z = 114, N = 184, which is now experimentally looked for (2). To show how such elements can be produced, the nuclear accelarator and reactor are introduced. Fission and fusion processes leading to chain reactions which release a huge amount of energy are the basis for the dis- cussion of energy control problems. Finally, both safety considerations and advantages of nuclear energy are discussed in detail. References 1. R.G. Silberman, Journal of Chemical Education, 56, 1036, (1981). 2. G.I. Seaborg, W. Loveland, D.J. Morrisey, Science, 203, 711, (1979). - 149 - 0 nmrnnn nyiynn frta pmm ,TIIN . >nnnn pneia mrm nmrnaii roiyan KB>IJ DISOI mrn - :moa , (m*no»n mawa p!>n m ononw) nmtna nDiya ni!? - : pnunn t>j) ,nnni pnwan - -. pne>on 12 njpn vna , 3 - - :pnwan 11*1*1 An J)7T —•• rai O'OID n O'DID JTJ' ;I7T J71' ti>iirna pnwan - : 60-n nntin pnwa QIU nnnn (4) nou'nn Q>pne»a .(3) ,(2) ,(i) ,nr «jon pnwa niai ,oioKn Dim pnwan .1 nianoa rn»a»3 nnuti mniftm ,>aiii)pi»K vmtwonb *mib pnwan - D'jiim Bitaw >ID Tin o>pne>a Q>Tat>nne» pnwani iriNa .2 "D»iin"n nK *>TD3 iaa o^a^oa .nnunan wiyan oy waa on>at>nn nt pnwa^ .3 o»aiD niDni njan nnt* DnwoKa m^>yani n»aan wiaa na Tin (1) Deutsch and Krauss (1960) "The Effect of Threat on interpersonal bargaining11 in J. of Abnormal and Social Psychology, 1960, 61^ 183 1960, 6^ 218. (2) Boocock and Coleman (1968) "Simulation Games in Learning" Fage Publication, Beverly Hills, California. (3) Tansey and Derick (1969) "Simulation and Gaming in Education" London, Methuem Educational. (4) las*! 113a nNinnn ib-ua nil "n - - 150 - 0 maim ,o>!>E>-?n oiny »"y n^n - ^in nan nannn nwain nnnn n'O'D fiann !>D nnw "nrsnn" nnaaa .nn>n>3 noun" owa KIP^ maynn n ptvonb n - 151 - ,7N'3A *IINI 'ax-ia nn ,'TIN njn .nuim ,y"M7 insm inn .D'yinn nNim7 np7nnn Nian n'33n mn73 'T nn-oi .(i) np'P'sn ny ai7'eu 7Nie"a o-"3'an na'ona mn73 .ininn 70 'p'p7nn njarrti n3inn np7a3i nA*in nae» ,(2) "-minn man" - D"7|7'p»9n ,(3) "mamnn )/H n77iD"»nn" n'33nn 7w nniAona minn naan nainn namin 'n "n paV n'n»3n pa ippn TIN wxin ,nmp'n 70 n'mnnn n7aua mpnnn yinn 'Nivn ai7"»u' .n*n'3n 'NWU 7W anKnn7 D'xmjn 7nmn TIP'H 'AK/IO TIN DA a7i«ma yin nNiina nuVfn N'n rpa'imuj'Nii j\v>xn :(4) D7iya a&yin I\H qj7»n ma m 7 n a'i7n;n73'Nn nf'An 7e» n'ni'iynian .o^a'an na'uni 'iio'n ISDH n'a 7'Aa .(5) n'313'nn nnaDa D'an n'inNna npD3 nwynV IN ,nTa HT D'aiVw DPCD o"j'an na'una yaon 'ym nN nmn7 n"u inj'nan .n'n'3-np'D'Da ni'3Dnn va> n:7a niN'n 7c ii'iynn m'n ay .naaa n"»Ai7T»an rmynap TDa jiNuaDQ D"»'7p'D'an D'yinn va7 D"nn 'yin t*a nu'nnn nvap ,TD7nn 7w 7 11 T-7y nyyann inNTin IE»N ,('"773 ym IN) "yao" Dt»a yixpn yam 'n-'T niipaa niyem np'D'aai n'Ai7i'aa T'n7nn BAOJ 'V nn'Dn 7nn .unuona Ai7Ta 773-ina ,min IHIN ." nipaa RT D'&innn n'n'Dn 'tiii'V .773 mn73 HJ'N n'n'Dnm ny»a ,7133a D'7'An rniua npaAnni mmynn y7na ma"jynnn '3 D'Tyn (6) D'an D'ipnn 'aA7 mil? HIDIIN mjVwn ni'n7 m'iB»y Q"3'an na^un n7nna Q'y7nn nNTin7B imiynn »TN ,na7n -p D^nN DN .137 layn *IN '7INI nai'Vyn na'una 7in'7n na»una yaun 'y70 nNTin IBIN DNH :HNan n7N»n 773a 7 •n 7i73n ia« nsina. itswi fi977-a ^nniy a7E>-ai ipnn niADna np7a3 IT nm3 7n'7y nnponn ,n3i'7yn na'unn lay VN Q"3'an na'unn n7n73n nNima n; a7E»a .'u-'n nm'3a D'7'D7n 1100-3 p7n 1703 law iiPNin ipnnn a7B» 7N*n7n Vy • Q"»7ip'i!>n naiyn Vy 7iny7i ,y7na D'7'n7n 7B» ni3"3ynn 'ninn nsn v'^71 niD37 nnny '317NK» iiiA'm ni3"3ynn inan .n'n*3n 7in'7 '373 Dn'ni37yn D71D nN n'yaipn .ipnn '733 u»nu» 7 in'3 17 Aii'Dnn n3if i3iNa ni y7n mysin D'AiiDn D'7'n7n '3 0'7yn D"UD'DOD D'nin'3 ni'n'3 mysin ,7wn7 ,-\O ."D7'D7p"n n'mnnV y7nn 7y VH nn»n "niaiainn VN nmcnn" n'33nn nN nn7 NVW n7N :7i33 ninn7 ,nniN nn7«> n*7N ;(?n'Ai7i'a ?yao) nnN nt/p'n 7N3 ni'y7nn my3inn 737 n7n'3n n'3'Na 'fipn .nniN nn1? iau» 131N7 DNnna - np'D'sm n'n'3n nN 7n' n'7'nVnE' nyB»a» 13a 'iu'a 'T7 Na (n7Ai7i'ann 7133a) onVmi mm '7ya cmnna np'D'srn ."n'n'3 N7 IN ,yao i37n7" pm'3a A"nDn7 D'ai D'Pi3 ."n'n'a" inmv yixpn7 on"nn7 A1N77 inxn 7y ,in"n pa ,my7axn 7y - 137 laym ,D7737an na7ona yawn 7y7n nNiin niAona Diaa n7n73m 773a H7n73 :DnB»a D7Nl!»137 .i"7Bm ,D77B»n7 ,n773B/ mnnn ,D77in77 T3inn ,mainm ii37nn 7iB»n ,~>znnn ruza ,(a73iiy) ,.3 ,T3iiNi ,.i ,7ay-ia .2 7 7 ni 33n7 T3inn ^rnsnsinn bn nmwrm ,. ,II7PI ,.n ,7TIN ,.3 .TBIIN .3 7 7 ,n"7K»n ,n3pinn 7ID73 mnnn ,y7n*7 inyi ]i3n ,a y7nn nNiin7 np7nnm ,mainm ii3 nn Haggis, S., and Adey, P., "A review of integrated science education worldwide", .*» in New trends in integrated science teaching, Vol. V, 35-39, Paris: Unesco, 1979. Brown, S.A., "A review of the meaning of, and arguments for, integated science", .5 Studies in Science Education, 4, 31-62, 1977. Ormerod, M.B., and Duckworth, F., Pupils attitudes to science, Slough (England): .6 NFFrf, 1975. Lawson, A.E. The development and validation of a classroom test of formal reasoning. Journal of Research in Science Teaching, 1978, L5_, 11-24. Longeot, F. Analyze statistique de trois tests genetiques collectifs. Bulletin de l'Institut National d*Etudes 1965, 2£, 219-237. Tisher, R.P. and Dale, L.G. Understanding in Science Test, Victoria, Australian Council for Educational Research, 1975. I TO: VICE- PRESIDENT, CORPORATE PLANNING/BUSINESS DEVELOPMENT FROM: LEO HEPNER AND CELIA MALE SUBJECT: CAN YOU REALLY AFFORD TO BASE YOUR FERMENTATION BIOTECHNOLOGY/EXPANSION, DIVERSIFICATION AND RESEARCH PROGRAMME ON CONFUSING TRADE STATISTICS AND SENSATIONAL PRESS RELEASES? FOR 12 YEARS WE HAVE MONITORED THE FERMENTATION/BIOTECHNOLOGY AREA i TO DETERMINE PRODUCTION, FERMENTATION CAPACITY, PRICE TRENDS AND FUTURE DEMANDS. WE HAVE RECENTLY COMPLETED SEVERAL SURVEYS ON 'PRODUCT OPPORTUNITIES IN FERMENTATION, 1981-85' I THESE PROVIDE ESSENTIAL INFORMATION FOR PEOPLE LIKE YOURSELF CONCERNED WITH DEVELOPING A CORPORATE STRATEGY FOR THIS AREA. WE HAVE ASSESSED PRODUCTION IN TONNAGE, MARKET SHARES, FERMENTATION CAPACITY OF MAJOR AND MINOR COMPANIES, AND GROWTH PROSPECTS FOR THE FOLLOWING CATEGORIES: 1. ORGANIC ACIDS 2. ANTIBIOTICS (HUMAND AND ANIMAL) 3. ENZYMES 4. POLYSACCHARIDES 5. AMINO ACIDS, (PHARMACEUTICAL, FOOD AND FEED GRADE) 6. VITAMINS, STEROIDS AND ALKALOIDS. i WE HAVE PROFILED THE ACTIVITIES OF OVER 125 COMPANIES INVOLVED IN THESE i PRODUCT SECTORS, WORLDWIDE. WE FEEL THAT THIS SURVEY COULD BE THE MISSING LINK IN YOUR CORPORATE PLANNING AND WILL GLADLY SEND YOU FURTHER INFORMATION. OUR ADDRESS: L. HEPNER AND ASSOCIATES TAVISTOCKHOUSE NORTH TAVISTOCK SQUARE LONDON WC1 ENGLAND TEL: 01-387-2295 i OR CONTACT OUR LOCAL REPRESENTATIVE MR. MARTIN STRAUSS LANDSEAS ISRAEL i TEL: 299-091-2-3-4 i TELEX: 342216 P.O.B. 23011 - TEL-AVIV. i i \ Hewlett-Packard Analytical Instruments Liquid Chromatographs Laboratory Automation Systems Gas Chromatographs Reporting Integrators HEWLETT GC/Mass Spectrometers PACKARD UV/Visible Spectrophotometers Represented by EL.DAIM ELECTRONIC INSTRUMENT CO. LTD. Eldan IS OHQLIAV STREET . JERUSALEM 94467 ISRA6U P.OB. 137C. JERUSALEM 31Q12