ALKIHL. AT ICAT ATm ■ RSAHHAI'TG-A^ISNT OP.. A L IP H A T IC 1 , 4 •••' 3&SAT
DISBSRTATIOH »
Prep.ontnA in P?.rtirtl Fulfillment of the Reculremon t the Dorroo Doctor of Philosophy in the Graduate School of The Chle . State : thilverpity. V ' :A . ;
.t B*A.
The Ohio State University
1953
Approved by ? ^ - A^
TUa aut
ii TABLE OF CONTENTS cont. Page Hydrocarbons from diallylation One step Isolation of 4,4-divinyl-l,6-heptadiene# • 41 Discussion •••••••••••••••• 43 Two step Isolation of 4,4-divinyl-1,6-heptadiene. * 46 Discussion •••••••*•••••••• 47 Experimental and Discussion of 1,4-Hepta- diene Preparation ••••••••••••••• 51 Catalytic reduction of l-hepten-4-yne• * 51 Discussion ••••••••••••••• 53 Chemical reduction of l-hepten-4-yne • • 54 Discussion •••«••••••••••• 55 Hydrocarbons from monomethylation Isolation of 3-methyl-l#4-heptadiene • * • 58 Discussion •••••••••••••••• 60 Hydrocarbons from dimethylation •••••• 61 Discussion •••••••••••••••• 62 ALKYLATION AND REARRANGEMENT. REACTIONS OF 1,4 ENYNES Historical and General »••••»••••• 63 Experimental and Discussion of 1-penten- 4-yne Hydrocarbons from diallylation Ration 2 part halide to 1 part acetylide • 66 Discussion •••••••••••••••• 71 Effect of dilution ••••••«••••• 72 Discussion • •••••*•••«••••• 75
iii TABLE OF CONTENTS cont* Page Effect of temperature •••••*••••• 76 Discussion ••»••••*•••••••• 77 Ratio: 3 part halide to 1 part acetylide • 77 Discussion •••••••••••••••• 78 Reduction by sodium ••••••••••»• 79 Discussion • ••••••••••*•••• oO Absence of sodium amide •••••••••• 86 Discussion •••••••••••••••• 88 Use of lithium acetylide in lieu of sodium acetylide •••••••••«•••••• 89 Discussion •••••••••••••••• 90 Experimental and Discussion of l-Hepten-4-yne» Preparation • ••••••••«•••••• 90 Use of ethylmagnesium chloride • • • • • 90 Discussion •••••••••••*••• 92 Use of ethylmagnesium bromide • •»••• 93 Discussion •••*••••••••••• 9 3 Use of various alkylmagnesium halides • • 97 Discussion ••••••••»•••••• 99 Hydrocarbons from monomethylation Isolation of 3-methyl-l-hepten-4~yne » • • IOI Discussion •••••••••••••••• 108 * Attempted dimethylation •*•••••••• H O Discussion • #•••*•••••••••• 112 IV, ATTEMPTED PREPARATION OF 1,4— PENT ADI YNE Historical and General ••••••••••• 114
lie TABLE OF CONTENTS cont. Page Experimental and Discussion • ••••«••* 118 Preparation • •••••••••*••••« 118 From ethynylmagnesium bromide •••»•• 118 Discussion • ••*••••••*•••• 120 Attempt to prepare ethynylmagnesium bromide • ••••••••••••••• 121 Discussion •••••••••••»••• 124 From 1,4-pentadiyne ••••••*•••• 129 Discussion »••••••»*•••••• 130 From lithium acetylide *•••••••• 131 Discussion 132 V* REACTIONS OF CYCLOPENTADIENE Historical and General *•*••*••••• 134 Experimental and Discussion *••*••••• 137 Preparation •*••••••••*«•••• 137 Attempted preparation of dialkylcyclo- pentadlenyl carblnol • •«••••••»• 137 Attempt to isolate alcoholate • ••••» 137 Discussion • ••••*•»••••••• 138 Attempt to isolate alcohol ••••••• 138 Discussion • *•••••••«••••• 140 Isolation of isopropyleyelopentane • • • 140 Discussion • •*•••••••••*•• 140 Attempted preparation of dialkylcyclo- pentenyl carbinol • ••••••••••• 143 Reduction by sodium and ammonium sulfate* 143 Discussion •••••••*••*••»• 144 Reduction by sodium ••••••••••• 145 Discussion •••••*•••••••*• 146 v TABLE OF CONTENTS cont. Page
Condensation with methyl ethyl ketone • • « • 14-7 Isolation of sec- butylcyclopentane * . . . 147 Discussion ••••*•••••••••«• 148 Condensation with Dibromides •••••••• 148 Trimethylene *•••••••*•••••• 149 Pentamethylene • ••••••••••••• 149 Tetramethylene *1^0 Discussion • *•••••••••••••• 150
SUMMARY ...... 151 INFRARED SPECTROGRAMS...... 157 BIBLIOGRAPHY ...... l6l AUTOBIOGRAPHY
vi INDEX TO FRACTIONATION DIAGRAMS AND MELTIIJG POINT CURVES Figure Page I Redistillation of Higher Boiling Products from 1,4-Pentadiene and Methyl Iodide • • • 20 II Distillation of Products from Methylation of 1#4-Pentadiene by High Dilution Tech nique 30 III Distillation of C-8 fraction (reduced by sodium in liquid ammonia) isolated from allyl chloride and sodium acetylide • ♦ • • 84 IV Distillation of Low Boiling Products from Methylation of l-Hepten-4-yne ••••••• 105 V Distillation of Higher boiling Products from Methylation of l-Hepten«4-yne (re duced in sodium and liquid ammonia) • • • • 107 VI Melting Point Curve of iso-Propylcyclo- pentane •*•••••••••••••••• 141
vii INDEX TO TABLES Table No# Page I Factors influencing the preparation of l-Hepten-4—yne •••••••••*••• 93 II Results of alkylation of 1,4 Unsaturates • 111 III Effects of conditions on yield of Di ha loroagne si urn acetylene •••••••• 1 2 5
TABULATION OF PHYSICAL PROPERTIES
3-Vinyl-1,5-hexadiene • ••••#•••••••« 37 4.4-Divinyl-1,5-hexadiene •••••••••••• 44 1.4-Heptadiene •••••••«••••••••. 52 3-Methyl-l,4-heptadiene • 59 l-Hepten-4— yne #•••••••••••••••# 94 3-Methyl-l-hepten-4-yne • 103
viii INDEX TO PLATES (Infrared Spectrograms)
Plate I page 157 4 , 4-DI VINYL-1, 6-HEPTADIENE (prepared from 1 ,4-pentadiene) 4 # 4-DIVINYL-1 ,6-HEPTADIENE (prepared from 3-vinyl-1,5-hexadiene) 4- ETHYNYL- 4- VINYL-1, 6- HEPTADIENE
Plate II page 158 1 ,4-HEPTADIENE 3-METHYL-1,4-HEPTADIENE 3-METHYL-1-HEPTEN-4-YNE
Plate III page 159 4- ETIIYNYL-4- VIIYL-1, 6- HEPTADI ENE 4- ETHYNYL- 4- VI NYL-1, 6- HEPTADI ENE (twice exposed to sodium and ammonium sulfate in liquid ammonia) 4,4-DIETHYLHEPTANE
Plate IV •••••••••••••••• page 160 1-HEPTEN-4-YNE 3-METHYL-1-HEPTEN-4-YNE 1,4-HEPTADIENE
ix -1-
INTRODTJCTION
The systhesis of* a group of new phenylated olefins wae =t,de possible when Levy and Cope (l) , and later, Rowlands (2), jre able to alkylate allylbenzene in liquid ammonia by first irmiing the sodium salt. The methylene group of allylbenzene j activated b y an adjacent benzene ring and a carbon-to- rbon double bond and contains hydrogen of high enough idlty that amnonolysis of its sodium salt is insignificant n liquid ammonia. This finding suggested the study of kylatlon of activated methylene hydrocarbons of the all- atie series in liquid ammonia, Greenlee (3) and later Levy d Cope (1), reported this type of alkylation, but neither s studied it any further than to determine that such a action was possible. The aliphatic derivatives are more difficult to study 3tn the "true” acetylenic or the aromatic derivatives jause of their greater tendency to rearrange and to poly pi ze, This, in part, perhaps, is the reason their alkyla- m has received very little attention, and, consequently, > meager existing data are in poor agreement* Furthermore, » methylene group can be activated by adjacent oleflnic ups, acetylenic groups, or a combination of them which adens the scope in this field. The possibilities of such a reaction formed the basis of the present study: the isolation, purification, and identification of the products obtained by alkylation In liquid ammonia of 1,4 unsaturated aliphatic hydrocarbons* Fortunately, this work coincided with a need of the American Petroleum Institute Project 45 at the Ohio State * *■ . University. This was a need for engine test studies of a highly unsaturated, nonconjugated, aliphatic hydrocarbon within the gasoline range. Such a hydrocarbon was desired because existing data Indicated that it would have both a high, research octane number and good blending properties* * The hydrocarbon, 4,4-divinyl-1,6- heptadlene, was chosen for this purpose because; (1) it would fulfill the necessary requirements for engine test studies, (2) it would be very unlikely to Isomerize conjugated hydrocarbons when subjected to the temperatures and pressures developed in the manifold, and (3) its synthesis would provide a study of the alkylation (in this case, allylation) of the sodium derivative of an aliphatic 1,4 unsaturated hydrocarbon In liquid ammonia* Since it was necessary to prepare 1,4 dienes in this work, the reduction of 1,4 enynes by sodium In liquid ammonia was studied. Campbell and Eby (4) were the first workers to report that the reduction of dialkyl acetylenes by sodium in liquid ammonia produced quantitately the trans-isomers of the corresponding olefins. Since this method eliminates the experimental precision, aBide from theoretical considerations,
•2 required by catalytic hydrogenation it was hoped that selective reduction of 1,4 enynes to 1,4 dienes could by achieved* If this were successful, then it would provide a useful synthetic procedure for the preparation of 1,4 dienes because 1,4 enynes are relatively easy to synthesize. Another important phase of this work was an attempt to condense the sodium derivative of cyclopentadiene in liquid ammonia with a ketone to prepare the corresponding alcohol, commonly referred to as fulvanols. It is well known that cyclopentadiene, an unusual 1,4 diene containing an activated methylene group, can be condensed with ketones in alcoholic solvents under basic conditions; however, the fulvanol are dehydrated spontaneously to produce fulvenes. In addition to the preparation of fulvanols, it was desired to reduce the fulvanols to alkylcyclopentyl or alkylcyclopentenyl carbinols In order to develop a new method of synthesis for cyclopentane derivatives. The complexity of these studies led to many problems upon tfhich there is no information in the literature. These, though far afield from the main objective of this work, were considered pertinent enough to receive considerable experimental attention and to be reported fully herein. TECHNIQUES a k d definitions A* Synthetic Apparatus
Grignard reactions Involving no more than 3 liters or reaction material were run in a 5-liter, 3 -neck glass flask equipped with a Hershberg stirrer, water-cooled glass condenser and addition funnel. The preparation of acetylenic Grignard reagents required a slight modification of the apparatus described above, because It was necessary to apply approximately 0.5 atm. of pressure. An air-tight seal about the stirrer shaft was accomplished by attaching the shaft to the stem of a male ground glass ball Joint which turned inside a female Joint. Exter nal pressure was applied to the fitting through an open face ball-bearing. The open end of the water- cooled condenser was connected to a mercury manometer, which also served as pressure relief device. Excess pressure was released manually through a capillary tube connected to a Dry Ice-cooled trap at atmospheric pressure. Larger scale Grignard reactions were run in a 5 gallon copper-lined reactor fully enclosed In a Jacket suitable for heating or cooling by the circula tion of water or steam. A multiple-blade propeller shaft-type stirrer was driven by a ■£ H. P. motor. This reactor and the water-cooled copper reflux condenser have been described in detail by Boord, Kenne, Greenlee, Perllsteln and Derfer(5)« The preparation of allylic and propargylic Grignard reagents were run In a special cyclic Grignard reactor described in detail by Boord, Greenlee, and Rowlands (6), This reactor consisted of a 3-liter boiling flask, a A X 104 cm glass reaction chamber enclosed In a full length water-cooled Jacket, and a water- cooled copper condenser of the type described above* The use of cyclic Grignard reactor represents an Improvement on the high dilution technique (7) which Is commonly used In preparing the Grignard reagents of halides that will self-condense readily; In the cyclic apparatus the Grignard reagent is removed from the reaction zone as soon as it is formed, and the concen tration of Grignard reagent that can come in contact with the unsaturated halide is reduced to a minimum* All reactions in the solvent liquid ammonia were carried out in a 3 or 4-neck flask of suitable size, equipped with a Hershberg stirrer and Dry Ice-cooled condenser as described in detail by Henne and Greenlee (8)* This condenser consisted of Inch block tin tubing colled into an ascending spiral which was fitted into a double walled Jacket,the annular space of which was instilated with sllica-gel and asbestos* The majority of the reactions were carried out at the
m t reflux temperature of ammonia (-34°), the reaction flash was almost entirely surrounded by asbestos fiber in order to minimize any heat transfer. In the reactions carried out at temperatures below the boiling; temperature of ammonia, direct external cooling was provided to the flask by means of a Dry Ice-acetone slurry. Catalytic hydrogenations were carried out in con ventional American Instrument Company rocker-tvpe autoclaves or a modified Burgess-Farr apparatus. The latter was equipped with a double walled metal reaction cell which could be heated or cooled by circulating water*
Fhyci cai Ion at antr . Qrv^ 5- ^ a tpor a
The boiling points listed in tables of physical constants irere determined in a modified Cottrell type (1 0 ) apparatus at a constant nitrogen pressure of 760 mm, which was maintained by electronic manostat. The temperatures were measured by a platinum resistance thermometer, calibrated at the United States Bureau of Standards, in connection with a Leeds-Northrup Mueller bridge. The boiling points are given to the second decimal with a probable accuracy of 3:0,04° C* The boiling points listed at pressures less than 760 mm, are vapor phase equilibrium temperatures which were measured by the same method as described
- 6- previously. The boiling points reoort-.:d elBG’.rhere, herein vrero determined by commercial mercury-ln-rlaES thermometers which were calibrated against the plati num re mi stenco tbermometor. The boiling nointr so det ermined , but corrected for atmospheric pressure devia tion, were employed to plot the rectification diagrams A Valentine Precision Refractoneter, manufactured by the Industro-Scientific Instrument Como-my, con- nectod to an electronically controlled constant temper ature (20°CL) inter bath tb.c used to measure the refrac tivo indices to an accuracy of 0 . 0 0 0 1 . The densitie determined by use of either 5ml or 20ml pycnonieters which uere calibrated with iso octane and benzene. The electronically controlled water bath used for such measurementc was maintained at 20°C.ll0.02°C* The densities so obtained were accurate totO.OOOl gja/rnl# The methods and equations derived by Rossini and co-worhers (11,12,13,14) were employed to calculate
the ouritv- « . of hydrocarbons% d from their respective freezing and melting curves. The equation -In (l-lTg)® -InH^ A(t£0-t (tQ-tf)J gives the relationship of these terms, which a.re defined below, and furthermore the relationship between the temperature of equilibrium and the -7- composition of the liquid •ph.” ce, This equation is true dor* sufficiently dilute solutions in \rhich the impurities dorm an Ideal solution vrith the solvent and are insoluble in the solid phase. XT^«-!-Iole fraction of the major component.
ITo* (1-1^) * Sum of the mole fractions of other components.
t-f » Observed freezing point in decrees centiara.de
dor the pi von hydro c ar’oon.
tf0 » Freer,iny uoint dor zero impurity or vhen IT2»0.
A ■= First or main cryoscopic constant in deq. 2 vrhere A is do fined as H°m/FTp0 .
B * Secondary cryoscopic constant, in do p. ^ vhoro B is defined as l/Tf0 -(ACp/2 H°m) •
*ro- R*2t*o i n q o o 2 - l. f o 1 ero I.,.* our*i o^ 1 n 1.0 ^ absolute.
/\H°m * The heat of fusion / mole. Co * The heat capacity per moleat constant pressure.
R® The gas constant per mole (R m 1.98718 cal/deg. mole).
- 8 The equation above Is put In the following form; logio Purity * 2.00000 - (A/2.30259)(tfQ-tf) (t-fo -tf)j for tlie calculation of purity. In most cases, the term B Is small enough that It may be neg lected. Thus, the purity equation may be written -ln(l-l?2)« A(tf0-1$ * Since -ln(l-ITg) may be ex- 2 3 pressed as I!2*.l/2N2 1/3^2 with the higher terms Insignificant In very dilute solutions, the equation may be written as ITg * A(tf0-t-f) . Thus, it is a good approximation that the mole fraction of Impurity Is directly proportional to the freezing point lowering# The purities of the compounds for which no cryo scopic constants are available were determined by essentially the same method as that described by Rossini and co-workers (13). ifo* theoretical freezing point of 100fa pure material (15) , was deter mined from the time-temperature freezing curve by mak ing the simplifying assumption that at ta., the mid point temperature, the concentration of impurity pre sent in the liquid phase has been doubled, and that the difference In temperature between the observed freezing point andhti Is equal to that temperature by which the to is depressed below tf, thuB tG ■■ tf^(tf-tJ-X However, this is true only If the freezing curve Is rectilinear to the mid-point time, if the rate of crystallization is constant, and If the Impurities all remain in the liquid phase.-9— II. ALKYLATION AND REARRANGEMENT REACTIONS OF 1,4 DIENE3
A. Historical and General
Active methylene compounds of the aliphatic series have received very little attention with the exception of cyclopentadiene, i.e., 1,3-cyclo- pentadiene, which has been described as ”The indene of the isocyclic series” (17)* Cyclopentadiene is anomalous among the 1,4 dienes because the double bonds are conjugated and it exhibits the properties of an allcyclic conjugated diene. It adds bromine 1,4 (17) (18), as well aB hydrogen chloride (19) at low temperatures, forms and adduct with raaleic anhydride (20), and undergoes facile, reversible dimerization to dicyclopentadiene (21), (22) ana logous to that of butadiene to 4-vlnylcyclohexene. In spite of its properties as a conjugated alicyclic diene, cyclopentadiene possesses an active methylene group; its structure is comparable to that of indene and fluorene In the condensed ring systems. Thiele (23) compared the reactivity of the methylene group in cyclopentadiene with that of the -methylenic group in ketones and later (24) he reacted cyclopentadiene in benzene with potassium to form the organometallic derivative. The cyelo- pentadlenylpotassium was reacted with carbon dioxide
-10 to produce a dimer of cyclopentadiene-carboxylic acid* He also prepared fulvenes by condensing this potassium salt with ketones. Later, Alder and Holzrichter (25) alkylated the salt with various alkyl halides and benzyl chloride. They proved that the resulting benzylated product was not the expected 5-benzylcyclopentadiene, but principally 1-benzyl and 2 -benzyl compounds. Grignard and Courtot (26) (27) reacted cyclo pentadiene with ethylmagnesium bromide by a meta- thetical reaction to prepare cyclopentadienyl mono magnesium bromide. The later when reacted with ketones produced fulvanols. Greenlee (3) Introduced the use of liquid ammonia aB a medium for reactions of cyclopentadiene. He metalated the hydrocarbon with sodium amide and alkylated the resulting cyclopentadienylsodium with aLkyl bromides and sulfates. He found 2-ethylcyelo- pentadiene as the main product end a smaller yield of the 1 -ethyl isomer which confirmed that found by Alder and Holzrichter. At 34° the polymerization of cyclopentadiene was reduced to a small degree, there by eliminating the necessity of liberating the monomer from the resulting liquid dimerization products as obtained by the other workers. Further evidence of the anomalous behavior
-11- of cyclopentadiene among the 1,4 dienes Is shown by the fact that reduction by sodium In liquid ammonia is similar to the reduction of l-alliynes (28), that is, one-third of the hydrocarbon is reduced and the remaining two-thirds formed the salt. In contrast, 1,4-cyclohexadiene reacts very slowly, If at all, with sodium and Is not reduced by nascent hydrogen* Thus, cyclopentadiene possesses a very reactive methylene group because Of Its 1,4 diene character istics, but at the same time exhibits properties of a 1,3 conjugated diene* Cyclopentadiene would be expected to possess more acidic hydrogen than any of the allcylic 1,4 dienes because of resonance staHLization of the anion which Is completely symmetrical* On the other hand, Taylor and Connor (44) showed that the methy lene group of 1,4-pentadiene could be metalated by sodium amide in liquid ammonia* Upon carbonation of the 1,4-pentadIenyl sodium in an Inert hydrocarbon solvent and subsequent hydrogenation of the resulting acid, they obtained exclusively diethyl acetic acid. Paul and Tschelitcheff (15) found that 1,4-pentadiene reacted very slowly with an alkyl Gri^iard reagent at the boiling point of ether and failed to liberate hydrogen when treated with alkali metals. They pre pared the organometallic derivative successfully by
-12- re r.ctlng X , 4 - p ant '-.dier-e wi th phenylpo t. a s r; i i .m
f r i: cnaen^J v W r. *o ■',■■. h t -' ;. r 1'' tivs, wh©n c rbonated, gave 3,5 -pentadienolc acid* Y/Iien plperylen© was reacted with phenylpotasslum In benzene, they obtained only high molecular* we 10111. ac Ids upon c arbonat 1 on• They al s o r©ac ted the potassium derivative of 1,4-pentadiene with, allyl chio ride and up on hydrogena tion of the re sult ing octatriene claimed that n-octane was formed exclusively* Since piperylene polymerised under the reaction conditions in the presence of phenyl- potassium, the isolation of only the straight chain isomer must be explained by rearrangement of the original 1,4-pentadienyl anion to the more thermodynamically stable 1,3 conjugated isomer* 1*1 quid ammonia was proposed as the reaction medium for 1,4 dienes by Greenlee from his explora tory work with 1,4 enynes* He presumed that alkyla— tion would occur exclusively at the secondary position* This would appear to be a logical Inference providing that the rate of rearrangement in liquid ammonia was much slower than the rate of alkylation* To the extent that rearrangement did occur, the sodium addition compound was expected to obey the “benzohydryl rule” as postulated by Wooster and co-workers (16) (29) (30), and be spontaneously
- 1 3 - ammonolyzed. The "bensohydryl rule” states that in ammonia at its boiling point, the sodium or* potassium addition compound of hydrocarbons v/hlch are reduced by sodium in liquid ammonia are ammonolyzed except when the metal is present in the benaohydryl grouping as (CgH^JoCI-I- • Wooster and Ryan (16) themselves pointed out an exception to their rule, but it is applicable in most cases, Allylbenzene was alkylated exclusively in the secondary position (l) (2), which indicated the double bond was also effective in stabilizing the anion* However, some rearrangement did occur in this system since propenylbenzene was one of the reaction products isolated by Rowlands, Rearrangement was expected to be one of the major adverse factors in the present research, be cause Birch (31) v/as able to reduce 4 -phenyl-1 -butene to phenylbutane by digesting the phenylated olefin with sodium in ammonia for five hours* Birch also determined that potassium amide in liquid ammonia would cause migration of the nonconjugated double bond in 4-phenyl-1—butane to yield 4-phenyl-2—butene and polymer after stirring for six hours in liquid ammonia solvent* Xn the aliphatic series he rearranged 2,5-dimethyl-1, 5-hexadlene to the con jugated 2,4 diene with both sodium and potassium amide* The latter was somewhat more effective be cause of greater solubility* 3. Pbcoerimental and Discussion of 1.4-Pentadlene. 1. Pi’eparatlon 1,4-pentadiene was prersared 1:>y the deacety- .atlon of 1,5~pentanediacetoxy nentane (9)* To iomraerclal 1,5 pentanediol (duPont) (722 y, , 7*0 m. , rhich v/as preheated -to 150°C) , acetic anhydride 15^5 y. , 15* 34m.) was added dropwdse over* a r?er- od of* one at such, a r-.te as t o ~lve a subeti’jctlnl ■eflm:. The reaction mixture was reflu;:ed for an ddltional two hours after which it, was stripped of xcer.s acetic anhydride and acetic acid. The residue, rude diacstatG, w*<.s vacuum distilled (5 theoretical late efficiency) whi ch 1905 r;, (”b . p, 12 8°C/20n?3 , a? 1.4372) or a yield of 91. 5, j based on the diol. The di acetate (12C3 c* , 6.4m.) w s paerolysed a nasslnr it throudi a vertical h e o r class conbus- ion tube (2,2 X ICO cm) packed with cracked Pyrex £172) £*1 ass. The temperature was maintained as Lose to 575°C*Jl50 as possible while the diacetate \& added at a rate of 4-5 drops/sec. (300 - 400 :,/hr.) . Some very low—'boillns material was rolved duriny the oyrolysis which was not con- >n sod by a Dry Ice-cooled trap. The pyrolysis liquor was stripped of 1,4- tntadiene at about two plates efficiency to yield
—15 ~ 2 7 5 g. of crude product- (2 5 . 0 — 26.5°) amounting to 63 *2,?£ deacetylation Tor the first pass* Tlie residual pyrolysis liquor was washed with, ice- water (until essentially Tree of acetic acid), dilute sodium "bicarbonate solution, and ice—water the crude was clarified by shaking with lsl glycerin—water mixture and dried by percolation through anhydrous sodium sulfate. The crude 34-4 g. on fractionation gave 169 g* (b.p. , 148O 5 n 2 d 0 1.4157) of 5-acetoxy-1-pentene and 155 g. of unchanged dlacetate. The amount of the ’'monoacetate1’ represents a yield of 36.7/£ based on the diacetate. This material was recycled through the pyrolysis tube at about 525°C to produce an additional 107 g. of
crude material or a conversion of 7 2 * 0 % in the second pass. The crude 1,4-pentadiene was compos ited giving a total of 382 g., which represents an 80.2^ yield based on the dlol or an 87-5^ yield from the diacetate. A larger run was made follow ing the same procedure except that the residual pyrolysis liquor from the first pass was stripped only to 148° » and recycled as such. The yield from the second pass was lower (62^), but the time saved more than compensated for the poorer yield. The crude 1,4-pentadiene fractions were bulked and dried by percolation through sodium sulfate.
- 1 6 - 'ii r Tnp.toriP.l ( 1 0 7 5 on rlir:tlll'‘.tinn (1:5 -20
"I ' r) r^.ve 74-9 C (69 * 7'6) o ± ^ o o d ■■■>rod,.,.ct °.nd 31 c* (12.0;') o f r e d 1 s t i 11" bl e ^ . Tlie plun r i c nX r*oocrtios nr*c- ivon ’oo 1.o\r.
PIt ^ s I c q I P r o p e r t i e s of* 1,.6 - P on *t> O-Cx. 3.9iis .
T n l s ;;orl: T.d t,oT,"."t'n no (33) P* * C - 1 4 1 . 0 1 - 1 4 7 . 9 1 • ) :rjn 2 6. XO 9 6 . 0 9
% ° O • 66 0 A 0 . 6 6 0 7 20 & 1.9326 J. «0 o
1 7 - 2. Hydro carbons from Monomet.liylat.ion of 1, 4-Pentadiene.
Experiment 1. Uncontrolled. Methvlatlon
One mole of sodium amide was prepared from sodium (2 3 . 0 g, 1 gram atom) and 500 cc, of liquid ammonia containing ferric chloride (0.3 e) (8). As soon as tlie evolution of Hydrogen had ceased, l»4-pentadiene (68.2 g, 1.0 m) was added as rapidly as the capacity of the reflux condenser would allow. The formation of a salt, red in color, was instan taneous and relatively exothermic. Methyl bromide (95.0 g; 1*0 m) was introduced into and under the surface of the reaction mixture over a period of 45 minutes. The reaction mixture was stirred for an additional 30 minutes, then hydrolysed with ammonium chloride and water. The organic layer was separated mechanically, washed with water, sulfuric acid, di lute sodium bicarbonate solution, and dried through anhydrous sodium sulfate. An oily layer, which was not steam distillable, adhered to the walls of the flask. The small amount of hydrocarbon which remained at the interface of the organic and aqueous phases during mechanical separation was polymeric in nature. The recovered material, 7 1 . 0 g (87.8^0, was distilled at about 12 plate efficiency, to give t3-P©ntadiene (8.0 g* bun.'>43.0: - 46*2°C, 20 ■■ A ' d X.4291 —. X.427S) and a mixture (29. 8 grans, ? .3°C - 74:.80C, n^P X.4X7X - X . 44X3} m e ... in :;aXX ■ proli-abXXIXy..'■ cons5. rte d; 'of .c1 si and ' 1 -methyl -i,3—phnhadien© xnd ithS'. e?:pected dimethylr ^oa -nnodnet:,:: 3 »3^dto^xli3dl^X^.4«p©n1>d X Xlxe noXyiner*. XX ' was pnineipally a .■ "■ : : ’ :v.?i'-:- >cause X^xe . xaa JoniXy; of : It,.'; di stilled at r - ‘ -X75°C - ', . ' 3; •": >7 • ■Vi h . * 2 t^P . X,* 4 5 6 3 ; — ... X . 4 7 3 0 ) * : Hir021 -tlionnla tlie materl m % ;. t the platec-v. was rodistilled at about 20 plates ■ S ' i i P ■ficiency, It was notposslbXo to separate or to ib::y;pis .entifj’ .any pure' compounds, , The mixture boilinr in the 70 * s was combined th P. lire material from 4 other nuns and hydro- rated at 8 0 ° 0 over 5/£ of its weight of U.O.Ih - ckel (Xfnivensal OIX Products Company* s nichel- -Iceleel gu h r ■ catalyst) . to■. give a mixture . of -:hydro*: rbons (n^P 1 . 3 8 4 0 ) • After* treatment with, aqueous tassium perm an gen ate fox* four hours at room 1 . 1':' mperature, to remove any residue oleflnio msteriai 9*0 /grams: .waelddstilled; .ai>.'X|5r0© .. plates ■; efficiency,.!■■' juf«Sel ■ . ■ ■ ■ . . : > ' ’•. ’1 . '", : c '.'■P* -, ; ■ v ''V e1i V . f 'f t X i g nhmheito ;';;3-':bdrtS:' > 7..' .:. ; - ■«.“ '•*...* *• -s ; ; - gVjt£-7;4' ■'■■'■ ' • a . V > . r y !-r. i r : ; ^ v ^ + V REDISTIUATION OF HIGHER BOILING PRODUCTS RESIDUE FROM 1,4-PENTADIENE ANO METHYL IODIDE 1.4500 1.4450 trow CHj-CH^C-CH^CHg 1.4400 1.4350 L4300 1.4250 1.4200 14150 % CHARGE DISTILLED T3,*<^> ** -^-*.T? fc»—" A A *?TPT1 «- >4 ^ * *■ ^ ^ 4 - * vau j m * -* k ‘ m'> ^ -J 1 * * A- *L *k^’ A * n? ^ •♦"T^mTTr' » ^ « f ^ ^ l ^ i •, 3 -^le thriven! riie T his ~.Torli L ite r* rvb lire f 6?) F.~. (m.p.) C r"i. ri c n '•'I1' cs ■ 3.^.°C /760 r.m 62*30 6 2 .2 3 , 20 - 4 0 .6 6 4 3 0 .6 6 4 0 20 n d 1 .3 7 7 0 1.3768 3,3 -Dim ethylpentr.rie T h l s T,;o rh L ite rature f 85) F.p.(m .p.) C - 1 3 5 . 6 1 - 1 3 4 . 9 8 3.p.°C/760 nm 86.07 8 6 .0 5 0 .6 9 4 2 0 .6 9 3 3 20 n d 1 .3 9 1 1 1 .3 9 1 0 -21- Discussiont The conditions for the uncontrolled methyl- atlon of 1,4-pentadiene were especially conducive to rearrangement. None of the starting material was re covered, but some had rearranged to 1,3-pentadlene. This was expected because it was known that 1,4 dienyls could be rearranged to their conjugated isomers by sodium amide in liquid ammonia. The hydrogenated products, 3 -methyl- rontane and 3 ,3-dimethylpentane, proved the carbon skeletons of the alkylated products, and gave some indica tion of the ratio of mono- to dl-alkylation. Since approximately 45?> of the material polymerized during the reaction or in distillation, any attempt to predict the exact nature of the reaction and relative yield of pro ducts was considered unwise. In all probability, the ap parent ratio of mono- to dl-alkylation is (8.5 to 3 molar ratio) because 3 -methyl-1,3-pentndione formad by roarranre in ert of monoalkylated product, is more prone to polymer ia ation than 3*3-dimethyl-1,4-pentadiene. Furthermore, it was judged impossible to separate, by distillation, these mono- and di-alkylation prodticts, even if the conjugated monomethylated products were reduced by sodium in liquid ammonia to the mono-olefin, because cis-3-methyl-2-pentene (h.p. >?0.44°C) and the trans isomer (b.p. , 67.70°C) boil in the range predicted for 3*3“dimethyl-l,4-pentadiene (b*p., c c - 71 cj . Any physical property evaluation of the plateau material has the same limitation as that of the -22 comparison of the hydrogenated material. The absence of any n-hexane is indicative that the aethylation of 1,4-pentadiene led exclusively to substitu tion in the secondary position. This is in agreement with the results found by Levy and Cope (l) that allylation of allylbenzene occurred only in the secondary position, Paul and Tchelitcheff (15) reported that the sodium deriva tive of 1,4-pentadiene in benzene on carbonation gave an 86;* yield of 3 >5 pentadlenoic acid. They also reported that hydrogenation of the triene resulting from allylation gave, exclusively, n-octane. However, this writer submits for inspection their reported physical properties along with the accepted values for n-octane and 3-©thylhexane. Physical Property Comparison of Octanes Paul and n-octane (33) 3 -ethvlhoxane (83) Tchelitcheff F.p (m.p.)°C -56.9 glass --- B.p °C/760 mm 125.6 ' 118.7 125 d^P 0.7024 0.7128 0.709 1.3976 1.4021 1.4003 The most probable impurity in their n-octane was 3-ethyIhexane which resulted from the non-rearranged sodium derivative, Unfortunately, precise reaction conditions were not reported, but it is doubtful that rearrangement occurred exclusively. -23- The lower reaction temperature in liquid ammonia (-34°) undoubtedly helps to control rearrangement* Fortunately, to the extent that rearrangement does occur, * the newly formed sodium derivative is ammonolyzed because the solvent is more acidic than the conjugate acid of the base. This is evident because no alkyiation occurred on the terminal position* Ibcnerlment 2: Simultaneous Addition of Diene and Kethvl Iodide. To one mole of sodium amide in 500 cc. of liquid ammonia was added 1,4-pentadiene (68.0 g, 1.0 m), thoroughly mixed with methyl iodide (142.Og, 1.0 m), over a period of eight minutes, or as rapidly as the reflux condenser would permit. As soon as the addition was finished quenching of the reaction was carried out rapidly with ammonium chloride and completed with water. The organic product (68 g or 83*0# based on the theoretical, yield of 3-methyl-1,3“ pentadiene) was separated as usual; however, the wash water had a strong amine odor. The reaction mixture was distilled on a column capable of 20 theoretical plates to give one definite flat (25^) of unreacted o p0 1,4-pentadiene(b.p.,25-26 C; n 3 ,1.3880 - 1 .3 8 9 0 ) and a plateau (21.0 g, 31.0j£) (b.p. ,69.5 " 74.8°C;n^P which consisted of 3“methyl-l,3-pentadienes &nd 3,3-dimethyl-1,4-pentadiene. The residue (10.2 g, - 2 4 - 14,55) was polymeric material and was discarded. Discussion: Tlie conditions utilized in this experiment were designed to eliminate the formation of the conjugated Isomers by reducing the time for rearrangement* Methyl Iodide was used in lieu of methyl bromide because of the iodide*s greater reactivity and because the Iodide, being a liquid at room temperature, could readily be mixed with the diene* The Isolation of the unreacted 1,4-pentadiene and formation of methyl amine indicated mixing of reactants was not suitable because it did not assure formation of the dienyl salt* Only a very small amount of 1,3-pentadiene was formed, but the ratio of dialkylation to conjugated monoalkylation was not changed appreciably from the first experiment as Judged by the observed boiling point spread and the refractive Indiess of the fractions* Sxneriment 3 - Simultaneous Addition of salt and methyl Iodide The sodium derivative of 1,4-pentadiene (68*0 g, 1,0 mole) was prepared from one mole of sodium amide in 500 cc, of liquid ammonia, and at the same time, 500 cc* of ammonia was liquefied in another 2-liter, 4-neck flask* By means of ammonia tank pressure, the contents of the first flask were added to the second flask, simultaneously with the addition of methyl Iodide, over a period of 12 minutes* The - 2 5 - nothy! iodide addition rate was controlled to mlntain a sllyht red color idicatiny the pre sence of the 1,4-pentadien3tL salt* The reaction mixture was quenched imrnodlcutely with a saturated solution of ammonium chloride. The use of aqueous ammonium chloride facilitated the separa tion of layers; use of dry ammonium chloride often 1 ei to formation of emul sions, ecpoci lly when any amino was presort. The o r rrv.nl c material was separated in e c h ?,n i c al 1 y, and was \n- shed and dried as usual. The recovered material (76 y. 92.2,6) was fr*‘ctionod at 15-20 olate efficiency to ~ive v i — - ly^-.pentadiena (6.0 r, b.n. , 43.0-46.0; n^P 1.4297- 1.4265) t 23 c mixture (b.p., 69.7 - 75.0°C; n^P , 1.417-3 - 1.4462) which was similar to the previous experiments, and 3-methyl-1,4-pentad!one (12.2 yrams, b.p., 43.8 - 51.0°C, n?P 1.4001 - 1.3932). The latter was combined with like nr ter- ial from a 1 error run, (in which the sane procedure arcs followed hut the yield was only 9,6) and redis tilled to yive 23.9 C (54.3d of the charpe) of rood 3 -methyl-1,4-pentadiene(b.p., 49.2 - 49.4°C» n^P , 1.397S - 1.3980)* A heart cut was taken for the physical properties listed below: -26 3 -Methy1-1.4-pentadlene This work Literature B.p.°C/76C mm 49..62 49.0 - 49.5 20 d 4 0.6821 ----- n IP 1.3980 1.3981 - 1.3984 The 3-methyl-1,4-pentadiene was hydrogenated at 80°C. over its weight of U.O.P.nickel. The hydrogenated material . (n^P,1.3842)vas stirred four hours with acueoue potassium permanganate at room temperature, and then distilled at 15-20 plates efficiency to give J> -methyl pent an e in 71/» yield. Its physical properties (b.r. ,62.31 *C/760mn,n‘¥l.3770. d^0.6642) compared very favorably with the accepted values for 3~methylpentane (see page 21 ) Dir:cuscion: '-my hydrocarbons that might be produced by hydrogenation of the reaction products obtained in this experiment hove all been synthesized in high purity, and their physical properties are considered of more value in proof of structure than an elemental analysis, in as much as the latter would not distinguish between structural isomers. The very good comparison of physical properties leaves little doubt as to the carbon skeleton. (Unfortunately, 3-methyl- pentane has never been known to crystallize, so cryoseopie proof of Identity and purity of this product could not be obtained). -2 7 - The dio3.ef ins noesiblo In s.. Imovm c-^roor. e’coleton of 5 -methyl per tare a no either cunul "ted, conjugated, or* non- ocr hwat'-d, thir rabec the! r identities single to prove rirco the physical properties of the re hydrocarbons are well hnoam or can bo accurately predicted. Fo s s ibl e 3 -Me thy loon t ad i ones 3.F.°C d*!;? Reference 3-methyl-1,4-pentadlere 4p.62 0.6821 1.3980 This worh 3-methyl-1,2-pentadiene 7 0 . 0 0.713 1.425 (82) 3-aethyl-l,3-nentadiene 76*0 0.719 1.446 (82) The most significant achievement in this experiment was the isolation of 3 -methyl-1, 4-ner. tadiere. The yield was relatively low, but could ha.ve been Increased, probably, if the reaction time were shorter. The salt in solution was transferred as fast as possible with the existing apparatus, out even then, the reaction time was too long. Rearrangement of the monoallcylated product was still a very predominant reaction; this made it ver^r difficult to isolate the dimethyl rated product. The actual amount of the dinethylat,ed product was not proved but was estimated from physical property comparison of previous experiments to be approximately 5-7^ of theory. -28- Experiment 4: Hlvh Dilution and Short Reaction Time To one mole of sodium amide In four liters of liquid ammonia in a 12-11ter flask was added 1,4- pentadiene (75.0 g, 1.1 m). A b soon as the reaction subsided, methyl iodide (142.0 g, 1.0 m) was added in two minutes by means of a pressure equalizing separatory funnel. The rea.ction was quenched im mediately with ammonium chloride, followed by water. This procedure made the recovery of products v»ry difficult because of the volume of water necessary to dilute the ammonia. In subsequent runs of high dilution, it was found advantageous to add only enough water to make the organic material form a separate layer, and then to siphon the "hot" ammonia solution Into a large volume of water. It also helped In the recovery of products to add n-pentane as solvent, which was added after the reaction was quenched but before the addition of any water. By use of this procedure for recovery of material, it was possible to obtain 74 g (91^) of crude (n^P1.4304} which was fractionated at 15-20 plates efficiency to yield 1,3-pentadiene (4.5 6* 3-methyl-1,4-pentadiene (16.2 g, 22^; b.p., 49.4° - 49.6°C; n^P, 1.3971 - 1.3982) and the mixture of con jugated monomethylated and dimethylated products (28.1 g, 38 b.p., 69.5 - 76.0, n ^ , 1.4206 - 1.4428). -29- RESIDUE distillation of products from m e t h y u t io n OF 1,4 - PENTADIENE BY HIGH DILUTION TECHNIQUE L4400 1.4350 6 C 1.4300 FIGURE II I V - 4150 L4IOO 50 m 9 * 'If * 1.4050 CHj^CH-C-CH^CHj CH9 14000 The amount of dimethylatIon was probably decreased, but this was not apparent from the distillation curve* Discussion: The optimum conditions found for monomethylation of 1,4-pentadiene in liquid ammonia are: (1) normal addition of the alkylating reagent to the sodium salt; (2) slight excess of the diene; (3) high dilution; (4) very short reaction time. Under these conditions, the best yield of 3-methyl-1,4-pentadiene was 21't, which indicates that this aliphatic diene is much less stable than its aromatic ana logue, 3 -Phenyl-3-methyl-1-butene. Monomethylation of 1,4-pentadiene is not a "clean" reaction and is critically dependent upon reaction conditions, but it does provide a new method for preparing 3-methy1-1,4- alkadienes. It would be difficult to adopt this preparation for large scale operation because of the large volume of liquid ammonia and the violence of the reaction; however, it is suitable for small scale laboratory experiments. Further more, it illustrates that the rate of rearrangement in liquid ammonia 1b slow enough to allow raethylation In the secondary position, whereas Paul and Tchelitcheff apparently got chiefly primary alkylation in benzene. -31- Hydrocarbons from dimethylatIon of 1,4-pentadiene Experiment li Simultaneous Addition of Diene and Halide. Sodium amide (2 moles) was prepared in one liter of liquid ammonia, as usual, in a 5-liter, 4-neck flask. 1,4-pentadiene (68.1 g, 1.0 m) was added simultaneously with methyl Iodide (284.0 g, 2.0 m) over a period of 14 minutes. The addition of the methyl Iodide was regulated to keep a slight red color; how- ever, the color disappeared after approximately 60^£ of the methyl Iodide had been added. The remainder of the alkylating reagent was added rapidly, and the reaction was quenched with am .onium chloride followed by dilution with water. The organic material was separated mechani cally, washed, and dried. The recovered material (75.0 g, 78#1;£) was distilled at 15-20 plates efficiency o to give 37*6 g (50.1>£) as a plateau (b.p. 69.5 C - 76.S°C, n^P 1.4316). This material was hydrogenated over 6% its weight of U.O.P. nickel catalyst at 80°C. The hydrogenate, after treatment with aqueous potassium permanganate, yielded on distillation 3-methylpentane, 7 parts (27.4 grams) and 3*3-dimethylpentane, 3 parte (12.2 grams). This represents a yield of 12.8/£ (based on theory) of the dimethyl&ted product. The molar ratio of mono-to di-alkylatlon products obtained in dialkyla- tion was 3=1 whereas monomethylation gave 2.8:1, Discussion: The yield of the dimethylated product was not much better than that obtained in uncontrolled mono- methylatlon. Even though a second mole of methyl iodide was used; the sodium amide concentration was evidently great emough to cause rearrangement at a rate approaching that of methylation. This indicated that the reaction time was too long, but in order to shorten the addition period, the problem of controlling the reaction became a major factor, A run at -70° was carried out on a 0,5 mole scale in two liters of ammonia, but the ratio of products was not sig nificantly altered as Judged from its distillation curve. The carbon skeleton and approximate ratio of the chief products were proved by hydrogenation of the mixture, thereby giving a clearer insight into the nature of the reaction. Experiment 2: Simultaneous Addition of Diene. Alkylating Reagent, and Sodium Amide. Three liters of liquid ammonia were condensed in a 12-liter, 3-neck flask, equipped as usual. 1,4- pentadiene (79*0 g, 1.16 m) and methyl iodide (319 6t 2.32 m) were mixed and added simultaneously with previously prepared powdered sodium amide (90.5 g, 2.32 gram atone), which was added by means of a special curved-neek Erlenmeyer flask connected to the reaction -33- flask by a Gooch rubber sleeve. All the Ingredients were added over a two minute interval causing a violent reaction which quickly subsided. Then ammonium chloride was added as quickly as possible to quench the reaction, followed by dilution with water. The organic product was quite volatile and was readily steam dis tilled. The distillate, after drying ( 5 9 * had a very low refractive index (nS° 1.3945). A one plate distillation showed this to be 1,4-pentadiene with the exception of a small amount of high refractive index polymeric residue. The sodium amide had been consumed preferentially in the preparation of methyl iodide; consequently, the 1,4-pentadienylsodium was never formed. Experiment 3s Simultaneous Addition of Sodium Amide and Methyl Iodide to Diene. 1,4-pentadiene (6.8 g, 0.1 m) was added to 250 cc. of liquid ammonia. Then sodium amide and methyl iodide were added batchwise, that is, 0.5 to 1.0 g of sodium amide to give the red salt color, which was then des troyed immediately with methyl iodide. This batchwise addition required nearly two minutes because of the vio lence of the reaction. Ammonium chloride was added im mediately, and the mixture was diluted with water. The organic material and quite a large interface emulsion -34- were steam distilled, yielding only 1*2 g (14?£) of distillate* The residue, a black, water-insoluble, oily substance, steam distilled very slowly (ratio 1/15-20), and the distillate, bright yellow to orange, had an abnormally high index of refraction ( n ^ 1*4977)* Discussion; Experiments two and three were designed to keep the basicity of the solution as low as possible by having the shortest possible reaction time in a moderately dilute solution* Experiment two illustrates the necessity of adding the reagents stepwise to assure the formation of the 1,4- pentadlenj’-lsodium. Experiment three led to excessive poly merization; however, on the basis of previous experiments, the conditions used are those considered to give the best yield of the dlalkylated product. Prom this study, it is concluded that the best condi tions for dimethylation of 1,4-pentadiene are; (1) low basicity, and (2) short reaction time. Unfortunately, the author was not able to increase the yield substantially over that of uncontrolled monomethylation. No further attempts were ma.de to improve the yield of 3,3-dimethyl-pentadiene, because other systems are better adapted for this study: systems in which the boiling point differential between the dialkylated product and the monoolefin, resulting from the selective reduction of a conjugated system, is large enough to allow separation by distillation* - 3 5 - 4. Hydrocarbons from raonoallylation of 1,4-pentadiene Experiment li Kirh. Dilution and Short Reaction Time Reaction conditions found most favorable for monomethylation of 1,4-pentadiene were followed in this experiment* 1,4-pentadiene (224 g, 3.3 m) was added to the sodium amid© (117*0 g, 3.0 m) in five liters of liquid ammonia. Allyl chloride (229.5 g, 3.0 m) was added in five minutes. The rate of addition was delayed somewhat because the reaction was so mild, but after a very short induction period, the reaction became ex tremely violent for approximately three to five minutes. As soon as the reaction subsided, the mixture was quenched with ammonium chloride and diluted with water. The organic layer which separated was steam distilled to give a light yellow distillate, which, after drying, amounted to 221 grams (n^20 1.4510). The residue (about 35 grams) was dark red in color and polymeric. The steam distillate was distilled under vacuum to give 59 grams (1 8 .5^) boiling over 0. 1 ° range (45.5° - 46.5°C/l00 mm). The head temperature was approximately 60 °C when the ‘contents in the flask poly merized so rapidly that a small explosion, violent enough to separate the still pot from the column, occurred. Ho 1,3-pentadiene was found in the trap material. -36 The recovered material was redistilled on the same vacuum column as above to produce 43.5 grams of good 3-vinyl-l,5-hexadiene (b.p., 45.0 - 45.2/100 ram, n 1.4330 - 1.4336). This represents a yield of 13.7/® based on 1,4-pentadiene. A heart cut was taken for the properties which are listed below: 3-vinyl-1.5-hex adi ene This work Literature (l) , *0 P.p (m.p.) C glass ------B.p°C/760 ran 102.80 103.0 - 103.5 20 d 4 0.7445 0.7410 n 2S 1.4334 1.4301 MR found 37.64cc ■IR calc 37.74cc The carbon skeleton was proved by hydrogenation of a 60 gram sample over 6# its weight of U.O.P. nickel at o o 35 C - 150 G. The hi^er temperature was necessary be cause the rate of hydrogenation slowed considerable after approximately 80# of the theoretical amount of hydrogen had been absorbed. The theoretical amount, within experimental error, of hydrogen was finally absorbed. The hydrogenated material (n^P 1.4036) was treated with aqueous potassium permanganate at 0°C for 24 hours, then distilled to give a 78# yield of 3-ettoylhexane. This product would not crystallise; 3-ethylhexane is one of -37 the several hydrocarbons which have never yielded to attempts at cryoscopy. Properties of 5-EthvIhexane This work Literature (63) F,P (m.p,)°C glass ~!?~i 113.7 4 0.7134 0.7128 1.4023 1.4021 Since the carbon skeleton had been proved by hydro ronation, the presence of three double bonds (according to the amount of hydrogen absorbed) proved that the un- snturated hydrocarbon was e s sentially 3 -vinyl -1,5-hex a - diene, as indicated by the method of synthesis and by comparison of its ohysicsl properties with those pre viously reported. The other possible structures are 3 -vinyl-1,4-hexadiene, 4-vinyl-1,4-hexadiene, or 3 -vinyl-2,4-hexadiene, all of which would give 3-ethyl- hexane on catalytic hydrogenation. The most likely impurity would be 3-vinyl-1,4-hexadiene, because if either of the other two double bonds in the system rearranged, then a conjugated system would exist, and this would be indicated by the physical properties. The use of physical properties, however, as a criterion for proof of structure is not as valid in this highly unsaturated system because fewer compounds are avail able for reference unpredictable interaction of groups would be neglected. The supposed 3-vlnyl-l,5-hexadiene failed to fora an adduct with raaleic anhydride in saturated benzene solution when sealed in a tube and heated on a steam bath for 24 hours. Furthermore, the hydrocarbon was Judged to possess little or no conjugation from its ultraviolet absorption spectrum. The molecular refraction found is in good agreement with that cal culated and shows no exaltation due to conjugation. With this evidence to substantiate that obtained from physical property comparison, it can be assumed that the hydrocarbon is essentially 3-vinyl-l,5- or 3-vinyl-l,4- hexadiene. A 1.0 gram (0.01 moles) was ozonized in n-pentane o at -80 C. However when an attempt was made to decompose the ozonlde over Raney nickel, according to the instruc tions of Cook and Whitmore (32), the resulting material was a black, gummy mass. The n-pentane was decanted off and distilled. The various fractions were washed with the water through which the exhaust gases had been bubbled, but the wash water gave only a trace of formalde hyde derivative when treated with recrystallized dimedone in alcohol. An infrared spectrum of the hydrocarbon did not possess any type II olefin absorption bands, but there was a weak band at 11.23 microns which could be a type -39- Ill olefin. Thie would indicate that the hydrocarbon is essentially 3-vinyl-1,5-hexadiene with a trace of the conjugated material as an impurity. Further proof of Identity was obtained by ally lation of 3-vinyl-l,5-hexadiene to the di&llylated product, 4,4-divinyl-l,6-heptadiene In 12.2^ yield Hun 2: The same procedure as used in run 1 was repeated on a 0.1 mole scale at -70°C which yielded 0.3 gram (7»5/0 boiling In the range of 3“Vinyl-1,5- hexadiene. The remainder of the distillate had an extraordinarily high refractive index ( m P 1.4350) which Indicated conjugation. There w b b no indication of any unconjugated higher boiling material when the residue was roughly distilled under reduced pressure* The last drop which would distil came over below the expected boiling point of the eleven carbon fraction; however, there was a fairly large residue. Thus the use low temperature in the allylation did not stop polymerization or rearrangement to any degree* Discussion: The yield of 3“Vinyl-l,5-hexadiene was relatively low, but when the complexity of the unsaturated system In the presence of sodium amide is taken into consideration, it represents a fair yield. The reaction conditions, high dilu tion and short reaction time, help to control rearrangement, - 4 0 - but by no means eliminate it. The unexplained induction period was, in a. sense, a beneficial factor because the ma jority of the allyl chloride was added before any appreciable amount of reaction had occurred and, thereby, the reaction time was reduced. The absence of a higher boiling flat from the 0.1 mole cannot be construed to mean that diallylation did not occur because a small yield could have been retained in the poly meric residues. It does indicate, however, that diallyla tion was not the predominate mode of reaction. On a larger scale, a small amount of the diallylated material would probably be Isolated. This procedure (short reaction time raid high dilution) is considered to be optimum for monoally- lation but does not completely exclude diallylation. 5. Hydrocarbons from diallylation of 1,4-pentadiene Sxnerlment Is One step Procedure , - 1,4-pentadlenylsodium was prepared from sodium amide (97*50 g, 2.50 m) and 1,4-pentadiene (175*0 g, 2.54 m) in five liters of liquid ammonia. To this mixture was added allyl chloride (3S2.5 g, 5.0 m) and sodium amide (97*5 g, 2*50 m) stepwise: that is, approximately 2.5 m of allyl chloride, then 2.5 m of allyl chloride. The time that elapsed during addition was seven minutes. A vigorous reaction ensued, but there was no induction period observed. The reaction - 4 1 ir?.3 quenched with ammonium chloride and treated as usual. Steam distillation gave 340 5 (n*cP 1.4760) after drying, which was vacuum distilled at about 5-6 plates efficiency to give 12.0 g (b.p. 25- 30 C°/l00mn, 1.4325 - 1.4395), which was redistilled and identified as chiefly 3 “vinyl-l,5-hexadiene. The distillation was discontinued at this point and the residue was reduced by sodium in liquid ammonia to destroy the multiple conjugated systems present. This required 175 £ (7*6 g at) of sodium. The blue color would disappear very slowly in the latter stages of the reaction so that the mixture was allowed to stir four hours with excess sodium before back titrating with sodium nitrate. The reaction products were not re duced in the original reaction mixture (even though the diallylated product was the desired product) for three reasons: (l) excessive polymerization results from adding sodium to conjugated hydrocarbons; (2) the titration end-point is difficult to ascertain with colloidal iron coloring the mixture; and (3 ) it was desired to isolate any of the monoallylated product present. After quenching the reaction mixture with ammonium chloride and diluting with water, the hydro carbon layer was recovered and steam distilled to yield 250 g (n^P 1.4372). This material was vacuum distilled at 5-6 plates to give two distinct flats. The lower boll- - 4 2 - irg flat (102 g) was stripped off rapidly "between o 2^-30 C under reduced pressure "because this was assumed to h > predominately the monoolefin re cult In g from re duction* The higher boiling flat (b.p., 40-42° C/t<>mm; n?P 1*4505 - 1*4515) produced 44.0 g or (13,'' of charge). The polymeric residues amounted to nearly 30;£ of the charge• The lower boiling flat was redistilled at 15-20 plates to give an inseparable mixture (b.p. 118.5 - 121.0°C, nlSP 1.4198 - 1.4240). This mixture was essentially identical to the eight carbon fraction obtained on reduction by sodium in liquid ammonia of the reaction products between sodium acetvlide and allvl * « ¥ chloride which was identified as a mixture of 3- ethylhexenes by hydrogenation to 3 - e t ’ ly 1 hex ane, and comparison of physical properties Composite Properties of 3-ethvlhexene mixture From 1.4-nentadlenvl- From sodium acetyl- sodium Ida B.p°C/760 118.9 - 120.28 119.36 - 120.72 d^£ 0.7342 0.7354 n^P 1.4215 1.4217 The material on the upper flat was collected and redistilled under reduced pressure on a column rated atmospherically at 5-6 theoretical plates to produce 35.2 grams (b.p. 51.0 - 51.5/15 mm, n|P 1.4500 - 1.4507* -4 3 - 5.95* based on theory) of 4,4-divinyl-l,6-heptadiene. A small sample of it decomposed when an atmospheric boiling point determination -was attempted. A heart cut v;as taken for properties which are listed below: 4.4-dlvlnvl-l.6-hentadlene Predicted F.p (m.p. glass B.p °/C 760 mm 161 - 162 CH: found CK: calc MR found 51.10 cc MR calc 51.12 cc (a) Estimated from reduced pressure b.p. by nomo graph (53) (b) B.p* estimated from 4,4-diethylheptane The purity of this hydrocarbon was not very good as it contained some close boiling impurities according to the refractive index spread and the boiling point range* An infrared spectrum Identified the very strong teminal olefin absorption bands, but indicated the presence of a trans type II olefin; however, there was no good reference spectra available to determine any interaction of groups vrhlch might give an absorption band at 10*4 mm. To prove the carbon skeleton, a 25 gram sample was hydrogenated over 6 % its weight of U.O.P, nickel catalyst - 4 4 o at 80 C* Hydrogenation slowed considerably after proceeding to approximately QOfZ of theoretical. The temperature wob raised gradually to 150° at 1800 psi, but no more hydrogen was absorbed. After being steam distilled and dried, the hydrogenate was returned to the bomb with fresh U.O.P, nickel catalyst and hydro genation was resumed for four hours at 175° C; at that time, the slow absorption of hydrogen ceased. The hydrogenate was filtered of catalyst and treated with aqueous potassium permangana.te for 1 2 hours at 5-10 . Fractionation of 22.0 grams gave 15,8 grams (b.p., 183.0 - 183.4°C, n?P 1.4284 - 1.4285) of 4,4-diothyl- heotane identified by comparison with a sample prepared by an alternate synthesis (see page 70 ). The hydro genated material distilled essentially as a single compound; except for a fairly large head cut 4.8 grams (b.p. 169 - 182°C, n^P 1.4105 - 1.4280) and a small tail cut (0.8 grams, b. ;. 133.8°C, n^P 1.4333) only 4,4- diethylheptane was present. Its infrared spectrum com pared very favorably with that of the known. The good yield of 4,4-diethylheptane indicated that the unsaturated hydrocarbon was essentially the diallyla- ted derivative; however, as in the case of the mono- allylated derivative, hydrogenation could not prove the position of the double bonds* Since exhaustive reduction in sodium and liquid ammonia had certainly destroyed all - 4 5 - conjugation and since the carbon skeleton was proved, the only likely close boiling impurities of an olefin (type II) would be 4,4-dlviqflL-l, 5-heptadiene end 4,4- divinyl-2.5-heptadiene. Ozonolysis was not attempted because of the unsuccessful experience with the mono- allylated derivative* The success of the experiment was incomplete be cause the impurity present was not postively identi fied; however, there is sufficient evidence that diallylation product did occur in fair yield. Experiment 2 i Two Step Procedure Sodium amide (12,0 g, 0,31 m) previously prepared, was added to one liter of anhydrous liquid ammonia, 3-Vinyl-l,5-hexadIene (36.0 g, 0.33 m) was added rapidly, causing a vigorous reaction. Salt formation was indica ted by appearance of the characteristic red color. Allyl chloride (23.0 g, 0.3 m) was added as quickly as possible with a very vigorous reaction ensuing; however, the reaction subsided near the end of the addition of the chloride. The mixture was allowed to stir ten minutes before it was reduced in situ by sodium (19.2 g, 0.84 g at). The dilution was considered high enough that polymerization caused by this*inverse addition** of re agents would be negligible. After the mixture was quenched by ammonium chloride and diluted with water, the organic material was steam distilled to yield 24.9 grams -46- (53/)* Fractionation under reduced pressure yielded the same two flats as observed in one step diallylation from 1,4-pentadiene. The upper flat, 5*8 grams (b.p. 42- 43/10 mm, r ? £ 1.4495 - 1.4515, 12.2^ yield), was identified as 4,4-divinyl-l,6-heptadiene by comparison of its properties to those prepared by the one step diallylation. Discussion; The diallylated product of 1,4-pentadiene, 4,4- divinyl-1,6-heptadiene was the hydrocarbon desired for engine test purposes. The overall yield obtained by the two-step process was only 1.7f» based on 1,4-pentadiene, which is very poor in contrast to the one-step procedure (8.9^ overall). This is further proof that in liquid ammonia the shortest possible reaction time and minimum basicity are best for diallylation. The various reaction products obtained were analysed closely for an indication that a new active methylene hydro carbon might have been formed by rearrangement of 3-vinyl-1,5- hexadiene: The 11-carbon tetraenes obtained in this reaction series would, on hydrogenation, yield Hftp — | ■CH-CH* h -c h -c m * 4 # 0*Gtf—QH£ 0Ha-GHaC^| -47 3 .4-dlethylheptane, which can be predicted to have a boiling noint greater than 4,4-diethylheptane because of its carbon skeleton. The relation of the physical properties of hydro carbons to their structure has been reviewed by Boord (54). A specific example for this case; 3.3-dimethylhexane (b.p,111.0°C) boils 3*6°C lower than its structural isomer 2,3 dimethylhexane (b.p. 115.5°C). Therefore, since there was no higher boiling material present in the hydrogenated pro ducts the possibility of much 3*4-diethylheptane formation was small. There was no evidence of 4-ethyl-1,4-hexadiene (predicted properties b.p. 119° - 120° C, n?P 1.4336) in the material obtained by reduction by sodium in liquid ammonia; however, its absence was not very significant since re arrangement to its conjugated isomer on contact with sodium amide and then reduction by sodium was expected. If such a sequence had occurred, then in addition to the 3 -ethylhexene mixture, one would have expected els and trans 4-ethyl-2- o hexene (predicted b.p. 118 C), which on hydrogenation would give 3-ethylhexane. However, since 3*4-diethylheptane was not present, the probability of a new methylene carbon being established without further rearrangement to a crossed conjugated system in the presence of sodium amide was con sidered remote. The presence of some 3-vinyl-1,5-hexadiene, even though only h % 9 is significant In view of the fact that no 3-methy1- 1.4-pentadiene was obtained in any of the attempts at -48- dimethylation. There was no obvious difference In rate of salt formation between 1,4-pentadiene or 3 -vinyl-1 ,5 -hexadiene* Rowlands (2) found that 3-phenyl-1-pentene formed the sodium salt very slowly, and he postulated the following equilibrium to explain this difficulty. The electron releasing ability of the alkyl group was great enough to make 3 -phenyl-l-pen- tene such a weak acid that ammonolysis of the salt occurred, C*H. I I — C — CH — CHg ♦ m ^ C^Bg — C — ( f ® CB ♦ BtMHg ‘ IB m b 5.©., the equilibrium was shifted to the right. Even though all the factors, such as: high concentration of ammonia which acts as an acid; solubilities of sodium amide and the hydro carbon are quite low In liquid ammonia, whereas the hydro carbon salt la soluble; and an electron releasing group In the hydrocarbon; are present and would tend to shift the equilibrium to right, the acid strength in the aliphatic series Is still great enough “to drive the equilibrium almost entirely to the left. However, there is the possibility that experimental conditions varied enough “to allow isolation of a small amount of 3 -vinyl-1*5 hexadiene, whereas, any 3-methyl-1,4-pentadiene, which would be expected to show the same, if not greater, electron releasing powers, was rearranged. Every obvious measure was taken to standardize experimental conditions, so that the true nature of the —4 9 “ reaction could be studied* If one may assume identical conditions, then it would appear as if another effect is helping to drive the equilibrium to the right* The spatial arrangement favors an interaction of groups as was shown by H*C-CH - CH - O H * G % i OH - CH-GH* Levy and Cope (l) in their work on rearrangement of allyl groups in three-carbon systems* Therefore, it may be that a combination of the various factors shift the equilibrium a small degree to the left, and thereby explain the presence of come 3 -vInyl-l,5 -hexadIene* The reaction 1b complicated further in that any excess sodium amide could react preferentially with allyl chloride yielding hexatriene or the other self-condensed allyl chloride products as reported by Kharash and Stemfeld (33)* The most likely product was chloromethylvinylcyclohexene, which on treatment with sodium would yield 4-methyl-e-vinylcyclohex- ene or 2-ethyl-3-niethylcyclohexene* However, the concentra tion of sodium amide was low enough that this undeslred reaction evidently did not occur. Excessive polymerization is one of the controlling factors in this experiment as in all the systems studied in this work* It could not be controlled by lowering the reacting temperature, and the use of much higher dilution was impractical* - 5 0 - C. Experimental and Discussion of 1,4-Keptadiene. 1 , Frepara/tion. Experiment 1? Catalytic Hydrogenation of I-Heoten- 4-yne* The synthesis of l-hepten-4-yne used for the preparation of 1 ,4-heptadiene- is described in detail In a succeeding section (see pace 94). 1 -Hepten-4yne (46.5 g* 0.49 m) was diluted with 25/cc, of n-pentane and hj'drogenated over 2 .7^ Its weight of palladium- on-barium-sulfate catalyst at 3 0 ° and a maximum 40 psi of hydrogen. The catalyst was prepared as reported by Schmidt (34) and Paul (35). The rate of hydrogen absorption remained nearly constant (0*3 psi/min) at o 30 (water controlled) until 80,^ of the theoretical amount of hydrogen had been absorbed, the rate di minished (0.18 psi/min) Bomewhat but hydrogenation was continued until 90/J of the theoretical amount of hydro- 20 gen had been absorbed. The hydrogenate (n d 1*4197) was filtered free of the catalyst and stripped of n-pentane* Fractionation at 15-20 plate efficiency gave 18.7 grams (47# yield) Of constant boiling material and 7.4 grams (18* 5^) of material considered as redistillables of the same flat* The residue was chiefly unreduced 1 -hepten- 4-yne. Physical properties of the composite were taken and -51 listed below: 1 .4-Keptadlene This work Predicted F.p(m.p. ) ,° C. glass B.p.,° C/760 mm 93.08 93.0 100-101.5 90.8 0.7161 0.730" 0.7270 0.7120 20 n d 1.4172 1.4273" 1.4370 1.4171 CH CH calc. MR found 33.78 MR calc. 33.59 (a) Predicted from properties of 1-heptene, 3 -bepten© and n-heptane. The purity, as Judged from the constancy of the boiling point and refractive index, apparently was good. However, the unusually large redistlllable fraction indicates the presence of a close-boiling impurity which was assumed to be 1-heptene (93.62°C.). The redistlllable material (n 1° 1.4151) had a depressed refractive index which further substantiated the pre sence of 1 -heptene (n^P 1 .3 9 9 8 ). The cryoecopic behavior of the 1,4-heptadiene indicated that it was not a pure compound. A small sample could be made to crystallise, but when suffi cient material for a freezing or melting point was used, a glass was formed. The failure of 1,4-heptadlene to 5 2 frees© need not be attributed entirely to 1 -heptene as an impurity, for catalytic reduction of the triple bond would be expected to produce some of the trans isomer of 1 ,4-heptadiene as well as the cis (chiefly)* This procedure was repeated several times with slight modifications with no noticeable improvement in yield or purity* Another run was made using U.O.P. nickel catalyst in alcohol as described for alkynes by Oreenlee (3 ), but the results were not as good as those obtained with palladium on barium-sulfate* Discussion; Many catalysts have been reported suitable for the selective reduction of acetylenes to olefins (36) (3 7 ) (33). Palladium on barium sulfate was chosen as catalyst in preference to others from previous results in this laboratory and advice from Howlands (36) who had compared a considerable number of reportedly selective catalysts. The physical properties obtained in the present work agrees but poorly with the inconsistent data reported, and unfortun ately, the chief impurity, 1 -heptene, boils so close that it is impossible to estimate the purity of the product* The one thing observed in the preparation of the cata lyst is that the filtrate on final washing must be absolutely clear and colorless* If there is any turbidity the catalyst is very inactive, and with conditions severe enough to affect hydrogenation, the selectivity is lost. Furthermore, freshly prepared catalyst is much superior to that which has -53- been suitably stored Tor as little as a week. Experiment 2: Reduction of l-He~Pten-4vne by Sodium in Liquid Ammonia, Sodium (23,0 g, 1 g at) was dissolved in 50C cc, of liquid ammonia. To the slowly stirred solution l-hepten-4-yne was added rapidly from a "pressure compensated" addition funnel* Any "salt color" was completely masked by the blue sodium color, A very vigorous reaction occurred without evolution of gas; however, the blue c&lor disappeared after approxi mately 39 grams of the enyne had been added. The hydrocarbon addition was stopped immediately, and ammonium chloride (65,0 g, 1.2 m) was added as rapidly as possible. The reaction mixture was diluted and tv/ice washed with water. The organic layer, on steam distilla tion, gave 32.8 g (n^P 1.4347) of a light yellow material. Approximately 5 grams of a solid, waxy, yellow material which adhered to the walls of the dis tilling flask, was non-distillable with steam. The steam distillate was distilled under vacuum at 5-6 plates efficiency to yield 21.6 grams of material (b.p., 43.7 - 44.8/116 ma; n a 1.4078 - 1.4106). Redistill at ion at 10-12 plates efficiency produced 18.2 g (37^ based on theoretical monoolefin formation) of a mixture of heptanes. By comparison of physical properties this was evidently a mixture of cie and trans-3 -heptene and els -54- and trans-2-heptene. Isolation of the various olefins was not attempted, but the physica.1 properties of the mixture and the shape of the distillation curve indicated a predominance of 3 -heptene* Properties of Heptene (mixture) This work Literature 2-Heptene 3-Heptene Limits trans (33) cis(83) transi_85l 7.p(m.p.) C -109.57 glass -136*67 b.p C/760 mm 95.91 - 96.07 97.95 95.75 95.69 0.7002 0.7031 0.7031 0.6981 1.4058 1.4045 1.4059 1.4044 The only other proof of identity obtained was an infrared spectrum which indicated that the mixture was predominately the trans isomer of 3 -heptene by compari son to known spectra. Discussion; The reduction of l-hepten-4-yne by sodium in liquid ammonia gave predominately alkenes, a yield of 74# based on amount of sodium consumed. The obtained hepten© mixture (18.2 grams, 0.185 moles) would have required 0.75 moles of sodium, based on reduction of an acetylenic group to an oloflnic, then subsequent reduction of a conjugated diene to a monoolefin, whereas the actual ©mount of sodium consumed was 1.0 moles. The remaining 0.25 moles of sodium could reduce only 0.125 mole£ of original material, which means that at least 0.11 moles (27/0 of 1 -hept en-4-yne was never reduced. If any of the monoolefin was consumed copolymerization or lost mechanically, then the amount of unreduced l-hepten-4-yne would he increased* Further more, the waxy nature of the non-steam dlstlllable material Indicates "the polymer may have been hardened by reduction* The most slgnifleant observation of this experiment, other than that 1,4 enynes can not be reduced by sodium In liquid ammonia successfully to the correspondin'? 1,4 dienes, If the relatively good yield of the mono-olefIns* This serves as a basis for an inference that a conjugated diene system is reduced preferentially to a dialkylacetylene by soclum In liquid ammonia* However, 1,4 envnes are not "true” dialkylacetylenes because the hydrogens on the adjacent methylene group are activated end could possibly react with sodium to form the 1,4 enynylsodium. The hydrogen dis placed could reduce the triple bond either intra- or inter- molecularly, resulting in the formation of a 1,4 dienyl- sodlum. There is also the possibility that the 1,4 enynyl sodium Is In equilibrium with a conjugated enynyl sodium which would be ammonolyzed immediately to generate sodium amide and the conjugated hydrocarbon; this system would surely be re duced to produce an alkene. The sodium amide thus formed accelerates the rate of rearrangement. Furthermore, if the triple bond were reduced by sodium, In lieu of 1,4 enynyl sodium formation, the resulting 1,4-diene could then be -56- (X) R-C*C-CH*-CK«CH, ♦ *-C)-CB»CH« + £ V J {2) R-CxC-CH(JI* )-CH«CM. ^ R-C (,«* )*C«CH-CH"CH* or R-C *C-Gff*CH-CHa (M* ) (3) R-CUla>C«CB-CH-CH* ♦ MR* — * R-CH*C-CH-CH-CH. ♦ MaJfH. R-C*C-CH*CH-CH.(lift) ♦ — *- »-C»C-CH*Cii-CH, ♦ J**B. (4) K-C* C-CH.-CH-CH, 4 «{jQ — * R-HO*Cii-Cj%~Gll* CH. . J- ...I . , I ■ ;„r .. - - kj ' ■ by codi'm ?,nide and a rc-actlon echene similar da that postulr.ted above would be applicable. However, the a^' ter the amount of triple bond reduction, the correspond ingly lower yield of alkene. Considering the yield of allcene in the light of the 'mount of sodium consumed, it is obvious that- the conjugated dime or enyne, regardless of mechanism by vrhlch conjugation occurred, are reduced preferentlally when in competition with e triple bond contained in an 1,4 enyne. Greenlee (3) in an attempt to reduce l-octen-4—yne, odded sodium until the blue color persisted, but, even then, no clean-cut reaction occurred. He found the amount of sodium required for complete reduction of the hydrocarbon corresponded to 1*7 bonds. The high index of refraction of the hydrocarbon recovered indicated polymer formation. These results are in accord with the present work. The absence of any 1,4-heptadiene or any unreacted 1-hepten-4-yne is not surprising because the alkylation ex periments have indicated that a very low concentration of -57- ro liun amide will bring about complete rearrangement of ruch hydrocarbons. However, the complete absence or any oozijug?-ted monomer was not anticipated and con only be explained by its involvement in the polymeric material* 2. Hydrocarbons from Monomethylation of 1,4- Heptadiene The conditions found most suitable for mono- nethylatlon of 1 ,4-nontadiene were used in this ex- perimont* To form the sodium derivative, 1,4-hepta- dioiie (53 g, 0.55 m) was rapidly/ added to sodium amide (0.5m) in two liters of liquid ammonia* The heat effect was much less than in the case of 1 ,4-p©ntadione, but salt formation was Indicated by appearance of the charactoristic red color* k very rapid addition of methyl iodide (71*0 g, 0*5 m) required only about a minute; however, the red color disappeared after approximately 70% of the halide had been added* The mixture was quenched, hydrolysed, and steam distilled as usual. 20 The crude, (37*9 grams, n d 1*4386) yielded on fractionation under reduced pressure 17*3 grsms (n 1.4364) boiling below 110 C* The remainder was roduced by sodium (7.9 grams) in liquid ammonia to yield 10*3 grams of a monomethylated mono-olefin mixture which was apparently Identical to the mixture obtained by reduc tion of the methylation product of l-hepten-4-yne (see page 93) -58- There was no Indication or any higher boiling product. Mixture of 3-I’Iethvlheptenes From 1.4-nentadiene From 1-heoten-4-yne B.p. ,°C/760 ramnun. 121.0 - 123.0 121.43 - 122.69 0.7322 0.7318 1.4174 - 1.4187 1.4175 - 1.4182 (a) Uncorrected. The lower boiling material on fractionation at 20 (b.r. 102.8 - 110 C; n 3 -Methyl-1.4-hentadlene (els and trens) F.p. (m. p. )° C B.p,° C/7^0 mm 104.8 - 105.0 105.0 - 105.5 0.7290 0.7298 20 n d 1.4248 - 1.4250 1.4246 - 1.4248 MR found 38.21 I® calc 38.45 -59 A sample (3.2 grams) of I've best product was hydrogenated to saturation over 5 .Op of itE weight of U.O.P. nickel catalyst. Fractionation at 3-5 plates efficiency yielded mostly 3 -m ethyl -heptane; however, 8p was low boiling headings, which indicated the pre sence of some n-heptene. Run 2 t A smaller run(0.16 mole) was repeated with the same procedure; however, the mixture was Etlrred for five minutes after the red salt color disappeared on addition of the halide. The color did not reappear end the reaction was quenched and product recovered as usual. Tho crude (P.5 grams, n20 & 1.4405) represented a recovery of only 54-fa, which indicates that polymeriza tion, as well as rearrangement, increased substantially d u r i n g the longer reaction time. Pi rrcusslon: Tjie rearrangement of 1,4 dienes to their conjugated isomers in the presence of sodium amide in liquid ammonia is greatly enhanced b^r replacing either a peripheral hydrogen atom or a methylene hydrogen atom with an alkyl group. The second run of this series proved that "he color disappearance was not the result of insufficient tine for the salt to eom, as vras the case in tho aromatic series (Z) , but vras the result of rearrangement of the 1 ,4-heptadiene. The low-boiling mixture was most certainly a mixture of 1 ,3-hoptadiene and 3 -methyl-1 ,4-heptadiene, both of which —60— can exist In geometrically isomeric forms, since hydro- gonation proved the carbon skeleton and Indicated that a straight chain seven-carb6n diolefin was the conjugated impurity. This experiment exemplifies the critical nature of the experimental conditions. The time lapse between the reac tion forming the salt and the addition of the halide must be as short as possible in addition to a very short reaction time. In the case of the sodium derivative of 1,4-penta- diene, these factors were somewhat less important. 3. Hydrocarbons from Dimethylation of 1,4-Keptadiene An attempt was made to dimethylate 1,4-heptadiene (53*0 grams, 0,55 moles) by adding it and methyl iodide (142 grams, 1.0 mole) simultaneously to sodium amide (1.0 mole) in two liters of liquid ammonia. The addition rates were adjusted to maintain the salt color; however, less than half of the iodide was added when the color; faded. Immediately, sodium (14.0 grams) was added until a blue color existed. Fractionation of the 20 crude 34.1 grams (n a 1.4133) produced 10.6 grams (b.p. 95.0 - 9 6 .0 , nIP 1 .4060 - 1.4091) (31.2#) of the n-heptene mixture, as obtained in reduction of 1 -heptene- 4-yne by sodium in liquid ammonia and 15.0 grams (b.p. 121.0 - 124.0°C; n1P 1.4170 - 1.4198) <-44.0^) which was Identical to the 3 -methylheptene mixture obtained in the monomethyl at ion experiment. There was • 61 — a little material (2*8 grams) which distilled above the second flat which indicated perhaps a trace of 3 ,3 -dimethyl -1 , -4-heptadiene * Discussion: The replacement of a methylene hydrogen and a peripheral hydrogen atom by an alkyl group in 1,4- dienes accelerates rearrangement to the extent that the amount of dimethylation is or less* This result is in agreement with the attempted dimethylation of l-hepten-4-yne. III. Alkylation and Rearrangement Reactions of 1,4 Enynyls* A. Historical and General The use of 1,4 enynyls as intermediates has re ceived very little attention. For one reason, there was no general method of preparation of these sub stances until 1928 when Grignard and coworkers (39) (40) reacted alkynylmagnesium bromides with allyl bromide. However, in 1931» they (4l) were not able to repeat the preparation of l-penten-4-yne from allyl bromide and acetyleneraagneslum bromide* Danehy, Killian, and Hieuwland (42) were able to duplicate the results, but only after adding cuprous salts, preferably cuprous chloride, as a catalyst to promote the reaction. With out the catalyst, they found that alkynylmagnesium bromides failed to react with allyl bromide over a pro longed period of time. They concluded that impurities of copper in the magnesium used by Grignard may have been responsible for his earlier success. Grignard and Lapayre (39) measured the relative acidity of the hydrogens on the activated methylene carbon in 5 -phenyl-1 -penten-4-yne and 1 decen-4-yne. They found that the reaction with sodium was indiffer ent, slow, and Incomplete, the reaction with sodium amide in benzene, with the liberation of ammonia, was nearly complete at 70°C, and the reaction with ethyImagneslum bromide (Zerewltlnoff) was 80 - 90# -03** o o complete at 70 C, but only 40-50J& at 35 C. Lespieau and Joumaud (43) were the first to metalate and allylate l-penten-4-yne. They were attempting to prepare allyl acetylene by reacting allyl bromide with sodium acetylide, but obtained, eight carbon and eleven carbon products, Instead. Greenlee (3) ran a preliminary experiment on the ethyl at Ion of l-octen-4-yne and obtained a product which gave a 35-40^ yield of 3 -ethylhexane upon hydro genation. He used, as is now clear, conditions con ducive to rearrangement and, consequently, recovered only the conjugated monoethylated derivative. There has been little study made of the reactivity of -methylenlc hydrogen adjacent to a triple bond in comparison to a double bond. Grignard and Lapayre con cluded that 1,4-diynes activated the methylene hydrogen more than 1,4-enynes because l,5-diphenyl-l,4-pentadiyne reacted more completely with ethylmagneslum bromide at a lower temperature* This disubstituted aryl diyne may possess more active hydrogen, but, most certainly, it was not proof enough to make a broad generalisation. Prom known relative reactivities of allylic and pro- pargylle halides, the reactivity of dl-methyl enic hydrogen in 1,4 enynes is predicted to be less than in 1,4 dlenes; yet the methylenic hydrogens of 1,4-enynes are considerably more acidic than acetylenic hydrogen -64 as shown by the apparently anomolous results obtained by Lespieau and Joumaud* The fact that the raonoally- lated derivative was the predominant product with a smaller yield of the diallylated product can be explained in one of two ways: (1 ) after replacement of one hydrogen on the methylene group the acidity is reduced considerably; (2 ) during allylation rearrangement occurs yielding a conjugated enyne, the salt of which Is immediately amnonoly2ed. The latter Is considered to be the most plausible because the eight carbon fraction was conjugated as Indicated by its physical properties and a high molecular refraction due to exaltation from conjugation; however, Lespieau and Joumaud were of the opinion that their main product was the unconjugated Isomer* Furthermore, they also reported a five carbon fraction, probably 2-penten-4- yne, which is evidence that some rearrangement had occurred* Greenlet* (3 ) also repeated this study in an attempt to Isolate this low boiling product, but he was unsuccessful* The reaction of allyl halide and sodium acetylide was repeated for the following reasons: (l) the elucidation of the reported reaction; (2 ) a comparison of l-penten-4-yne versus 1,4-pentadiene in i allylation; (3 ) the preparation of the hydrocarbon containing four points of nonconjugated unsaturation desired for ermine-test purposes. An enyne containing an interior triple bond was methylated in order to compare the effect, if any, of the terminal triple bond, l-Hepten-4-yne was chosen for the purpose. 2, Hydrocarbons from Dlallylation of l-penten-4-yne Pxrerlment 1: Ratio: two parts albvl chloride to one -part sodium acetvllde. Sodium amide (8 m) was prepared from sodium in five liters of ammonia in a 1 2 -liter flask according to the usual procedure. Tank acetylene was purified by passage through a train consisting of two concentrated sulfuric acid-filled scrubbers and a drying tower of anhydrous calcium chloride and Drier!to, The purified acetylene was introduced below the surface of the well-stirred mixture to prepare sodium acetylide. Sodium amide (312*0 g, 8,0 m ) , previously prepared, was added bathwise and to the solution of sodium acetylide, yielding a suspension of disodium acetylide, and to this chloride (1225*0 g, 16*0 m) as rapidly as the reflux condenser would permit* This extremely exothermic reaction required nearly two hours. The reaction subsided almost entirely as soon as the chlor ide was all added; however, stirring was continued for an hour. The reaction mixture was quenched with ammonium -66- chloride (2 1 . 6 g, 4*0 m) and diluted with 5-6 liters of water. The organic material did not separate into a. distinct layer but could be isolated by steam dis tillation. A 34 s x ' & m (n IP 1.4690) portion was steam 20 distilled yielding 31 grams (n a 1.4670) and leaving 20 an oily red liquid (n. d 1*5075)* The distillate of the bulk was washed successively with ~L% sulfuric acid, dilute sodium bicarbonate solution, and with 3 0 f> glycerin in water; then it was dried through 20 anhydrous sodium sulfate to yield 655 grams (n ^ 1.4652) or 75*8,^ based on allyl chloride. A .100 gram aliquot portion was distilled roughly from a Claisen head o 20 flask to yield 31 grams (b.p. 49.0 - 55.0 C, n d 1.4311- 1.4350); then the residue detonated with violence enough to crack the flask* The remainder (555 grams) was vac uum-distilled at 5 - 6 plates efficiency to yield 145 grams of low boiling material which was collected in a Dry Ice-cooled trap and 55*0 grams (9*9^) on a higher boiling flat (b.p. 36.5 - 38.5°C/5mm, nlP 1.4649 - 1.4660). The residue (255 grams, 46.0^) was dark red in color and syrupy in consistency. The low boiling material (145 grams) on redistill ation at 10-12 plates efficiency had one definite flat of 124 grams (b.p. 43*5°0 - 44.0°C/734mm, n^0 1.4223 - 1.4334)* Every fraction gave a positive Beilatein test for halogen and colored immediately on standing at - 6 7 - room temperature tinder a nitrogen atmosphere. This was considered to be predominately allyl chloride with some 1-penten-3-yne or 2-penten-4-yne as the most likely impurities. However, the boiling point was nearer that reported for l-penten-4-yne. When 15 grams ° ? "this material was reacted with sodium In liquid ammonia, the only product isolated was 2-pentene in less than 3 % yield. This did not solve the problem because 1,4 enynes have been shown to reduce as if they were conjugated. Unfortunately, at the time this research was carried out, the behavior of 1,4 enynes in presence of sodium had not been studied and any 1-penten-4-yne was expected to produce 1,4-pentadiene* Since only 2-pentene was isolated and from the be havior of the material on standing, the impurity of the allyl chloride was considered 2-penten-4-yne. Further more, this definitely was not the five carbon fraction reported by Lespleau and Journaud. The remainder of the material was bulked and added as allyl chloride ts an other run. The higher boiling flat was redistilled under vacuum to yield 50.0 grams (6.5/0 oi* constant boiling material (b.p. 52 /18mm, n?P 1.4644 - 1.4645) which was identified as 4-ethynyl-4-vinyl-l,6-heptadiene. (See i page 8 3 ) for physical properties determined on a much larger sample.) This material did not give the - 6 8 - characteristic oi-acetylenic chemical test in that it was Impossible to form tho cuprous (48), silver (49)# or mercuric derivatives (50)• However, the acetylenic group absorption band was very prominent in its infrared spectrum. Also, from its spectrum it was possible to distinguish only terminal olefins with no indication of any other type being present. An attempt was made to reduce the acetyl©nic group by sodium in liquid ammonia (47) by adding 32.0 grams (0.3 mole) of the constant boiling material and 50 grams (0.3 mole 2 5 /£ excess) of ammonium sulfe.te to one liter of ammonia. This mixture was well stirred and 15.2 grams (0.6 gram aton 10;^ excess) was added piecemeal. The characteristic blue color of sodium disappeared slowly, and hydrogen wa.s evolved, both facts Indicating that very little reduction of the organic material was occurring. The reaction mixture was allowed to stir for one hour and in later runs an excess of 2 0 0 ^ Na and ITHj^)2 So^ over a long period, with little or no decrease in refractive index of the hydrocarbon which was recovered by steam distillation. The carbon-hydrogen analysis gave results consistent with composition CxiKx4 (calc. for CxiHxa; C, 90.34; K, 9.66. Found C, 90.17 and 90.40; H, 9168 and 9»64). i The carbon skeleton was proved by catalytic hydro genation of 40 grams of the diallylated material over —69** 6 .Jft of* Its weight of U.O.F. nickel catalyst. Hydrogen absorption did not occur until the temperature bad been o Increased to 100 C with an initial pressure of 1300 psi* After 30^ of the theoretical amount of hydrogen had been absorbed, it was necessary to remove the charge, steam distill, and dry. This material was returned to the bomb over fresh catalyst and this time heated to 175°C for 24 hours before the very slow absorption of hydrogen ceased. Some decomposition and polymerisation had occurred on hydrogenation because of a small amount (approx. 2-3 grams) of polymeric residues* The hydro genate, filtered free of catalyst, still gave a slight unsaturation test by decolorizing a solution of bromine in carbon tetrachloride. Therefore the material was treated with aqueous potassium permanganate for 24 hours at ice temperature. Fractionation at 15-20 plates efficiency gave some low boiling heads, but 82f* of the charge was good 4,4-diethylheptane as Judged by com parison of properties* An authentic sample of 4,4-diethylheptane was pre pared by the following reaction sequence: Propionic o anhydride passed at 500 trver thorium oxide alumina catalyst gave diethyl ketone in & y » 2 % yield; diethyl ketone added to n-propylmagnesium bromide gave 3-ethyl-3-hexanoJ. (b.p. 58 - 5 9 °C/$tam, n?P 1.4320, d^P 0.8393) in 83*4^ yield; gaseous dry hydrogen chlor- -70- ide bubbled through this alcohol produced 3 -chloro- 3-ethylhexane (b.p. 133 - 160° C/760, n ^P 1.4344); and addition of this chloride to n-propyl-rar.gnesium bromide led to 4,4-diethylheptane in 2 2 . 4,c' yield. 4.4-Piethvlheot ane Hvdrorenated Trlenvne Authentic Sample o F.p.(m.p.) C glass glass 1.p.° C/760mn 132.9 - 183.3 183*4 djf0 0.7676 0.7671 n 1.4286 1.4284 The most likely impurity in the hydrogenated sample is residual un3aturatlon which is, perhaps, reflected in its physical properties; ho^./ever, there is such a good comparison to the authentic sample that there can bo no doubt as to the proof of the carbon skeleton. The same is true for the Infrared spectra. Any of the other eleven carbon paraffins would be expected to have a higher boiling point. Discussion; Allyl halides react with sodium acetylide and sodium amide in the pattern visualized by Leepleau and Joumaud; however, those workers failed to identify ary of their products other than to report an unidentified mixture containing eig£it and eleven carbon atoms. Perhaps, no strict conioarlson can be drawn from this experiment with that of L,::r:Ier-u and Joumaud because sodium amide was used in The 4-ethvnvl-4-vinvl-l,*ri «* + * W 6 -heotadion© was the onlv V hvdr V o- rbon which could be Isolated from the complex mixture of • ction products which yives son© indication of its datively high stability* Any eight carbon product was most entirely consumed in formation of polymer sine© there s no flat below the 150°C material* The true nature of ^ reaction is very difficult to elucidate because of the cessive polymerisation. However, since 4-ethynyl-4-vlnyl- 6 -heptadiene was formed, then 1 -penton-4-yne and 3 -ethynyl- "-hexadieno must have been present. Furthermore, the r.ration of any eleven carbon non-conjugated trlenyne iicated a metathetic reaction was proceeding during the dition of the chloride because the amounts of allyl chloride :1 sodium amide used were proportioned to yield the 8 -carbon enyne• Run 2; Effect of Dilution Except for higher dilution, this procedure was identical to the previous run; a mixture of 4 moles of sodium acetylide 4 moles of sodium amide, and 8 moles of allyl chloride was added to 5 liters oa ammonia* The reaction was quenched shortly after completion of addition of allyl chloride. Steam distillation yielded 20 313 grams {n d 1.4806) or 73*8^ recovery. The crude mixture yielded only 12 grams (b.p* 58 - 59°C; n^P 1*4437 - 1.4482) when heated on a water bath to distill any loir boil Inn- material. Physical properties are listed, belovr in comparison iritli those of possible products* Physical Properties of Entries Etc. Compound B.n?C/760ram F.P. d n Keff. 5 carbon fraction 50-59 -- 0.7407 1.4457 pres.res. 3 carbon fraction 62 — 0.759 1.438 Lespieau(43) 1 - — o n t a a - 4 -yn e 41-42 — 0.777 1.3633 (4?) 1-aort on-3 -yne 5 9 .2 — 0 .7413 1.4491 (51) a - 'or.t on-4-yne 59.25 -117.6 0.7413 1.4491 (3) on ta r -4 -yne 46-48 — 1.4356 (52) This low boiling fraction could not be identified by comparison of physical properties. It was a five carbon fraction because reduction by sodium in liquid ammonia gave 2 -pentene. It also gave a weak precipita tion on reaction with amnoniacal silver nitrate and cuprous chloride indicating the presence of an 1 - alkyne. There was no chlorine present as both the Beilstein and sodium fusion tests gave negative results* Furthermore, the material was not of good purity as indicated by its boiling point range. Since 2-penten-4-yne and 1-penten-3-yne have been reported to have nearly identical properties, this material was considered to toe a mixture of these two hydrocarbons. However, it would seem anomalous for these -73- two conjugated hydrocarbons to have identical pro perties when the following lino of reasoning is con sidered. The only evidence which tends to disprove that the low boiling material was not 1 -penten-3 -yne -rentyne 56.2 1 .4034 1 -pentyne 40.2 1.3352 -pentere n-pentane -6 t0 .0142 2 -pentene 0t5. n-pentnne 50.2 1.4177 40.7 1.4082 aborted 1 -pen ten- conjuration 9.0 .0319 ro -yne O » 1 .4496 predict for ffect of 2 -penten- onJugation 9.0 .0319 4-yne 49.7 1.4401 is a qualitative precipitation test with canonical silver nitrate or cuprous chloride. Impurities of 2-penten-4-yne could have been present in concentration great enough to cause weak ©t-acetylenic test* If the latter is true, then the mixture obtained in this experiment is pri marily l-penten-3-yne. It was planned to Isolate and further identify this product, but even though numerous runs were donducted, the five carbon fraction xfas never again isolated* The bulk of the material (boiling over 60° C*) was then distilled under vacuum to yield 65 grams (b.p. 2 6 - 2£? C/l5mm JP 1*4854 - 1*4893* d^P 0*7923) and 39*0 grams (b.p. 43-44°C/10 mm n^? 1.4670 - 1.4679) . The lower boiling flat gave a weak qualitative test for 1 -alkyne and was bulked with like material from later rune. This material was light yellow in color and a sample, on standing under a nitrogen atmosphere in the refrigera tor, gained 30 points in refractive index in 48 hours. After standing nearly a month, a rubbery net of polymer was fomed on the surface that eventually filled the open space in the bottle. The poljmer was insoluble in a variety of organic solvents and, but decomposed slowly in concentrated sulfuric acid. A sample (23g.) of the low boiling material was diluted in 50 cc. of n-pentane and hydrogenated over 5% o o of its weight of U.O.F. nickel catalyst from 70 to 200 at 1100 to 2800 psi. Fractionation at 3-10 plate efficiency yielded 14.0 grains (69/0 of 3 -ethylhexane (b.p. 118.0 - 119.0; n^P 1.4015 - 1.4022). The upper boiling flat was redistilled under vacuum to yield 34 grams (8.7^) of 4-ethynyl-4-vinyl-l,6-h©pta- dione (b.p., 42.0 -43.°C/7tam; A0 1.4640 - 1.4645). Discussions This run definitely established the pattern of the reaction. The sodium acetylide reacted with allyl chloride to form l-penten-4-yne which under went the apparently anomal ous result of allylatlon only at the methylene group* To the extent that diallylatlon occurred with disodium acetylide, it must have been entirely consumed in the polymeric residues. If this type of reaction did occur, a hydrocarbon containing two active methylene groups would have been formed and further allylation leading to a very complex molecule would be expected. -75- However, rearrangement would probably Intervene and stop f u r t h e r allylation; the rearrangement product would give n -o c ta n e on hydrogenation. The hydrogenated eight carbon fraction was examined closely but no Indication of n-octane ( b .p . 125.6°0) was found. Therefore, if allylation occurred a t the acetylenic group, the product was polymerised com p l e t e l y . This same thing would apply to allylation of 3 -3thynyl-l,5 *hexadiene so that, in effect, the reaction p ro c e e d s as If allylation occurs only at the methylene c a rb o n of l-penten-4-yne. Increasing the dilution twofold and decreasing the reaction time had little effect upon the yield of dially- lated product (8.7f*)* but did reduce the rate of polymerisa tion sufficiently to permit Isolation of an eight carbon fraction. Hun 5: Effect of High Dilution at -70°C The procedure was the same as In previous runs of this series, except that the dilution was increased; 2 moles of sodium acetylide, 2 moles of sodium amide, and 4 moles of allyl chloride were reacted In 5 liters o of liquid ammonia which was cooled to -70 C by surround ing the flash with a Dry-Ice acetone slurry. A very vigorous reaction ensued on addition of the chloride, and the mixture was quenched immediately with ammonium chloride. The organic material on steam distillation yielded 165 grams < n ¥ 1.4883}* The crude material was charged to a eolunj^g£or vacuum distillation, but as In previous rune, an attempt waB made to remove the five carbon fraction, A flask equipped with a ther mometer well was used to check the pot temperature, \/hlch was never permitted to exceed 75°C, in order to avoid polymerisation. However, in this run the temper- o ature was only about 60 when the material polymerized so rapidly that a small explosion occurred, which forced the head and not apart from the column. A grandular 11 popcorn-type" of polymer was spread over the immediate area and, on cooling, resembled saw-duet* It was soluble only in concentrated sulfuric acid. Discussloni: Even though reduced pressure distillation of the product was unsuccessful, the large amount of polymeric material obtained and the high refractive index of the steam dir tilled crude made it evident that pol2/merization had occurred to a considerable degree. The low temperature and higher dilution must have reduced the polymerisation to such a degree that less heat was necessary to initiate further polymerization; yet, little or none of the five carbon fraction was present, Ratio 3 Parts Allyl Chloride to 1 Part Sodium Acetylide. The procedure here was identical to that of experiment 1 except that the amounts of allyl chloride and sodium amide were increased to a ratio of 3 parts -77- allyl chloride, 2 parte sodium amide, and 1 part sodium acetylide. Allyl chloride (9 moles) was added in 45 minutes to the mixture or sodium acetylide (5 moles) in 5 liters or liquid ammonia. Steam distilla tion yielded readily 3 0 6 grams (1.4761) and with the aid or a super heater gave 3 $ grams more (n*?P 1 *5 0 3 2 ). Fractionation or the product under vacuum yielded: 96 grams (b.p. 39 . 0 - 4l.O; n^P 1.4288 - 1.4345; d*^ 0 .9 0 2 7 ) or low boiling material, which was pre dominately allyl chloride containing some conjugated hydrocarbon; 66 grams (b.p. 24 - 26/0mm; n^P 1.4840 - 1.4905) or the eight carbon rraction; and 5 7 grams (b.p. 50 -52/ 8mm; n%° 1.4641 - 1.4647 or crude 4- ethynyl-4-vinyl-l,6 -heptadiene. The latter on redis tillation gave 35.2 grams (8 .0 ;») yield or the puriried material. Discussion: The increased amount or allyl chloride did not increase the yield or trienyne appreciably nor did it reduce polymerization. Run 2: Allyl Bromide Allyl bromide was used in place or allyl chloride on a 1.0 mole scale, but the only signiricant dirTer ence was a much lower recovery on steam distillation (64) . No low-boiling product was obtained and only 4.2 grains or the crude trienyne. The material poly merized rapidly during distillation even though an equal volume of dicyclohexyl had been ?„dded as a diluent. Experiment 5: Reduction by Sodium Allyl chloride (462,0 prams, 6,0 mole?,) was added in 30 minutes to a mixture of sodium acetylide (2 moles) and sodium amide (156,0 grams, 4,0 moles) in 4 liters of ammonia. After hydrolysis, tho organic layer on steam distillation readily yielded 193 grams (n 1 ,4671) 20 nd, on forcing, gave 64 grams (n a 1,5033 of a higher boiling notarial leaving only 11 grams as Polymeric residue. The readily steam distillable material ■'fas added dropwise to 115 grams of sodium dissolved in 3 liters of ammonia. This blue color persisted for one hour after the addition of the hydrocarbon was finished. Bach titration by ammonium nitrate indicated 109 grams (4,74 p*.atoms) of sodium had been consumed. After quenching with ammonium chloride and diluting with water, the organic layer on steam distillation produced 145 grams (i?£ 1.4470) and another 12 grams (1.4890)on forcing. The lower index material was vacuum distilled at 5-6 plates efficiency to give 5 grams of low-boiling heads (n|° 1.3894), 31*2 grams (b.p., 51°C - 53°C/6lmm.; 1.4250 - 1.4275), and 34.5 grams (b.p., 52.0 - 54.0° 0/ lOmn; n IP 1.4615 - 1.4630). The latter was principally -79- 4 -ethynyl-4 - vi ny 1 -1 ,6 -hept ad iene representing a yield of 11* 3f£* The low boiling beads and eight carbon fraction were bulbed with material from subsequent runs and identified (see page 82 ) respectively as cia and trans 2 -pentene and a mixture of 3 ”©thylhexenes after reduction by sodium with ammonium sulfate in liquid ammonia. The sight carbon fraction still gave a precipitate with, amnionical silver nitrate and cuprous chloride, PIscusslon: Reduction of the crude reaction mixture improved the yield of the desired trienyne eomewhat, but the most important advantage to this procedure is the ease in handling curing distillation in comparison to the losses occurred by polymerization in the unreduced runs* Run 2; Subsequent runs Two mans were carried out on a twenty mole scale as nreviouslvt * described with the execution *■ that sodium amide was produced In situ instead of adding batchwise to the sodium acetylide* Sodium amide (20 moles) was prepared from sodium .and 6 liters of ammonia. Purified tank acetylene (8 moles or 7*2 STP cubic feet) was metered into the solution-suspension of sodium amide. A wet-test gas meter, accurate to 0*01 cubic feet, was used to measure the acetylene which was Introduced below the surface of the well-stirred -80 reaction mixture. To this mixture was added allyl chloride (1540 grams, 20 moles) as rapidly as possible and allowed to stir for one Hour before quenching wltH ammonium chloride (270 grams, 5 moles) and a large excess of water. The organic material was steam dis tilled and after treatment to remove any residual ammonia (and drying) yielded 860 grams (8 5 .3/* based on allyl chloride) of crude product (n^P , 1.4-781). The resi due amounted to 70 grams; thus, the total recovery of organic material was 9 2 .5/* of theory. The steam distillate was reduced by sodium (851 grams, 37 gram atoms) In 6.5 liters of ammonia. After stirring five hours, ammonium chloride (2000 grams, 37 moles) was added to quench the reaction. Following hydrolysis, steam distillation of the organic material yielded 510 grams (60^ of charge) of crude product (n^P , 1.4470). To complete the reduction of any 1-aLkynes present, the 510 grams of crude was added rapidly to a suspen sion of 3 moles (396 grams) of finely crystalline ammonium sulfate in 2 literB of ammonia and sodium was added piecemeal. The sodium was not consumed rapidly, and hydrogen was evolved; therefore, the addition of sodium was stopped after 2 gram atons of sodium had been consumed. The product, 460 grams, was recovered in the usual way with its refractive index -81- unchanged. The crude reaction mixture from two such runs, plus some material from Bmaller experimental runs, was combined, and the composite (1200 grains) was fractionated roughly under reduced pressure on a column capable of 5-6 plates efficiency. This pre liminary distillation separated the charge into four rather wide boiling flats. gLrvt 1 87 grams (b.p., up to 30 C/lOOmm. ; n2c? 1.3865-1.3915) gr.t 2, 441 grams (b.p., up to 43 C/l3ra:n, ; r? S 1.4080-1.4300) plat 5 , 404 grams (b.p., up to 72 C/llmm. ; n ^ P -1.4512-1.4586) .hove 3Lat 3 , 55 grams (b.p., up to 108 C/7mm.; n Each of the flats was distilled again before final distillation which gave the following compounds. Physical properties were taken on each and are listed below. Mlarture of cie and trans 2 -pentene This work Literature (83) trans 2 -pentene flis 3 -pgp,ft,w ?.p. (m.p.)°C glass -140.26 63-ass 3.P °C/760mm 36.41 - 36.43 36.36 36.96 0.6492 0.6482 0.6538 1.3800 - 1.3801 1.3794 1.3821 -82 Mixture of hexenes This work Literature (83) clg-2 trans-2- cls-3- trans-3 P.P. (m.p.) C glass -144.12 -133.16 -138.30 -113.50 B.p. °C/760 nun 66.8-63.6 68.88 67.91 66.56 67.12 da 2,04 0.6810 0.6859 O.678O 0.6795 0.6772 20 n d 1.3943-1.3987 1.3971 1.3940 1.3950 1.3943 Mixture of 3-ethvlhexenes This work Literature (c&t) 3 -ethyl-2 - 3 -ethyl-3 - ______hexane -1951 hexane (86) F.p. (m.p.) C -- B.p.°C/760 mm 119.36 - 120.72 120.1 - 121.1 119.0 20 d* 4 0.7354 0.7367 0.7318 20 n d 1.4211 - 1.4226 1.4246 1.4204 4-ethynyl-4-vlnyl-1 .6-heptadlene This work Predicted 0-0 F.p.(m.p.) C glass B.p.°c/l3 mm 52.0 B.n.°c/760 rama 167 169.0 a^P 0.8177 20 n d 1.4644 1.4733 MR found 49.32 MR calc 49.59 (a) Estimated from reduced pressure b.p. by nomograph (53) (b) Based on t between 4,4-diethylheptane and 4,4- dlethyl-1 -heptene and 1 -undecyne and undeC ane (c) 4,4-dlvlnyl-1 ,6 -heg^adiene had an index of refrac- distillation of eight carbon fraction (REDUCED BY SODIUM IN LIQUID AMMONIA) FROM ALLYL CHLORIDE AND SODIUM ACETYLIDE RESIDUE 125 14 300 FIGURE III So 1 4 2 0 0 115 40 50 60 % CHARGE DISTILLED tion much lower than predicted. After purification, the yields for the various hydro carbons isolated are listed below. Hydrocarbon Grams % crude charge 2 -pentene 49*7 2.1 hexsnes 64*1 5*3 3 -sthylhexenee 315*0 26.3 4-ethylnyl-4-vinyl-1 ,6 -heptadiene 158.7 13.2 The overall yield of the desired 4-ethynyl-4-vinyl- 1 ,6 -heptadiene was 6 .8/ of theory based on allyl chloride. The material (107 grams) boiling above the eleven carbon fraction on redistillation had a very wide 20 boiling point range (b.p. 62.5 - 30.0/9 mm, n a 1.4480 - 1.4532, d^°0.7533) Discussion; The only additional information gained from the larger runs was a verification that some allyl chloride self- c indorsation was occurring. It was reported by Stemfeld and ICharasch (33) that halides of weakly electronegative radicals will condense when treated with sodamlde in liquid ammonia if there is a hydrogen atom on the carbon atom to which the halogen atom is attached. Furthermore, they reported a large proportion of high boiling material in addition to a 10/ yield of 1,3»5**hex&triene when allyl chloride was added to sodamlde* Dimerization of the hexatriene would give rise to a twelve carbon fraction ;*hich may be present in the material boiling above the desired eleven carbon fraction. -85- The portion boiling above the eleven carbon fraction ,c not analysed. Its behavior on distillation indicated very complex mixture from which little information could ascertained* Sxperlment 4; Absence of sodium amide Sodium acetylide (6 moles) was prepared as pre viously described in five liters of ammonia. Allyl chloride (612 grans, 3.0 moles) was added dropwise with a vigorous reaction ensuing as if sodomide were present. Acetylone was liberated from the very start but dlmin- * shed decidedly as did the reaction itself after 80,1 of the chloride had been added. The reaction mixture was quenched with ammonium chloride and diluted with water. Steam distillation of the organic material yielded 370 grams (72;' based on allyl chloride). Fractionation yielded: at 1 146.5 43.2 - 46.5 1.4288 - 1.4351 39.6 at 2 1 ^7.0 24-23 /8 mm 1.4850-1.4940 44.1 t 3 15.9 52-55 /8 mm 1.4661-1.4647 4.3 Flat 1 was predominately unreacted allyl chloride with some conjugated material present as an impurity. A 30 gram sample was added to 4 gram atoms of magnesium in n-butyl ether. The resulting Grignard reagent was hydrolysed with a minimal amount of water. The ether 36- 1 ~yer had a light yellow layer after recovery In the usual way. On fractionation at 5-3 plates efficiency, only 2.2 grams wan recovered boiling below JcP C; however, aone material war lost in polymerisation by-aroducts as indicated by the color of the ether* The crude recovered had a relatively low index (1.4357)* The experiment was declared primarily to separate allyl chloride from any 1 -ponten-4-yne which might bo precort; howev,-r, the small amount of hydrocarbon recovered, and the fact the eight carbon fraction was highly conjugated indicate that very little, if any, .l-penten-4-yne was formed. Flat 2 w"s redistilled under reduced pressure to yield 100 prams (6l.4> of charye) as a constant boiling mixture (b.p. 35.0°/l7mm, n^P 1.4925 - 1.4234, S? 0.3044). It was halcyon free as indicated by a negative Beilstein and sodium fusion tests; however, it wave a Aight yellow precipitate with ammonlcal cuprous chloride which Indicated the presence of some 1-alkyne. Its Infrared spectrum suggested the pi'esence of an «( olefin bond, an acetylonic bond, type III olefin and terminal methyl group; however, the lack of any suitable reference spectra made it difficult to interpret the spectrum with any de cree of certainty because of the shift of the character- i Istlc absorption bands due to conjugation* The sample colored Immediately on standing and peroxidised very -87- readily. A 25 pram sample, uhen reduced by sodium and ammonium sulfate In lipuid ammonia, yielded 1 2 . 1 proms of the mixture of 3 -ethylhenenes • PI 0.1;' 3 red5.stilled under nr orsure "to five 20 1 0 , 1 prone (b.o. , 4° - 43.0/7him: n a 1.4637 - 1.4642) (",1.6 based on trie theoretical uiount, 2 nolee) of 4 -othyryl -4-vinpl -1 ,6 -hootadlone. p-’ oc11 r r 1 on : The reaction of allyl chloride and sodium :■ eetylido proceed'””* vi porously and in s t ant an e ou cl y vlthout - Introduction of any sodemide. The excess allyl chloride •;r.r I? soless and only hindered the recover’,' of products. An e::cors of the chloride *ras used In the hope th. t the five — c rhon fr-ctlon zrould be fozr:ed pr-eferontlally. The reaction •f'rji i otrod t";o s'^’’e o.ri't* c ’T e.s Z'he orevlous oezoorl1 'eu't s j hou— <-1-r--i■'-» - f ,r. "’it c r v>h ■Cr-'C ■- l o r ’-r’d ^ rf * "'’t"! ’' I T .'“h ^ - r b o l l l n ^ ^ ^ ^ ^ v-”* ~ ^ v*' a ^ ^ ^ ^ -r* <7 r'1 o r^ c on z u on — hi on7 , and there t -n a lozrer t’’■lo"1 d of the a?, even carbon fraction. The results of this experiment are compared zrith '•heso obtained by Lespleau and Joumaud: Reaction product so f sodium acetplldo and allvl chloride i b.n. C d 26-23 / 1 8mm 0 .7 9 2 3 1.4854-1. 4393 u i t h I-:aITK2 : (a) 3 1 - 3 2 / 1 3mm 0 . 3 0 4 4 1.4925-1.4934 u i t h o u tl!alTH2 H 2 9 - 3 0 / 1 6mm 0.7949 1.477 -1.490 tt L&J C-ll 52/ 18mm c.ai?7 1 . 4644 v;lth ire.H*2 (a) 3 2 /l3 m m 0.8176 1 .4 6 4 4 u ltht* o u t ITrdh ip 4o/2Cmn 0 . 8 1 9 1 .4 7 2 L&J (a) Present research. Experiment 6: Use of Lithium acetylide In Liquid. Ammonia. Lithium amid© (1 mole) was prepared from 7.0 grams (1.0 gram atom) of sodium and 1.5 liters of ammonia according to the usual procedure for sodium acetylide. Gaseous acetylene, purified a© before, was introduced below the surface. Acetylene addition was continued until the gray lithium amide suspension- solutlon was converted to the acetylide, at which roint the solution appeared blaelc due to the colloidal iron catalyst. Allyl chloride (77.grams, 1.0 moles) was added in 3 minutes but this resulted in a reaction of moderate rate which continued for an hour before the reflux diminished. Ammonium chloride waE added to quench the reaction and the organic material recovered as usual* Steam distillation gave 54 grams (o2 $ ) of 20 crude product (n^ 1*4727). The crude was stripped at low efficiency to give 22 grams of material (b.p* 45 - 46°C, nIP 1*4334 - 1.4354) which was a mixture identical to that obtained with sodium acetylide and allyl chloride* It had a slightly higher index of refraction and probably contains a higher concentration of the conjugated five carbon material, but it was predominately ally chloride* The remainder was fractionated under reduced pressure at approximately 2-3 plates efficiency to yield 15*6 grams 2 0 (b.p* 28-32 /17» nd 1*4844 - 1*4922 of the eight carbon -89- fraction obtained previously. However, there was no eleven carbon fraction present. Discussion; Lithium acetylide reacted with allyl chloride in the same manner as sodium acetylide. The initial con densation reaction was more moderate, but further allyla tion occurred on the resulting methylene carbon giving a net result similar to those seen in the reactions involving sodium amide. C. Experimental and Discussion of l-Heoten-4-vne 1. Preparation Experiment It Unsuccessful Attempt at Using Ethy Tma.conoa 1 ua Chloride. Magnesium (36.5 grams, 1.50 moles) shavings were covered with ether in a 5-liter, 3-neck flask equipped as usual. The reaction was seeded with ethyl bromide and, once started, an additional 750 cc. of ether was added. Gaseous ethyl chloride was added beneath the surface of the ether at a rate which maintained a good ether reflux. When the reflux diminished, the mixture was heated to reflux by a hot water bath for one hour* The mixture titrated 1.4 moles, 93*3^ or theoretical. The water-cooled condenser was replaced by a Drylce- cooled condenser. Gaseous 1-butyne (73*6 grains, 1.4 moles) , which had been prepared in 8lj£ yield from the condensation of sodium acetylide and ethyl bromide in liquid ammonia was bubbled in beneath the surface of the reaction mixture. Upon the addition of 1-butyne, which required one and three fourths hour, the reac tion mixture changed in color from black to gray with no gas evolution, and furthermore, it became progressively more viscous, necessitating an additional 500 cc. of ether to keep it fluid. Sven though the mixture was heated to reflux and stirred overnight, there was no apparent change in its color or consistency* To bring about the condensation of an acetylenic Grignard reagent with allyl halides, the procedure, as reported by Danehy, Killian, and Nieuwland (42), of using cuprous or cupric salts as catalyst was adopted* Pulverized anhydrous cuprous chloride (2.0 grams) was added to the reaction mixture followed by the dropwise addition of allyl chloride (107*1 grams, 1*40 moles) diluted in an equal volume of ether* Since there was no perceptible reaction upon the addition of the chloride, the mixture was stirred at reflux temperature for an additional five hours* After cooling, the reaction mixture was hydrolyzed by adding only enough water (approximately 100 cc of water per mole of Orignard reagent) to cause the magnesium salts to form small, hard curds, with the ether layer separating crystal t clear* The ether layer was stripped on a low tempera ture column to yield unreacted 1-butyne (63*5 grams, 84.0^) and 5*2 grams of redistillable 1-butyne. The 1-pentene formed was not determined precisely, because on the first distillation It formed a near constant boiling mixture with the large excess of ether. Redistillation yielded 48.0 grams (49^) of 1-pentene. The residue, after ether stripping, amounted to only 28 grams, and when distilled at 8-10 plates efficiency, yielded no discernible flat (b.p. 93*0 - 107.0, n^P 1.4177 - 1.4361) , nearly 30ft, lost as polymeric residues. Discussion; A review of the literature did not disclose any previous attempt to utilize Grignard reagents prepared from aliphatic chlorides in this type of reaction with 1-butyne at the reflux temperature of ether, whereas ethylnagneaium bromide, in which case the weakly negative anion remains the c?ne, gave a. good yield. Prom this result, it can be post ulated that ethylmagneeium chloride is too weak a base in comparison to the corresponding bromide derivative, because of the greater electron^Sfctlvity of the chloride ion. Rven though the metathetic reaction did not occur, a coordinated complex was formed. This was in evidence since no gas(ethane expected)was evolved on addition of the 1- butyne, and, furthermore, the reflux temperature of the re action mixture was the boiling point of ether. The change in color and consistency of the mixture was further evidence. However, the formed complex was destroyed on the addition ef -92 ■'llyl chloride since the 1 -butyne was regenerated and a ;h:rta-type condensation occurred to produce l-nentene. Experiment 2; Successful Attempt usinv Ethvl- Maareslum Bromide. The G-rignard reagent of ethyl bromide was pre- nared by the conventional procedure from magnesium turnings (43*6 grams, 2.0 moles) in ether. After stirring for an hour at reflux temperature, the Dry Ice-cooled condenser was substituted for the water- cooled condenser and 97.2 grams (1*8 moles) of 1- butyne was bubbled underneath the surface of the mix ture over a two hour period. The metathetic reaction was verv slow at the boilin'- point of 1-butane, and V ■w1 — t>’ f stirring had to be • continued for an additional five hour: The reaction mixture turned clear at this time, only a tnce of unreacted magnesium being present. After the reaction mixture was cooled to room temperature, 2.2 grams of anhydrous cuprous chloride was added. Allyl bromide (242*0 grams, 2.0 moles), diluted with an equal volume of ether, was added dropwlse. When the addition was complete, separation into two layers had occurred, and a large amount of yellowish-green flocculent solid had precipitated. The mixture was refluxed on a steam bath for an hour, then hydrolyzed with the minimal amount of water to cause curding of the magnesium salts* -93 The organic layer was separated, washed with water, and dried through sodium sulfate* The ether layer was stripped, yielding 10*0 grams (0*2 moles) (b*p., 8°-*10°C) of 1-butyne. Vacuum distillation at about 5 plate efficiency yielded 105 grams (70*0®?) (b.p., 47*5 - 43*5°C/79mm.; ni? , 1.14370 - 1*4370) of l-hepten-4-yne. This material was redistilled at 15-20 plates efficiency o to give 94 grams boiling over a 0.05 C range* Physical properties were talien and are listed below* 1-Henten -4vne This work Predicted0, (sup.) °C ... -119.02 v °C/760mm 109.34 - 109.88 102*3 0.7658 1.4370 1.4306 MR found 32.09 MR calc 32.06 CH found CK calc (a) Predicted from 3-hexyne and 1-heptene difference from n-pentane. The purity of the product was thought to be good, even thou^i it was impossible to get a significant freezing curve because of extreme super-cooling. The melting point was determined, but it was not possible to calculate the purity from this. The most likely impurities are those which would arise from conjuga tion or allene formation which were not evident in ultra violet or Infrared spectra, respectively* The found molecular refraction agreed quite favorably with that calculated. Discussion; Ethylmagnesium bromide with 1-butyne gave the metathetic reaction product in good yield, but the reaction was v e r y slow at t h e boiling point of 1-butyne. The most significant observation of this preparation is the boiling p o in t of l-hepten-4-yne. By utilizing the procedure out- lirted by Boord (54) for the prediction of boiling point and refractive index of an unknown hydrocarbon, l-hepten-4-yne was expected to have the following properties (b.p. 103°, n'S 1.4306). The boiling point found is 7*5 higher and is b e y o n d the experimental error usually encountered by this m e th o d of predicting properties. Properties of other re ported aliphatic 1,4 enynee were reviewed in order to determine whether there is a constant addition increment for such com pounds, or if l-hepten-4-yne is anomalous in this respect. -95 'laosrison of Pr orsrt io 20 foC/?60:nin r. rT Hsforence A -t *-Anpyy^20 1.4232 ^ )T» *?■ ^ .00 "4 T J-.0 7 '*»r»:. .-.i-O ~. \ — ■'■ ' - - \ M T 4 -• orer~4~‘a;e ’’-0-132 1.442c Predicted 6-3° - .0013 133 1.44-13 ::iouvlrr.c.(42) " -3o--t^.-;~4-,'rno 102.0 1.4006 Predicted 7.3 " .0064 ' 103.2 1.4370 This rorl; Oho ''roporti^r: o. 1 -o c t on-4-yno and tV.c- or*op untie c. of tie corrcoun&r. need for ^redictiri its prooortloe are v a r” reli able ; however, In tie c~ so of 1 -r on on -4 -y n o the r :■?.■* '-oilit:' is only fair. However, thie indicates that f * properties of 1 -hepten-4-yne are con sis tout *,rith thorc of its honoloaues and that there must he an addi tive ireraneat considered in tho prediction of enyne pro perties. To the Imowledye of the author, this additive increment has not been previously recognised* -96- Additional Sxner intents; Various Alkyl Halides and Various Conditions- Since an additional amount of l-hepten-4-yne was necessary, nine additional experiments were made utilizing the same procedure essentially as described above; however, the variables included alkyl halide from which original Grlgnard reagent was prepared, allyl bromide versus allyl chloride and stirring times* 1-Butyne was used throughout. A summary of these experiments are given in Table I. -97 * . * - * i Nn •a | 2 O 0 4 « O CM cm ■o to O. 1 _ _ • • • • • • • • O O O ^ tN - sotO s C7>to E $ S J,'3, ll 10 * 1 0 ^ SO so tO r-4 H H H o 3to -3 i u h h H l l a* h $ I H? s s i e e o o i 2 II ft tl A It ■ It K H H H £££££££ £ £ £ £ - fc§ JUS •» to O c o t o 1 1 1 ten-4-yne footer* Preparation Influencing tho of 1-Hep ti 1 1 ! 1 1 1 1 i ! i ; a a I -98- Discussion: Acetylenic G-rignard reagents are less re active than alkyl or aryl magnesium bromides in compari son to their ability to condense with bensonitrile (55)• The use of cuprous chloride as catalyst promotes the reaction with unsaturated halides, but is not as effective in increasing the yield if condensation, which is very poor, with saturated halides (56). From this study, allyl chloride gave only fair yields which corresponds with the only other reported use (5) of allyl chloride in the presence of cuprous chloride. Allyl chloride condensation with alkynylmagnesium bromide is a very slow reaction as evidenced by the increase in yield with a x longer reaction time, and is of less synthetic value than allyl Oromi&e. The preparation of butynyl Grignard reagent by a netathetic reaction between 1-butyne and alkylmagnesium halide is dependent more on the halide than on the alkyl radical. From this study, ethyl bromide is the most desirable alkyl halide because a gas is evolved so that the course of the reaction is easily followed, even though a Dry Ice-cooled condenser is used in order to retain the 1-butyne. In the case of n-propyl and n-butyl bromides, the gas evolved was condensed and returned to the re action mixture, thereby lowering the temperature with the result that a longer reaction time was necessary. When -99- working with alamos above 1 -butyne, ethyl, propyl, or butyl bromide would be suitable. Methyl iodide G-rignard reap-ent reacted Taster than methyl bromide, as Judged by methane liberation, but it did not go to completion, this being evidenced by the presence of unreacted butyne* On Eubsequent condensation of the acetylene Grignard reagent with allyl chloride, however a higher yield was obtained than with ethyl bromide Grignard reagent and in a shorter time. Therefore, it would appear that methyl iodide is superior to methyl bromide and on a par with ethyl bro mide, which is in fair agreement with the results of Tehao (8 7 ). It was possible to shorten the reaction time in the metathetic reaction by putting the system under -J* to 3/4- atmosphere of pressure (in the case of ethyl bromide, ethane pressure)* A trap filled with enough mercury to maintain the desired pressure and a capillary exhaust valve were installed beyond the condenser* By regulating the exit" of the off gas, it was possible to maintain a fairly constant head of pressure, and thereby increase the solubility of 1-butyne in ether* This scheme is unnecessary with higher molecular weight alhynes in as much as they are less volatile and are more soluble in ether* 100- 2. Hydrocarbons from llonomethylation of 1-heptsn-4-yne l-Hepten-4-yne (151*0 grams, 1*50 moles) was added over a period of three minutes to freshly prepared sodium amide (48*5 grams, 1.50 moles) In 3 liters of liquid ammonia* Formation of the dark red salt was instantaneous, but less exothermic than in the case of 1,4-pentadiene. The reaction mixture •was allowed to stir five minutes before methyl iodide (213*0 grams, 1*50 moles) was added over approximately two minutes, or as fast as mechanically possible* A violent reaction ensued, which ended with the addition of methyl iodide* Ammonium chloride was added Immediately and diluted with 2 liters of water* The organic material was fractionated, somewhat, during steam distillation because 110 rrams (ca.70/£) was readily distilled, whereas 17 grams (ca 11^), yellowish In color, with a high refractive Index (n^P 1*4717) came over at a ratio of 5 parts water to i 1 part organic material and 21 grams (13^) was non- steam distillable* On vacuum distillation, at about 5 plates efficiency, 52 grams (49*1 f*) of the material boiled over at 1°C range (52.0 - 53*0°C/62mm; n3P 1.4510 - 1*4533? oolorecj); however, this material was not one compound, but a mixture as shown by -101- redlstillatlon at high efficiency* The properties of this mixture alonr with infrared and ultraviolet absorption spectra before redistillation indicated that 1-hepten—3-yne was the predominant impurity* Furthermore, in the study of dimethylation of l-hepten-4-yne, 28^ was recovered as a monoolefin on reduction by sodium, which further su^ests that 1-her?ten-4-yne was rearranged in the presence of sodium -amide* The heat and time necessary for ■atmospheric distillation at 15-20 plates efficiency of 47 grams was great enough to cause the majority of the conjugated material to polymerize. Some of the desired product was probably lost by copolymer ization, but it was possible to isolate 20.1 grams (43/0 o f material which boiled over 0.5°C range (121.5 - 122.0°C, n?P 1.4393 - 1.4416). This material was added to molten malolc anhydride and stirred intermittently over a period of two hours. The unrescted hydrocarbon was stripped off through a Claieen head. Near the end, a total of 15 cc. of wcter was added dropwise to help distill out the product (with steam). The distillate was washed with water, and 507» glycerin followed by percolation through sodium sulfate. Distillation at 3-5 plate efficiency produced 16.7 grams of material identified as 3 -methyl- -102- 1 -lie p t en - 4 -yn e • 3 -Methyl -1 -hept en-4 -vne Thls work Predicted (a) P.p. (n.p.)°C glass b.p. °c/760mm 121.80 - 121.85 121.6 c tP 0.7670 n |° 1.4393 - 1.4396 1.4333 CH found CM calc MR found 37.04 HR calc 36.68 (a) Predicted from 3~heptyne and -1-heptene 3 -Methyl-1 -hepten-4-yne (5.1 gr- :r.s) was, hydro genated over 2"£ its weight of na.lla.dlum deooclted on barium sulfate catalyst at 28°C as previously des cribed. Fractionation at low efficiency yielded 3.8 gr-mc (b.p., 105.0 - 105.5? n%° 1.4246 - 1.4248; d^jjp 0.729-3) 3"raethyl-l,4 heptadiene. The physical properties agreed quite favorably v/ith those obtained in the alkylatIon experiments. The purity of the hydrocarbon was fairly good even though it would not freeze; the failure to freeze probably was due to residual conjugated impurities of which 1-hepten-3-yne and 2-hepten-4-yne thought to be the most likely. On the other hand, l-hepten-4-yne did not crystallize well, nor was it found possible to freeze 3 -methyl-1,4-pentadlene. The ultraviolet -103- spectrum was difficult to interpret because of lack of reference spectra; however, it was Judged not to indicate any conjugation in comparison to the known conjugated material. Futhermore, an infrared spectrum Identified only. The terminal olefin the carbon skeleton was proved by hydrogenating 12.0 grams of 3 -methyl-l-hepten-4-yne over 4.Q% its weight of U.O.F. nickel catalyst; the hydrogenate was distilled at 10-12 plates efficiency to give a 78/* yield of 3- rnethyiheptane. -104 DISTILLAT 10# OF LO* BOILING PROOUCTS FROM MCTHYLATION OF I-HEPTEN-4-YNE I * RESIDUE m i sN X IV FIGURE M' ? CHj CH2C=C-CH-CH=CH ch 3 Y* i 1.4450 s 3 I 1.4400 % CHARGE DISTILLED 5 -Methvlhentane This work Literature “ 122.1 - 121.2 118.6 - 119.0 119.1 0.7061 0.7055 1.3988 1.3988 The material boiling above the first flat was -predominately a mixture with boiling point and refractive index rising gradually with each sue- ceeding fraction (b.p. 49*5 - 65°C/45mm, n^P 1.4554 1.4628) to another small flat (b.p. 39.0/13mm or l60oC/760mm, n?0 , 1.4667 - 1.4675). All of the fractions were bulked and combined with the high index material recovered on steam distillation. A 50.0 gram sample was added dropwise to sodium (46.0 gramB, 2.0 moles) in 3 liters of liquid ammonia* After stirring for an hour and a half, the blue color of sodium still persisted and required 11*6 grams (0.145 moles) of sodium nitrate in "back titration" to react with it. Ammonium chloride (109.0 grams, 2.0 moles) was used to quench the reaction. The organic material was steam distilled, washed and dried to yield 39*6 grams (n^P 1*4207). The non-steam dis till able residue, approximately 9 grams, was a yellow, waxy material. On distillation at 15-20 plates the - 1 0 6 - SOILING POINT, * 0 /7 9 0 m m 129 120 RDCD Y OtM N IUD AMMONIA) LIQUID(REDUCED BY SOOtUM n IN tio istilla d FRO* METHYLATI0N OF I - HEPTYN-4- YNE HEPTYN-4- - I OF METHYLATI0N FRO* of CHARGE% OtSDLLEO gher h ig h boiling material 1.4150 1.4175 wo FIGURE steam distillate produced only one flat, exclusive of small head and tail cuts, that boiled within the range of cis and trans 3-methyl-3-heptene and cis and trans 3-methyl-2-heptene. There was no higher boiling product, this indicating the complete failure of dimethylatlon. Properties were taken on the com posite and are listed below. Properties of 3 -Methyl-2- and 3 -Methyl-3-heotene mixture Literature(85) This work 3-Methyl-2^ 3 -Methyl-3 heptene heptene F.P*(m,n)°C ------H.p°C/760mm 121.43 - 122.69 122.2 - 122.8 121.1 0.7318 0*7304 0.7280 1.4175 1.4180 1.4197 A 20 gram sample of the composite was hydro genated ovdr 5% its weight of U.O.P. nickel at 85°C. The hydrogenate was filtered of catalyst and treated with aqueous potassium permanganate for four hours at room temperature. Fractionation at 10-12 plates efficiency yielded 66.3/^ of 3-methylheptsne* The low yield was due to a mechanical loss during distillation. Discussion: Utilizing the procedures found the most suitable for 1,4-pentadiene, monomethylation of 1-hepten- 4-yne yielded 10,3h> (based on theoretical) of 3 -methyl- 1-hepten-4-yne and none of the dimethylated product. If the close boiling-, impurities which were destroyed during distillation were primarily l-hepten-3-yne, then approxi mately 2 5-30 of the latter was present. This would be the predicted impurity since triple bond rearrangement ^own the chain is favored greatly by the Influence of rodd urn amide accoring to the work of I-liller (57) and others (56) (59)* The substitution of an alkyl group for the acetylenic hydrogen apparently decreased the stabilization of the 2,4 enyne system, 1-Hepten-4-yne is more apt to undergo rearrangement than l-hexen-4-yne or 1-penten-4-yne because the triple bond is essentially in the number three position, whereas, a triple bond in the number one or two position is \ more stable under the influence of sodium amide (57)* This is in evidence by the high yield of material assumed to be l-hepten-3-yne in comparison to the rearranged l-penten-4-yne, Furtheroiore, the amount of rearrangement of 1,4-hertadiene was of the same order of magnitude which indicates 1,4 diene migrate Just as readily in contact with liquid ammonia. However, no strict analogies can be made because the degree of polymerization varies so much from run to run in these unsaturated systems containing such liable hydrogens. The material boiling above the observed flat (approximately 30% of the leolable material) was definitely a mixture of the conjugated isomers resulting from the rearrangement of 3~methyl-hepten-4-yne because on reduc tion b~r sodium in licmid ammonia it rave a mixture of J-uethylhoptenes. The amount of sodium consumed indi- a tod that 1•or bonds (92*3%) was reduced. This is within experimental error of two theoretical bonds if the material lost in ^olymerination is t alien into consideration. Since, hydrogenation rave only 3-methylhentane, methylation occurred only in the secondary position. 3. Attempted Dimethylation of l-hepten-4-yne In two liters of liquid ammonia was prepared 1*0 moles of «odium amide. l-Hepten-4yne (0.5 moles, 47,0 prams) •.as added rapidly folloired by the addition of methyl iodide (l.0 moles, 142.0 grams) over a five minute period. The reaction subsided immediately and was quenched with a saturated ammonium chloride solution. The organic layer was separated manually, washed with 2% sulfuric acid, dilute sodium bicarbonate and 50 p glycerin before drying through sodium sulfate to yield 4l*l grams (n^P 1*4458). The Interface material was steam distilled to yield 4.6 (nlP 1.4457). This material was composited (45*7 grams, 75*0% based on theoretical yield of dimethylation) end reduced by 36.8 grams of sodium In two liters of 37.3 Yield (oharge) > % of original ofalkylated Rocor- Yield (oharge) SSARBlXQaiBliT SSARBlXQaiBliT BBABBAMGEKBSI % XAB1K n Yield (theory) % leeulta Alkylationof of 1.4Oneaturatec Ho l d (theory) MUWOAUnfLATIOH MUWOAUnfLATIOH % UtaotttRearrangement PIAlJTUTlQM flneaturate 1.4 1.4 tbaaturate ery Xaeledesdiuethylated eaterlal* Crude reducedby •odiumand liquid aasonia. Determinede. frea hydrogenated product I Muethylatian — 12.8 3 50.1* 78.1 Diallylatioa 4*0 8.8 2 40.8 66.3° Hottnethylatiou 21.0 7.6* 6 38. Ob 91.3 Ddaethylation — 2-3 27.9 32.8 78.0 Moaoaethyiatlea 9*8 trace 25*30 54.2 89.1 Meaeallylatiaa 13.7 — — — IHaethylatMa — trace 31.2 44.0 53.8° XBBoacthylatiai 10.3 traoe 25*30 50.9 72.2 S&allylatiea — 6.8 2.1 28.3 63.9® 1*4 t M S i m i X k 1,4-FDZIDin If4-*P1JDIM l-P*ftnS-4-U S Ill- liquid cmr-onia. Prr.ctionc.tlon of 40.5 prams at 13-20 -•I-too efficiency yielded 11,3 grams (27*9;*) (b.p. , 53.6 - 95.0°C; n 2 i 01 ecuscion: The optimum conditions for dimethylation of 1,4-rentadiene were inoperative for dimethylationcf 1-hepten-4-yne. The 2Sp yield of the monohentene, result ing from 1 -hotter-4-yne, in contrast to 1,3-pentadiene is further evidence of facile triple bond migration down the c;iain. Discussion of Results: Alkylation of Aliphatic 1,4- unsaturated systems. The hydrocarbons containing a methylene grouo activated - 112 - ' md j ncent triple or doubl a bonds are more acidic th.cn ■cotvlano. They are netalnted by sodium amide or sodium ••.cetylide in liquid ammonia. by replacement of an acidic hydro yen of the methylene group. The resulting organo '"odium compounds may undergo rearrangement under the basic conditions, with the formation of conjugated isomeric compounds vhich are immediately amnonolyzed because ammonia is a relatively stronger acid than the conjugate acid of the revly formed hydrocarbon compound. The rate of rearrange- rz-r.t is apparently dependent upon the symmetry of the miion, Eince 1 f4-pentadiene and l-penten-4-yne undergo little rearrangement, whereas substitution of a hydrocarbon atom by an alkyl group in either the primary or secondary ^ocition (as in 3 -methyl-X,4-pentadiene or 1,4-hentadiene) rearrange very readily* The electro-positive character of t the alkyl group is great enough to enable the electrons to migrate to a preferred orientation, l*e* that of the conjugated isomer, at a faster rate. (Refer Morton - anion accepts position of least alkylation). -113- ATTSI-'PTZD PREPARATION OP 1 ^-FSHTADIXNE A. Historical and General The 1,4-diynen have received less attention than the corresponding dienes or enynes. However, 1.4-pentadiyne was particularly desired to complete the series of terminal 1,4 unsaturated aliphatic derivative. Ho general method of preparation is available, but the use of cuprous chloride as catalyst would undoubtedly promote the reaction of propargyl bromide with acetylenic Grignard reagents as it does for allyl bromide (42); therefore this was the method used In this work. Tchao (60) was unable to react alkylpropargyl bromides with an alkynyl- magnesium bromide without a catlyst even on boiling for six hours In toluene. He found, however, that substituted propargyl bromides and alkynyl sodium would react at l40°C in toluene to give 15-20^ yield of the desired 1,4 diyne. Since 80-90^ of the bromo compounds reacted, it has been proposed (6l) that the by-products Included trl- and tetra- acetylenes resulting from metalatlon and alkylation of the central methylene group of the 1,4 diyne first formed. Grignard and Lapayre (39) prepared 1,5-diphenyl- 1.4-pentadiyne in Qfo yield by heating methylene -114- iodide with, phenylethynylmagnesium bromide. They determined the relative acidity by the same series of reactions used for 1,4 enynes; they found: sodium reacted slowly with the hydrocarbon; sodium amide in toluene liberated ammonia from it very slowly; and the reaction with, ethylmagnesium bromide was 9 3 % complete at 35° for one active hydrogen and at 80° was 90% complete for two active hydrogens. They concluded that 1,4 diynes possessed more active hydrogen, than 1,4 enynes but they, recognized that the presence of the phenyl groups could help activate the methylene hydrogen. Jozitsch (63) (64) reported the preparation of the dimagpiesium derivative of acetylene by the reaction of the gaseous hydrocarbon on the Grignard * reagents prepared from numerous alkyl iodides and bromides, and from tertiary-butyl and benzyl chlorides. Other workers (65) (66) obtained similar results and the dimagnesium derivative has been used to prepare dl-substituted derivatives of acetylene (67). Zal*kind and Rosenfeld (68) and others (69) (7*0) (71) (46) claimed the preparation of the monoderivative by passing acetylene Into the ether during preparation of the Grignard reagent. They concluded that the monoderivative was formed first and that the reaction could be stopped at this stage. 11) G ^ J Ig B r ♦ BCSGE — ^ HC* CMgBr iS) S m m tm g B r -- * BrMsCsCMgBr ♦ HC«CH Grignard, Lapayre, and Teheoufaki (40) (62) claimed yields of the monoderivative as high as 80-90^, tout thought the derivative was first formed and then the equilibrium (equation 2) was forced to the right toy an added pressure of one-half at mosphere of acetylene. Teheoufaki (62) believed that yields approaching theoretical could toe achieved toy greater pressure* They determined the proportions of mono- to di-magnesium derivatives toy cartoonation of the mixtures to propiolic and acetylenedicarboxyllc acid, but also reported the preparation of 3 -phenylpropyne in 7 0 f j yield from benzyl bromide and the acetylenlc Grignard reagent* Desaturation of vicinal dibromoalkanes toy sodium amide in liquid ammonia to produce 1-alkynes was first reported by Nieuwland and coworkers (72); however, it was already known that 1-alkynes could toe prepared in good yield toy the dehydrohalogenation of suitable halides, such as: R-OHXCH2X, HCI^CHX2, RXgCiij, RCX^OHgand RCH»CHX, with sodium amide in an invert solvent or with ethanolic alkali (73) (59) (75)# Ethanolic alkali as the dehydrohalo genat ing -116- reagent has some tendency to promote a shift of the triple bond away from the end of the chain (76) (77) (73)* whereas the direction of rearrangement is reversed with sodium amide (57) (72). Gfood yields of 1-alkynes can generally be obtained because of the formation of the stable alkynylsodiums. Hiller (57) dehydrohalogenated straight chain vicinal 3,4-dihalides by sodium amide in liquid ammonia and found the reaction products had largely rearranged from the expected 3-alkynes to the corresponding 2-alkynee. V/hen he dehydrohalogenated 4,5-dihalides, they gave predominately the corres ponding 4-alkynes with a smaller amount of rearranged products. Since the Grignard reaction failed to produce any 1,4-pentadiyne an alternate procedure was tried. It was believed at the outset in llggvt of previous work that the best possibility of preparing a 1,4-dlyne by dehydrohalo genat ion would be 1,4- pentadiyne because of Its terminal acetylene groups. B. Experimental and Discussion of 1,4-Fentadiyne Experiment 1: Preparation of Acetvlenemono- mapnealura Halide, Run 1: The procedure adopted for the prepara tion of acetylenemonomagnesium bromide was patterned as closely as possible to that reported by Grignard et.al. (40)* However descriptions of the experimental conditions are very brief so that it is not possible to sa3’- that the concentrations and other pertinent re action conditions used here were actually the same. The resulting Grignard reagent was reacted with acetone in order to determine the success of the reaction. Ethyl bromide (0.52 moles, 57*0 grams) and magnesium (0 . 5 2 gram atom, 12.6 grams) were used to prepare the Grignard reagent in one liter of ether. After stirring for an hour at the reflux temperature of ether, gaseous acetylenea was bubbled underneath the surface of the mixture. A precipitate, reddish in color, appeared after approximately one-half hour a. Purified by passage through a train consisting of two concentrated sulfuric scrubbers and a drying tower of calcium chloride and Drierite. -118- vith. a gradual change in colon of the entire mixture to a deep red. At this time, the system was put under one-half atmosphere of acetylene pressure and the mixture was stirred vigorously, With this pressure, the precipitate became tacky and formed little balls of material which ire re rolled about by the stirrer. At the surface of the mixture, a portion of the pre cipitate clung to the walls of the flask. When the acetylene oressure-was relieved, the precipitate resumed its original character, and, furthermore, whenever the stirring was discontinued, the precipi tate would settle out, leaving the etheral layer nearly colorless* Acetylene under one-half atmosphere of pressure was admitted for six hours with little or no apparent change in the reaction mixture. Dry acetone, (0*50 moles, 29.0 grams) diluted in an egua.l volume of ether, was added dropvise* An exothermic reaction occurred, but subsided greatly before the addition of acetone was completed. The mixture was -heated to reflux for an hour with a slignt evolution of acetylene. Following hydrolysls, the ether was stripped, leaving^p residue of 33.6 grams fractionation yielded 14.2 g or 37/* (b.p. 55*0/l04ram 1.4042 - 1.4058) and exclusive of a small intermediate cut, the remainder crystallised on cooling. -119- The material boilinr on the flat was identified, by comparison of its physical properties, as ter tiary amyl alcohol Instead of the desired dimethyl- ethynyl carbinol, The residue, on recrystallisation from ethanol and water, yielded 16,5 g of 2,5-dimethyl- 3-hexyne-2,5-diol (m,p* 93*6 - 94.3°c) PI acusalon: The reaction gave none of the desired acetylenlc rl.coh.ol. The reaction is peculiar in that the othylmagnesium bromide which underwent a netathetlc reaction with acetylene pave only the acetylenedimagnesium bromide, XTearly one- third of the ethylmagnesiun bromide, however, remained unroactod. Since It has been shown in this work that 1 -bu— tyne and ethylmagnesium bromide react rather slowly in the similar metathetic reaction, it was thought that perhaps Insufficient reaction! time had been orovlded for conBumo- * tier, of the original drignard reagent. Operating on the premise that the precipitate was en tirely the dimagnesiura derivative and that an equilibrium existed between the mono- and dl-magneBium derivatives, numerous experiments were conducted in an attempt to achieve conditions under which the equilibrium would favor the monoderivatlve. Assuming the monoderivative formed first, attempts were also made to stop the reaction at that stage by adding the condensing reactant before the precipi tate formed by use of high dilution, and by the inverse - 120 - dditlon procedure. Typical experiments are summarized in able ITT and brief experimental details are given for those hat differ from Hun 1. Runs 2.5 and 4: Identical to run 1 except dilution and stirring times. Runs 5 and 6: Gaseous acetylene was passed into one liter of boiling ether during the preparation of ethylmagnesium bromide. The pressure was maintained at one-half atmosphere by allo*/Ing the excess acetylene and liberated ethane to escape through a capillary leak controlled by a valve. Before the addition of ethyl bromide was finished, the formation of a semi-solid precipitate was evident. It behaved in a manner similar to that obtained In run 1. m u L i Ethyl ether replaced by dl-n-amyl ether in order to attain a higher reaction temperature* Run 8* Gaseous acetylene added over a one hour period to 650 ml of ether In a 2-liter flask which m e immersed in Dry-Ice acetone bath. Ethylmagnesium bromide (0.51 moles) prepared in a second flask was gradually transferred to the first over a hour period through a siphon aided by nitrogen pressure. The total volume was approximately one mole. Upon the addition of the Grignard reagent the mixture changed to a light cherry red. Acetylene addition under is atmosphere of pressure wae continued for an hour, then the mixture was warmed to room temperature, still under d atmosphere of acetylene pressure* At -70°, the precipitate was a fine, granular, white solid, but as the temperature rose, the ether became colorless and the precipitate acquired the characteris tic color and consistency as previously noted* Acetone wan added at room temperature and stirred d- hour before hydrolysis. In this and all experiments Involving a reaction product which might be soluble in water, the i reaction mixture was quenched with Just sufficient water to liberate the product and fora an Insoluble magnesium containing sludge. Some acetylene polymer apparently was formed since the products recovered amounted to 111*5 of theory* This was a duplication of run 8 except that acetone toe added at - 7 2 °G, and then the temperature was allowed to rise slowly to room temperature. The -122 reaction mixture behsvsd in much, the same manner an in run 8; however, the precipitate had lost its stichy character at -15° to -10°C. The clear etheral solution was separated from the fine, granular insoluble magnesium compounds and hydrolysed separ ately. The material (23.5.grams) recovered from the ether layer yielded 20*6 grams (72.3;3) of t-xnyl alcohol. The residue (2.3 grams) was mostly acetyl ene polymers since it would not crystallize. The material (13*3 grams, n^p 1.4-129) recovered from the nrecipitat© was lost mechanically before distillation, but in all probability, war the exnected diol and acetylene polymer. Run 10: Conditions identical to run 1. Run 11; Here the 8-rignard reagent was added to acetylene solution in diethyl "carbltol'1 at -70°. The behavior observed was similar to that observed in ether at low temperature. Before hydrolysis the reaction mixture was heated to 80° for three hours under 1 atmosphere of pressure. -123 s-. /-i * i c" ^ O V't t 1 %x •* . I - - , T f ■'«'"! t’*i*] ■••,"! Y~* q" ' <• v->^ •• • _**".-? • ,“' • i ^ v , "' - ’ * ■ : : J:hyl e::yra -P: , t-di ol o''.it. ' :* ra-1 in ticro ?x;'C'"inenL, frfluorcod moot, by the ler.'hh o.r th*. reaction tiro, " " - - Q "?J ~ ^ ™ ^ ^ ^ ^ * **■.*:■ i ' ^ t* - , * -» ** *--> - 1 + . * ■ ■ - t ■ ■ ^ ^ 1 * ^ J i -“a ^ *1 * 4 ~ , r ~ ~ ~ “ t >—*. ^ „ • f * i * t ^ ^ t t ^ 4 ^ 2*2 O if* t "~ ' ' " " -V' ^ *n *i a a"; *u fi .-"* '* J '1 .r ,f^ *.,..• x*. ... „ ., ^ .. ^ ^jlr y> *r* ^ ^■Tfr ' r-* Table H I , an increased tonperstur * - -v.' o i o * ’'"1 c r J '■•■t ^ i r. q; - Q* p**i • f-j- tuit - ' • - -t *■ • " - T ■••, ,", x ^ ^ ^ ,7 ^ 1 -» -—I -no 1 IrtV, *1 S’ , r- f“i f-> ^ **"* JTT. •*- ^ ^ f ■* , , X ' . • m „-~ ^ J. J _ 4.-» » . „ ■ - ' • W* « m • J- ■■' .A U V-- ^ T- Mi •--' ►.— • •-_ M ... k - ' t • i A ^ Apf1 .. . . 'W i. Si- -. »< ‘.^ M. ’ X A '-''O. i".:o proportion of tie tiro products rnav be inri’’.or.cod 7--.ad:r‘ acot;-dero .^rosr-'.re, codr'.nt, r.r.d oripinal C-ri pno.rd - -. 1 J- 'Ti~' -r‘ m, ' f* * r ^ i"*’ ” X * - ^ o o p + t ^ " T ■ "4 j£i r* r* t ^ *t '* jri r* -rp ^ 4* r*> ■* ^ '-•' ^ •* * ^ * r *' * •• ^ A -i ... . t.-»r kiJ 1 *'-4 A. %. J. . a .. - * • -. i V-f - .. raAr 1- d, - - - r - » •* " r ■ > , " > ^ ^ ' * ' - • ■ * • -i f-s " 1 ■* * ...'4.V. ••,•. i * 1 ^ 1 ■? r ^ ' •*' J' *»!»'*■<:“' ^ **1 x T-. J, - ^. . . . •-, ••-- a • ■ - . - J ■>- i i- • i ,U — - *.. a ■* ' • - W . t i. . u- w^.a._ v^- \ j I X V >- • - • ■ * ~ C * ^ *^: -.n ' ‘ r"| .-^ X,"1 "■ ^'*1n -p r-" ■■" * J- " ' - r- “J ^ X "1 ^ ^ 7-yp^ d.'? f.n orie? to obt^.ir. n bir":or rok .ction te:.rien“-.tnro. A '*re*-.ter v r i s t yr of solvents ’’s.s not used ooc'-uo otner "or':orr at tdir Univrclt;.r, ncmoly, Prof, Melvin M e m m and co'uo’r’iorc and Mr, Pr ul HinMaj^n, ’„e r e concurrently rrarl'inp on r s-v.'.o nr obi on, dlie Malido used to -^renaro tbe orir'in,al Iri"v•* rd r e s ' a ' t uas etburl bronido in ov .-up* c"se e:;cont n o ? n ubicM ethyl chloride oras used, Zt hy in a pme c ium chlor ide failed to react vith acetylene. It Is to be noted that ethylmnynesiuni chloride also failed to react vith 1-butyne, The experimental evidence obtained on the netathetic rc'ctions of l-hmtyne and a.cetylene ■'.rith ethylnaciiosiun - 124 - SX uaod DILUTION HC CH DisntLATiuu charge to f a m nalas par Tina Hold Jfc Yield > Bun HMgX iltar SOLTEK¥ REACTANT Stirring PRESS. t-Anyl OH oruda d i d MCMAEKfi 1 ItBr 0.6 St Sthar Aoatona ♦6 7 1/2 37.0 43.7 2 StBr 0.6 It Sthar Aoatona ♦24 7 1/2 20.6 68.0 8 StBr 0.6 It Sthar Aoatona ♦1/2 7 1/2 72.0 6Jt d ItBr 0.1 St Sthar Aoatona «6 7 1/2 23.7 88.2 mobanleal Io m add ad BC CH dor* 6 StBr 0.28 St Sthar Aoatona 2/4 hr. 7 1/2 72.7 13.6 lag foimtion of Grignard 8 ItBr 1.0 St Sthar Aoatona 48 7 1/2 12.5 61.9 7 StBr 0.6 n-Anyl It Aoatona 8 7 1/2 28.3 51.3 66*C. Addad aooteno at 8 StBr 0.6 St Sthar Aoatona 2 7 1/2 62.4 26.7 rooa to^>. lmraraa add'n of ItMgBr Addod aootono at 8 ItBr 0.48 St Sthar Aoatona a 7 1/2 72.3**) 2 6 - 3 o W -7Q*C. invar so 49.9 add'n of ItMgBr 10 StCl 1.0 St Sthar Aoatona 4 1/2 7 1/2 81.0 0 11 StBr 0.6 Aoatona 21 7 1/2 10 invar«e various oarbitol taqp. I*) Saapaga 122* run 9. TABU H I Sffaot of Conditions Ylold of DihalMKgneslunicstylan* ' -“"i" * " ^ ■** ^ ^ ^ * ~» 1?0 —> -'~'.r* • w i Xr ’ O^ £* do ■*■ 11 * * oA* ' ”0 T*03.^ ^'r ^ ■" - ”L■ vx fy j. j. V.. ,^-^ ^ i f1 f*^ c - 0 n ’t- G r ,0 r r*,'r J ronc^ io^' iio ^vh^-pp-y^i*— -p ■:’- ovorcono the unfavorable factorsIf solub llitv r.nd \ V -cl'If.llty, Solubility of the alhyr.e 3 n e t h e r alon-~ w i t h -l - - 1 --,-.v»- t'li'O of reaction ore vsrv in^ortrrt ac noted hv *.■ '■• r'il o ” thee of e t" "'^Ins.^—r c 2 iun bromide with 1 —'"*‘Grt,rr© (1 bn. -vt ; ’l°) and with that of l-bv.tyr.e (7 lire, at 20°). "b-.w r, n.one of the reported no tot hot ic al reactions of this + yo to completion* The failure for complete reaction — y Involve factors 0 1 0 0 1 0 than time because In till 0 vorli •'/'•ot.ylone v-"1 2 added to ethylnayne slate bromide over a 4.1 hour -'erlod under ’ o.taosohooo of pressure, and 2t3.ll 1 2 —15m *;aa ? r*ol" tod ".s tin reacted ^rirr.s.rd. reagent. . Thi s seems to ‘: f ’.c to the formation of complex -acetylene being liberated. hither the formation of a complex or the cl: la o f sufficient reaction time could explain the oreronce of the m h-hnl "rlynard reagent, but these cannot explain the co v -loto absence of the mono-derivative. The exact composi tion of the C-riynard reagents formed was never determined, but tho proportions of mono and di mere Judged from the reaction 'relucts obtained on condensation w ith acetone. There is the remote oossibility that the monoderivutlve, In the course of reaction w ith acetone, would undergo another m etathetlc reaction and, subsequently, yield the dlol or the product oxoected from the dimagneslum derivative. - 126 - o CH.-C-CH* ♦ HCVOUgBr * HC * C-C- (CH* )-dl«Br CH. CMfcBr GMcflr HCst C-C-CH* ♦ HC* CUgBr «—■* (CH*)*-C-C sCMgBr ♦ HD *CH (CH. )*-Cc*rC-M*Br ♦ C^-6-CH* — * (CH* )s-fc^mC-£(CHa)» Th5. s \rus not dleprovsd, but Is conc 1 clered h 1 rhly ir.orobr.ble because neither the acidity of the a l k y n y l h y d ro -a n nor the solubility ofthe condensed p r o d u c t should bo s i y n i fic rvntly different- fron -acetylene mono- n u r n eslum b r o n i i e . Furthermore, the m onohal on ayne s 1 ura acetylene -•Quid be expected to have been about as soluble -as the oriylnal alkyl C-riynard reayent* There is the possibility i ' v t th e mono-derivative niyht form an insoluble complex, but knowlodyo of other Grignard complexes indie cates that t h is is not very probable; therefore, the precipitate o b s e rv e d must have been the di-derivative* The nresence of unreacted ethylmagnesium bromide to-'other with acetylenedimagnesium bromide and excess acetylene, while, acetylenemonoraagnesium is completely absent (as judged from the obtained reaction products) appears to be contrary/ to the common belief that the equilibrium CoHg +• XMgC wm. Cl-IgpC 2HC WL CligX can be shifted to the riant* It could indicate, however, that the XMgC CMg% is formed directly, and that no equilibrium change, either right or left, is involved. Thus it would appear that the -127- hnlonagncciura rroup, upon replacing one hydrogen atom of acetylene, actually increases the replacement of the second hydrogen atom. Then, I f the dimagnesium derivative is co?ipletely insoluble in ether at the pressures used, tlwt would explain the app arently complete irreversibility o f the equilibrium previously postulated, T.7hen one hydrogen of acetylene 1ms been replaced by ?. substituent, the lability of the remaining hydrogen atom is Influenced, "When a phenyl group is substituted on water, on a c e t y le n e or on ammonia, it produces the sane qualita tiv e - effect on the lability of the remaining hydrogen atoms in t l w t phenol, phenyl acetylene and aniline have more labile h y d ro g e n atoms (7 9 ) than the parent compound. The introduc tion o f a haloraagnesium group may have the same effect, .and, thereby help to shift the equilibrium in equation (2) to th e left, 1 From this work, it would appear as if the earlier workers misinterpreted their low boiling product since the presence of an ethynyl group affects the boiling point about the seme amount as does that of an ethyl group, G-rignard and the other workers assayed their mixtures by carbonation, and they reported yields of propiolic acid as high as however, acetylenedicarboxylic acid is known to diearboxylate quite rapidly, and this makes it possible that they had only the dimagnesium derivative, after all. However, it is difficult to explain how they could have mist alien alkanes Tor 1-alkynes, e*g* n-hexane Tor 1-hexyne In the reaction of n-butyl bromide with the acetylenlc G-rlgna-rd reagent* In concluding this work, it was postulated that the persistence of unreacted ethylmagnesium bromide could be explained by insufficient reaction time or perhaps a com plex formation* The solubility of acetylene in ether is low so that considerable time was required for reaction and when reaction did occur to form the monoraagnesiura derivative reacted Immediately with another mole of Grignard reagent to yield an Insoluble dlmagnosium deriva tive. There Is also the possibility that the halomar- nesium group activates the remaining hydrogen, which, In conjunction with the Insolubility of the dimagnesium derivative, would make the proposed equilibrium effectively irreversible. It was difficult to conclude that previous workers had misinterpreted their data and that such a gross error had remained unchallenged in the literature, but from the new experimental evidence It appears that the only Grignard reagents present are; (1) unreacted original Grignard, and (2) acetylenedimagneslum bromide* Experiment 2 s Attempted Preparation from 1.4- Pentadlene* Bromine (960) grams, 6.0 moles) was added drop- wise to 1,4-pentadlene (204*0 grams, 3*0 moles) in -129- o 900 cc of methlcyclohexane at -10 to -20 C. The crude bromide was then added to sodium amide (11,8 moles) in five liters of liquid ammonia. Before tlie addi tion of the bromide was completed, a black, granular precipitate appeared and tended to cling to the stirrer shaft. Upon hydrolysis, the black precipitate appeared in the mothylcyclohexane layer and, on filtration, a near quantitative yield of a black, polymer like coffee grounds was obtained. The polymer, after washing with 2p sulfuric acid -and water gave a negative- Beilstein test for halogen and was soluble only in concentrated sulfuric acid. Run 2: The same- procedure was followed as in run 1 except on a 0.1 mole scale and debromination carried out at -75°C. Some results were obtained as at the boiling point of liquid ammonia. Pi emissiont In an attempted preparation of 1,4-pentadiyne from 1,4- pentadlene, only deep seated polymerisation resulted. -130 tlxuurlment 3 1 Attempted Preparation from Lithium Acetvllde In Tetrahydrofuran Tills exTieriraent was an attempt to find a proce dure that could ho adapted to the reaction of pro- pargyl bromide with sodium acetylide, which would produce 1,4-pentadiyne if secondary reactions failed to occur, Allyl bromide was uric because it is rol ■' tlvcly chsar, Lit h i urn am Id© w~ s pro ^ a re d from lithi urn (3*5 prams, 0,5 nolcc) and llguid mamcnla containing ferric chloride as a catalyst. ” ::ceat that it reacted more slowly, lithium behaved similarly to sodium. To con vert the lithium amide to acetylide gaseous acetylene wac added until the solution turned jet blach and the absorption of acetylene was negligible. After 90a of tha ammonia had been evaporated, tetrahydrof uran (400 cc) was added and the mixture 'heated with hot water to its boiling point for six hours to remove residual ammonia. Allyl bromide (61.0 grams, 0.5 mole) diluted in 50 cc of tetrahydrofuran w » e .added dropwisc to the gray emulsion of lithium acetylide, at ice water temperature. There was no visible reaction or evolution of gas, so the reaction mixture was warned. -131- - * *"*0 OI*"7 ^ '^1’''1 * + ’ *; -■" *\a---l r’^", 5 V**^ ^ f**' ^ ^ <■ lp v rl^ 4 ^ J.hern yy g olTt- inod 1020 cc of a £-as, oresumably acety lene ; however, there was littlo heat of reaction. The tetrahydrofuran layer, cherry red in color, was decanted from the solids, presumed to be rodium bromide. This layer, or distillat ion, had an initial boiliny T'oint of 59°C; the temperature then rose rapidly to 65° • Practically the entire charye distilled over ■ 9° r rr-e (65.C - 6 7 .O0 (uncorr.) , n%° 1.4039 - 1.4140), le-vlny a blach, oily residue. Ticcrcs.ion: Little reaction had occurred between allyl bro mide ani. lithium acetylide. Acetylene was liberated, and the distillate was primarily/ a vec& azeotrop© of unreacted allyl bromide and tetrahydrofuran • ITono of the do sired 1-nentene- ■ 4-yne or rearranged isomers was formed* The larye amount / of the residue Indicates that the methylene%r hydroyen \d r ..,- were aprarertly acidic enouyh to undergo a slow metatlietical reaction and be further allylated or that polymerization had o ecurred. The failure of the reaction to yo to completion may be for two reasons. First; organolithiun compounds are less r o l a r or reactive than organoso&ium compounds ( S i) and re q u ir e a lonper reaction time. For example, phenyietbynyl l i t h i u m with an excess of benzonitrile required a reaction -132- . i:.ic- of 60 'lours (^O) for th lithium compound to be ■j.r"1 uy, ’rhcrcas the sodium compound reacted in 6.C hours), fa-cond; lithium acetylide is almost insoluble in tetrahy drofuran, The latter determined to be 0.0016 rra.ic in 1.5701 grams (l.oA ml) or 0.00 grams in 100 cc of tetrahydrofuran. This solubility is slightly better than th- .t of sodium acetylide in organic solvents; 0-reonloe had fount sodium acetylide to bo completely insoluble in a urloty of organic solvents. -133 V. HB.'.CTTOITS OF CYCLOPTFTABIFFF \, !!i r.tori C - - . 1 and General Cyclopentadiene war described previous!;/ as being anomalous among the 1,4 dieres because the double bonds activating the methylene grouo are conjugated and, furthermore, are contained in a symmetrical planar ring v/hich enhances resonance stabilization of its anion. Because of the highly activated methylene hydrogen, cyclopentadiene is capable of condensing uith ketones and aldehydes in the presence of a baso to form ful- vones. Thiele (24), in 1900, successfully condensed acetone v/ith cyclopentadiene and an eouimolecular quantity of sodium ethylate in alcohol, and many modifications of this reaction have been developed since that time. The formed alcoholat© evidently re acts with £he excess ethyl alcohol to liberate the ful- vanol, v/hich then undergoes dehydration to fulvene be cause fulvanols have never been isolated in reactions involving alcohol as 1 the solvent. Grignard and Courtot (27) v/ere able to condense the Grignard reagent of cyclopentadiene (prepared by a metathetic reaction) v/ith ketones in ether and to isolate the corresponding fulvanols• More recently, Heed and Yost (88) prepared methyl ethyl fulvanol by adding 3 ,5-dibromocyclopentene to magnesium to form the monoeyelopentadienyl Grignard -134- percent which, was condensed with methyl ethyl ketone* They obtained 2-cyclopentylbutane and 2-cyclopentyl- 2-butanol upon hydrogenation of the reaction mixture, vrhich indicated that some of the tertiary alcohol had dehydrated to form the fulvene* In this work, an attempt was mad© to condense cyclopentadienylsodium with a ketone in liquid ammonia, and then isolate the fulvanol in a manner sililar to that used in the preparation of acetylenic alcohols from sodium acetylide and ketones in liquid ammonia; the latter process has been patented (Bp) (90). The most successful procedure used in recovery of products involves the following steps; (l) evaporat ing the ammonia from the sodium alcoholate; (2) ouench- ira the alcoholate with ammonium chloride, then evaporating the ammonia and dissolving the organic material in a suitable solvent. Liquid ammonia being weak enough an acid that the sodium derivatives of acetylenic alcohols are not decomposed, the sodium derivatives of dialkylfulvanols were expected to be stable. -135- An attempt was made to reduce the conjugated fulvunol sodium salt by sodium in liquid ammonia and then liberate- the cyclopentenyldialkylcarblnol. Unfortunately, the decree of* polymerization was so severe that it was impossible to accurately interpret the results, but apparently some chemical reduction of the alcohol had occurred. Chemical reduction of alcohols by means of sodium "ind potassium is generally impossible. However, some alcohols activated by double bonds or aromatic nuclei are reducible at room temperature or below (96) (97)• Klayes (91) reduced benzyl alcohol with sodium and ammonia, but obtained only partial reduction of dimethylphenylcurbinol. Birch (31) (92) (93) reduced a. number of phcnylsted carbinols and a few non-aro- matlc allyl alcohols with sodium in liquid ammonia when an alcohol was added as a oroton donor. The reduc tions of aliphatic alcohols successfully performed weret 1-vinyl-1-cyclohexanol ethylideneeyelohexane; sabinol to sabiner.e; and peranyl methyl ether to geraniolene* These alcohols all being: ally lie, Birch postulated th© formation of a mesomerlc anion c=^cj - which reacts with a proton donor at the end where the charge is most stable. The attack of the proton donor in th© primary position is in accord with the work of -136- 11 and Yomip; (94). They found th^t -the sodium derivative of allylnennene, when treated with a motor donor, yave almost pure propenyltoensene• B. Experimental ?.nd Discussion of Cylcopentadiene 1. Preparation: Depolymorisa.tion of Dicyclo- pentadiene. Commercial dicyclonentadione (405 prams was depolyrncrised by belny heated at its bolliny point. The formed monomer wrs removed through an 1G inch Viyrerux column at a. rate of 30 cc per hour and collected in a receiver packed in Dry Ice (to prevent re-dimeriaatlon)* The crude cyclopentadien©(3l4 prams, 77. 5%, b.p. 41 - 42°C, n%° 1,4441) was used without further purification, except for filtration of a small amount of ice. v 2, Condensation with Kotones to prepare Dimethyl- cyclopentadier,yl carbinol Experiment Is Attempt to isolate alcoholate. Cyclopentadiene (198 yrams, 3,0 moles) was added rapidly to sodium amide (-3 moles) in 3 liters of liquid ammonia, which caused a vigorous reaction. Dry acetone (174 yrans, 3 moles) was added over a 10 minute period with little or no apparent reaction. The mixture was allowed to stir for three hours, and then the ammonia -137- w~ s allowed to evador*' to- over night. A l i -dvt brown crust formed, b u t before con plots, dryness was cer- fected, the notorial nolymerined. rapidly with genore - 1 1 on of c on s i de r o.bo l boat* The resultin'" blach, '•wmmy residue wns hydrolyzed sltt ice voter and 2_8 sulfuric acid, but th': material vac so viscous that only partial bo" arntion of the aqueous layer was nosr.ible* Steam distillation of the crude yielded, only a small m o u n t of a highly colored materi ul which nol’Ti' risod to a red, syrurrr oil in the receiver* fi'~cuc oi o n : ■ The sodium salt of the iesir ed fulvnnol was + * • •' • ror.tly obtain e " hut oolynorication of w - a conjugated hione aortlon of the mol ecule occurred as . t-enporature 'roaches room ternereture. Txnerinoni 2: Attempt to 1 sol- to ^Icohol The some procedure as used in er.ecriaent 1 eras followed 02:cent that the mixture eras quenched with ■mnonius chloride (162 yrerr, 3.0 moles). The nnronia was allo’.red to eveaoratc and product dissolved in methylene chloride. The mixture was go highly colored it was evident that dehydration had occurred forming the fulvene. The solvent was stripped off and the resi due ".ras washed sue cess full «v r vrith water,9 lrJ t sulf uri c acid, dilute sodium bicarbonate solution, and water, and then dried through ice-cooled sodium sulfato, -138- The crude (ll: yr c, n*^ 1.5465), a dvr1: cherry rod, w a topued under reduced pressure but rruvG no low boiliny material. It wan diluted in an equal volume oT n-pentane and was hydroyon atcd over 3 ,‘j its we 3 rht of Hr nop niolrol c talyet at IOC eel. At room -*■ .-f •"* i-"'.;.-’* 'V' ■"' *£, * p-pP “ ‘ *" iP> 7~j C* *'"'t “V ^ W - -■ >' ■**"■» «• "■ ^ ^ "* ’ -P**5- .— ■;:^ 'zourc tVe in a ox of1 r:fr:'ct? or; v :.c rtill 1*5103* 1 v a. '■. v'* a "■ 7 ", *» " •* f <■" f ' -pn' d ■p v P r-**yn ■ ■, i * * T ■ ^ * - -f* -yi 50 ^ 0 “ * b C C, and hydro--: nation continued for another 43 hours at 100 a.c.i. The m o u n t of hydro yon absorbed w\o approxin at oly 60.' of theory. the hydro yon at e was r:trin-od of solvent erf the crude (ifd?' 1.4611) distilled at 3-6 piates efficiency prior reduced pro sure to yield Of yr "ms di^t illir.y under 42°C/l6?Tffii * (c:., ir>0oC/760 nm) • This material (ndP 1.4393) vas unsaturated to bromine in carbon tetrachloride and was X rocharyed for further hydroycnation over U.O.?. niche 1 catalyst at 150°C at 1300 a.s.I. for 43 hours. The hydroporate was treated with aqueous potassium penmans— • rate for 24 hours at ice temperature to remove the residual uns aturatod material and then distilled at 15-20 plates efficiency'to five 16.1 proms (4.Q5 based on theory) of mood Isopropylcyclopentane. Tills material was combined with similar material for determination of physical oropertieE which are listed below: -139- I soorccvlo:pelop on tare This worh Li terature ( 32 ) (95) F.p. (;n.%)°C -111*83 -111.37 -111.7 P.p.°C/760 mm 116.51 126.42 126.4 -n d 4 0.7762 0.7765 0.7763 °0 n d 1.4260 1.4258 1.4260 HR found 37.01 ME calc 36.94 The excellent ^"T0 2:;!snt of physical ^ronertles and an infrared spectrum nearly identical with that of a hnoum sample proved definitely that ihl c me tori el was . i c c "•rorsel c v cloeent an e. 11 reussi on: The deeired fulvanol wus dehydrated. ujtider the conditions used. The * resulting fulvene was very difficult to hydrogenate; however this fact vrar anticipated since pervious vorhers h~-d encountered siril" r difficulty in hydro- -anution. A considerable amount of material was lost in Polymerization, not only in Isolation of the fulvene from the crude reaction products, but also in hydrogenation. The latter m a y explain the failure of dimethylfulvene to absorb the thooretical amount of hydrogen* Crane (95) postulated that the addition of hydrogen to dimethylfulvene may react in a maimer similar to the addition of sodium to form a dimeric compound of the type H CH(Na)-C(CH3)2 -C(CH3)2-CH(Na)R. -140- OHMS 14. IOO 14.200 14.050- 14.150 40C- - • - - I4.00C 14.300 14 . 250 - —4—4— 4 — 4 1— — ETN POINTMELTING CURVE OF isopropylcyclopentane TIME,MINUTES FIGURE VI FIGURE i — 4 — - 1 4 1 - i f — 4081 II1.83*0. ■- 14.018/1 Ixreriment 5: rJse of Solvents. The procodure described in run 2 was repeated except thet various solvents were added after approximately 9 0 ;t of* the ammonia Vw-d been evaporated* The mixture was warmed to 0°- 10°, but in each. cane a highly colored solution eras obtained before any at tempt was made to remove the residual ammonia. Apparently, the ammonia is nolar enough to affect a c “talytic dehydration w-f the desired fulvanol. The crude material war trashed with ice ’rater several timer:, dried, and then ■fraction-ted at 10 mm pressure. Any material bo 11 in^ below 30°C/5 mm was collected In a series of Dry Ice-cooled trars. Any distillable material above that temperature was ft highly unsaturated, and the temperature climbed steadily to 100°C/5 m:n with no discernible flats. Hon© of the desired alcohol was ever isolated. The * trap material, after washing with 1# sulfuric acid, dilute sodium bicarbonate solution, and drying, was hydrogenated as previously described. The yield of isopropylcyclopentane was approximately 3-10p based on theory. •142 3. Attempted Preparation of Dirnethylcyclopentenyl c arb1no1 f r om fulveilo 1 s . Ixnerlment It Reduction by Sodium and Ammonium Sulfate Cyclopentadienyl sodium (2*0 moles) was prepared in 3 liters of ammonia. After the addition of acetone (110 grams, 2.0 moles) , the mixture \>ms allowed to stir for two hours before ammonium sulfate (396 prams, t> equivalents) was added. Sodium (100 gram) was added piecemeal with a very slow evolution of hydro yen; but any additional sodium caused a, considerable liberation of hydror-en. The reaction was quenched with ammonium chloride and diluted with sufficient v/ater to cause the organic separation of material. After removal of the concentrated aqueous ammonia layer, the crude was washed twice in situ with cold water. The crude (74.2 grams, n%° 1.465S) was light yellow in color, but it had a heavy pungent odor. It was fractionated under reduced pressure of 10 mm, and the low boiling material collect ed in a series of Dry Ice-cooled traps. The distillable material (15.3 grams, 20.3>* b.p. 27-50°C/5 mm, 1*4633 - 1.4955) was not identified other than it did not have an alcoholic group and is presumably dimerI- nation products. The residue (12.3 grains, 16.4^) was polymeric in nature, but it did not resinify on further -143- heating. The trap material was washed and dried m & fractionated to yield 7 * 6 grama (b.p. 4-3*0 - 4-5-0°C, n|P 1*4-253 - 1*4315) which was primarily cyclopentene and 22 grams (b.p. 123,0 - 133,0°C, 1*4453 - 1*4655)* This higher boiling material was diluted in am equal volume of n-pentane and hydro genated over U.0.3?. nickel catalyst. It was necessary o _ to use extremely severe conditions, 175 C at 1300 p,s,i* before the slow absorption of hydrogen was completed. After treatment with aqueous potassium permanganate, the crude 15*1 grams (nil? 1*4271) was distilled to yield 9*3 grams of isopropylcyclopentane, (4r3/> yield). Discussion? Since none of the desired dimethylcyclopentenyl carbinol was never‘isolated, it can be assumed that the ammonium sulfate liberated the fulvanol which underwent dehydration and' subsequent reduction or that the allylic alcohol was reduced by the sodium -and ammonium sulfate. Since it has been shown that alkylation occurred primarily in the 2 position, it can. be assumed that cyclopentadlene condensed with acetone in a similar fashion; therefore, the alcohol is contained in an allylic system. If the cyclo- pentadionyl portion is reduced by sodium, the alcohol is still in an allylic system and can undergo further reduction to the monoolefin as previously described* -144- I i ® | > CH j —-i> q Q c - o * * — [}•-•-► L>-° c Hun 2; Reduction bv Sodium The same procedure was employed as in the previous run except tlvr.t ammonium sulfate was added after an attempt had been made to reduce the diene selectivity by sodium# Sodium (50 prams* 2.2 pram atom*) was added until the evolution of hydropen became brisk# Since this indie a. ted only 50 > reduction based on theory, ammonium sulfate (193 prams, 1.5 moles) was added batchwise# There was no apparent reaction, but shortly after the stirring was resumed, a vigorous reaction * occurred for a few minutes# Additional sodium (60 grams,.2#4 gram atoms) was added until a blue color persisted# The mixture was quenched with ammonium chloride and diluted with water; however, the organic material did not layer. It was necessary to effect separation of a red, oily material in a large volume of ice-water outside the reaction flask. Apparently, the addition of sodium had enhanced polymerisation because the' apparatus was coated with a light yellow ! polymeric oil# No attempt was made to further identi fy the reaction products# -145- Discussion: The reduction of the reaction products of cyclorentadlenylsodium end ketone is best effected by use of a proton donor. In all probability, the use of an alcohol as a proton donor would be more effective than ammonium sulfate, since a sodium compound Is readily de composed by a proton donor as indicated by the violence of the reaction vhen' efficient stirring: was resumed. This reaction did not give any conclusive evidence as to the nature of the reduction of the alcohol, but It Indicated that the dlene portion was reduced selectively, since nearly 50 > of the theoretical amount of sodium was consumed before -any liberation of hydropan. Then the ammonium sulfate decomposed the salt of the cyclopentenyl alcohol which underwent further reduction. However, reduc- * tion was not complete, even though the theoretical amount of sodium was used, which could indicate the consumption of sodium in poljTaer formation. The degree of polymerization was more severe in this experiment than in previous runs, but it was a. controlling factor In every experiment Involving this type of condensation. -146- 4. Attempted Preparation of* Methylethyleyclopentenyl Carblnol Experiment li Condensation with Ilethvl Ethyl Ketone at High Dilution, I-Iethyl ethyl ketone (36.0 rr^m, 0.5 moles) in 250 cc of n-pentane was added to an equimolecular quantity of cycloper-tadienylsodium in 2 liters of of ammonia. After s t i r r i n g for two hours, the mixture was reduced with sodium (30.0 grams, 1.3 gram atoms) and ammonium sulfate (2 equivalents)• Enough water was added to cause layering, and the organic marterial in n-pentsne was separated readily. The crude had a very slight color, and after washing, the entire charge was hydrogenated. Hydroyen absorption began at 80°C » at 900 p.s.i.; however, the conditions, vers eventually raised to 150°C at 1800 p.s.i. Fractionation yielded r.bout 5 grams of secondary butyl alcohol and 13.3 grams ofseconda,r3^ butylcj^clopentane as identified by comparison of properties and its infrared spectrum* sec. - Butvlcvclopentane This work Literature(95) \ o p.p. (m.p.) C glass glass -U • P. C°/760 mm ' 154.61 154.5 a s4° 0.793 6 0.7934 30 n& 1.4359 1.4357 -147- Discus cion: Tho higher dilution end the use of s. solvent '■•reatlv facilitated the recovery of oro&ucts and heloed control the decree of polymerisation. The reduction in sodium end liquid e.ir.onia was only about 65 complete; ’’.ovevsr, catalytic hydro yen at ion did not "ive any of the methyl ethyl cy cl orient enyl carblnol. Therefore, it can be assumed that reduction of the alcohol occurred, even though it is impossible to mako any definite conclusions. Polymerisation probably occurred, to some extent, during s the resctior in liquid ammonia as ".fell as during hydrogena- tion; but this is only an inference since the nature of the "olyaeric material vac not invest!mated. The isolation of sec.-butylcyclopontane (21*la) is indicative that condensation door occur, and that the -Icohol is dehydrated, in effect, at least, at some sta^e of the reduction in liquid ammonia. 5m Condensation of Cyclopentadlcno with Dibromiaes. Cy cl op or. t adi en e can be di alkylated by alkyl bro mides or sulfates (3) in a one-step or two-step process to produce predominately the 1 ,2-dialkylcyclopentadiene. There is a email amount of the 1,1- and 1,3-dialkyl isomers along* with some t r i alkyl at e d material. There- i fore, an attempt was made to dialkylate cyclopentadiene with dihalides with the possibility in mind of -148- pro''’0.rli'.a ricyclo cor.ipouri(',• I:i'~erlnG r,t 1.: Trimeth.yler.e fflbromlde Cy c l o pe n t a cl i en s (66 yrans, 1.0 moles) was added to sodium snide (2,0 noise) in tvo lite rs of liquid rnnnonla. Trimethyl©ne d?bromide (202 yrm s, 1.0 moles) r e a c t e d v l p o r o u s ly on addition. The mixture vac r.llO'.rod to s tir Tor on h o u r , then hydrolysed vith ammonium chloride and v"-ter* Tho orr/r.lc notorial had reiymericed to a bulhy, lig h t bro:msolid, v h i c h , o n drying, vas granular in consistency* Tho polymer was not s o lu h lD in a n y o r y m i c solvent and dissolved only vith de c c m e o s i t ion in concentr'-ted sulfuric acid. A sodium fusion tost did. net indicate any haloyen* Ihceorinort 2: Fort methylene Dibromide The same procedur used for trimethylene bromide was employed. Upon hydrolysis, a very spongy polymer use isolated, which differed from that ob tained with trimethylene dibronide in that it retained its spongy characteristics* It, too, vac insoluble in all organic solvents* -149- Tnnerlment 3 : Tetramethylene Dlbromide The sane procedure was employed, hut this tine a very viscous, light yellow, bromine free, polymeric liquid was obtained. It re sin! f led when an attempt was made to distill the crude under reduced pressure* Piscucciont The similar nature of the polymer resulting from 1,3-and 1,5-dihalidec would indicate that the same tvo© of oolvmerication had occurred and that the halogen s~ — — V atoms were sepe.ra.ted far enough, so as not to influence each other. ITo attempt was made to ascertain the molecular weight or any of the characteristics of tho polymers, but in all probability, the polymer formation resulted from inter- mole cula.r rather than intramolecular reaction* -150 SUIT1ARY I. (a) A procedure i;as developed for methylation or for allylation of 1,4-pentadiene through its sodium salt In liquid ammonia. Three hydrocarbons were Isolated and purified; 3 -methyl-1,4-pentadiere, 3 -vinyl-1,5-hexadione, and 4,4-divinyl-l,6 heptadiene (hitherto unkno’.m) • Their structures said the nature of the by-products formed by their reaiu^enrements during, the formation reaction were established by analysis, hydrorenation, and comparison of physical properties. The dimethylation product of 1,4-penta- dier.e, 3,3-dimethyl-1,4-pentadiene, was not isolated, but its presence was established by hydrorenation of mixtures containing it. The expected paraffin, 3 ,3-dimethylpentane, was isolated from the hydro genate. (b) 1 ,4-Heptadiene was prepared by selective cataly tic hydrogenation of l-hepten-4-yne. The above- mentioned methylation procedure was applied success fully to this 1,4-heptadiene, a derivative of 1,4- pentadiene in which one terminal hydrogen atom has been,replaced by an alkyl group. The raonomethylated product, 3 -methyl-1,4-heptadiene (new compound), was -151- Isolated and purified end vras identified by analysis, hydrorenation, and comparison of physical properties. The dlmethylated ^roduct vas formed in such an insig nificant amount that positive identification ’.r,r Imro nsiblc. . (a) One objective var ao study 1,4 enynor tb-t possessed tb•••'> same carbon skeleton as those of the 1,4 di Anothar objective of this uork vr-.s to prepare a hiably unsaturntod, non-con jugatr.d, aliphatic hydro carbon uithin tho gasoline bo i liny ran ye. Since the condensation of nllyl halides and sodium acetylide had been reported to produce an eight carbon and an eleven carbon fraction, thin reaction r-ras studied thoroughly * in lieu of nrencrino1 I .-penten-4-yn ical entity and studying its alkylation. The series of reactions which, occur uhen allyl chloride is condensed v;ith sodium acetjaLide in liquid ammonia was studied carefully. It was established that the first stop is formation of l-penten-4-yne, uhich undergoes further allylation at its methylene group to produce 4-vinyl-4-ethynyl-1,6-heptadiene. All attempts to isolate the primary, (unconjugated) five and eight earbon products vrere unsuccessful. The structure and the nature of the products that were -152 formed in the reaction rer''* deterninoi by analysis, hydro"onrtion, and oonp-'rlson of physical propertios• Th e A - v i r.vl -4 - o t! i vnvl -1,6 -he r> t ad i en e vs. s s u bin ittod I/ 4> -fc- t — for ermine tootiny and it proved to hsve unusual rroporties, (b) l-Hopten-4-yne (ne-„- compound) \ t ; \ s prepared by a mothod• Xt v/nr nothylnt "d by tbo procedure •» ■» r' y ^ -f'i'pv* » -r" *** ^ J- 1 Jl r ‘‘ "1 aprt e ■ L>«. *. . X v » . . i ■ : L j -i. ■ '- $ ‘ “ *' A *"" * — ..i.-. ; ,, 1 U ■— j' ^-{-y*""i ,«-*tod "T’o,oinJ' ( 7 —1 —hevtar —4—'mo, *'nd i" e by-vroducts formed by re a r r an yo a on t irors id e n tifie d by "roly'dE, hydro'••onation, and conpnlcon of >v-*p^’*r.,5 ^ ^ -j lnO^ OTT*'w i C‘S * (c) ."bo rosultr of methylatiny snd of a 11 ylatir~ aliphatic 1,4 unsrturr'tor throuyh their sodium salts in Ij.yuid sxr’cnia provided tho basis for tho following concluciors; (l) The nothylene yroup is activated by tvo adjacent carbon-to-carbon double bonds, or by a double bond and a. triple bond (both carbon-to- cr.rbon) , and its hydro yen atoms are more scidio than those of acetylene; the sodium salts of hydrocarbons vrith such methylene groups are not appreciably amvono- lyaed* (2) Methylation or allylntion occurs exclusively at tho methylone yroup. (3) There is little difference ir acidity or reactivity of methylene -I S3 - 1 - ^ T r ^ r- ■ 1 O ' ■ 0 , 7 0 -.ti Vt ^ ^ Jf .*h 1 ' ! 1^ ^ 9 CO TIi© re-'I •' c-r-'-’e'-t. of e ith e r v. term inal hydro ron •JOttI r~^~. •■ "? - rrg v»q —-or b*1" r'V"1 r*ppi »"o iji©PO ^ r :dcnc” to rer.rrc.r- u:i©:*tr. ohich fora CDr.jiv'-'tcd I r or. r: . ^ -"I \ f , -, . -- ■■ -• -t* ✓-> J-* ~| J_ r— t *? -v r «.-i ^ JJ ^ *, ^ :o:.:;' v c found To ' o o T ' c r.i © no -ol -:• f I r r: to th - e::- n * ^r-*> \*nl ,, ^ v^..-i ' * J 0 'w'-p ->. '„•.... . , - . - -• O . -i - ■. y .»■ ' • 1 » J - - . . - f- # «—s* , - - - r - >- . — .A V w ' - \ J -*• % . ■ ■ t * * - - > j - -» .. -i n t t’ o 1,4 eryvin '--rd/or J: V; ^ i.,4 T . . . i — U T ' f m>~*""V ' "* ’Vi^ r■*.- ;•* ■ o ,0 v* •"* ^ O 0 ^ O ^^ 3T*’~ ■hcLU J T ■> i*-', *~i n o J - - - *1 t— ■* >**,. 'A- ?* !-*» ^ * .■<*. «•• * t * 1 V > . . *_■ ^ b - -w -. ’• V . _ ’ « > » ' X » * ■ ' - k-V - ’ h-* >»»• ^ 9 ^o to :.cof. (n) C'-'iiy i:ncuccoctf'.H. otte:.:"Tr t .... To to i?e;po 11 t'oe -op-vioosl" 2.>c-'?.or‘t-'iT o o t of. ic 11 c •. '.1 rooction for the pro - — S . "I -V * ,- **• 4 - i -J--J 0 cloT::h t'’'-.- t tho orociouo ■..’or/or:: .--".p Vo..vo ;.hBinteroroted their r"-cultc* In t'oc 'orocont oorT it found ihrvfc tho- only ocet’rlenic I-r3.'ti. rT. i*ct"ort obt.,; ir.o-.T hp dis- colvln*"-- o c e t d m o i»i ©thereof, eclutlonr- of. ".r. od.h;rl — n:’.;-rcri'.n hror.ide h d^! - (br3:.ioma{Tn©riu;r.) reotrlide* ITor.e of tho dooirod etfr-ynyliac.niecinn bro::ii>ic tre.s over obtained,' txioufh various toc'mlcmen r d conditions vrere tried. An explanation :/as derived for the failure of the reactIon. -154- -, 4- -?- •-TVS £ "l ^ ' 'jlI l 11 o c o r ~ * > adi m e .■- dG'rrd/’obro: i ina t ina th e to tr ob r o:nide of l,4--io!:t::.diei‘o wit': sodium amide in lieuid auiuoniu. " ’ 1/ ^ o'1 r' ' *) O ~“T- ’! O O £) * * q **’, * f ***. *f*Q v^j ' ? ^ c*\ (o'* Li f^iur ncrt,"'1 *, *'} c> *■••>.->• **. to ’ic'" v_- an-ulo•~ou ol v td sodium acotvlido•- in reaction 'wit'; all'"I\S chloride in ^ i i ■* : ~T ^ ^ ' fr . ~ ^ 1 ?* t - ■' -m, "J^ "V*r r "T 0 . “* ' .-:> ' * -t ■** ^ ^ ’j * t O ■nJ'> -^ 7 i— "*",o r -'n '* *fn - f ' - no- - .-^ -j p - - -mi-'- ”1 --■ J -. —. -4o <— ^ o t /^1— ^"* ■'",!r- , lyl - ■- ■ ■■. wod, whi c': 1o ads to hi'ddly unrrr' t u r ,.,'t,ed hydrocarbons. iTie solubility of lithium acetyl.ids in 4- ,—•. J* ’’■'‘O 1 '**'! * *f^ rOO'l *tl# I""1 *' ’ i '"I * * '"'• r~ fo ;“■’ "' ;S\ '’V7C^ ^OT i:-)’"' ° *1^3 r- -'11 " n 1 J*„ ""'d.ui* O * "1 — J'^ny **,->. p olt' lnoi,1 0 ’jn.r';r, by too reaction of lithium ucetyli&e » and ally! bromide in tetrahydrofuron. V. Cyclopcntadieuo through its sodium salt, was success fully condensed with ho to nos in 1.1 -uid ammoni a medium* Hie structures of tin. oroducts ra the nature of the reaction were doteiT.iir.od bvh - cstrlvtlc V hydror©nation 1 . ■ _ of the fulvuiols first formed; alliylcyclooentanec were thus obtained. It was not rossl’ole to isolate tho fulvanols because of thoir 'ororonsit^ to dehudra11 on — * r and/or pol’Tierination. -155- C 'n e pbyr-icel property.e? of tne hyirocaroonE prepared i n t-iiio ressarcli \ror*o deie rained and recorded, the "'oriionc judr—d do be of beet, purity bein'*rood* V>r* j-. c fh V*0 '-*V»*d vr? ■» «■ J'* " d* Q*f^ £ \ "1. I*"’ O c2. ^ V3*iL "^O C ^ cT for moot of thee; hydrocarbons. -156- PLATE I „ V \ r V r > /A r— A 'A . 1 f A / i 1 D i w ----- L— —— \ L.. iB-- -- ns---- 4 WAVE LENGTH M-iJ MMHOMt L 4*4 - WVIWYL-1.6 - HEFTADICNC (prapara* from (.4 - ppntodiPM) V _ ' B L k v ~ r I /X /v> n.r1 v \ - f pr iV I —— 1 4 .4 -DtVINVt -1 3 ~HCPTAOICNE Ipwppwd 9-vinpl* L LCMOTM HOB*B’ 100 _ , ------lZnrto m 4*irHim-4*viwi- iji- MtrmtttNt gggg SElim v h o m U m . -157* PLATE II too W NI UEIMTN M 1.4 - HCfTAOtCNC ctuT i x m m sr. I i V 1 ■------— L I, J 3 -MTVMVL■ n -1 ,4 - HCFMttCNC i ******* c E T UMTTM OOM mmu OOj-----1----- mi ..... ATS V ■ 9 0 "S i f t 9 0 — 11 / m — t ---- ! — „ %— 1 — iB---- s ---- o---- 1 ■ , m m h L.• m m JB S. ... J 3- HmffL-l-MiPTlN-O-We i iwn S T L -158- PLATH III mmu* inaBm m ui 4-ETM YW L-4-VINYL- US— HCPTAOSNE HR CCU. UCNOTW 100 W\ • 9„ 0 n f ■ 9 0 L \ 1 w A/N — \r*C ---- jfj-- - 3 ---- „ ---- J Lr. ------Jt— 1 — " 1 9 ---- !»— 4-rrHTM VL-4-VIHYL“L«-M€PTAWCMC * O A O M S&. I 4.4-D«THVLHtPrANC n n u p M O «El lkmnm 8ft« -159- PLAT I: IV \ t V"Vf.. ii/Vii 1 / A. (V /N Y'A P > 1 «WVC LCNOTH M MtCMONi l-MEPTEN-4-YNE % * T t OCU. UtNKTH O.Otft* -a— — ws 5- Mmm.-i-HCFHN-4-vNc ffiSf I S P c E l i m t m S S A m L4-»«PtMXCMt m y u m 4 S B fuw rm Q m *160- B IB L I 0 C-RAPHY 1. Levy and Cope, J. Am Chem. Soc., 66, 1684 (1944). 2. Rovrlands, Dissertation, The Ohio St'ite Universit"', 0-952). 3. Oreenlee, Dissertation, The Ohio State University. (1942). 4. Campbell and Eby, J. Am. Cliem. Soc., 62., 216 (1941). 5. Boord, Henne. G-reenlee, Periletein, and Derfer, Ind. Bny. Chem., 41, 609 (1949). 6. Rowlands, private communication, publication pending. 7. Young, Prater, and Winstelr., J. Am. Chem. Soc. , 59, 2441 (1937). 8. G-reenles and Henne in Inormanic Syntheses. Vol. II, (W.C. Femelius, editor) • lie Craw Hill Booh Company (1946), socticnc 21 and 38* 9. Schr.iepp and Cellar, <7.Am, Chem. Soc., 67. 54 (1945). 10. Ton^berr and Fan she,Ind. Hny. Chem. Anal. 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Birch, J. Chem. Soc., (1944), 430. 93. Birch, J. Chem. Soc. (1945), 309. 94. Cammbell and Young, J. Am. Chem. Soc., 69. 633 (1947). *■ 95. Crane, Dissertation, The Ohio State University, (1940). 96. Chablny, Ann. Chim., 3, 192 (1917). 97* Lebeau and Picon, Comnt. rend., 159. 70 (1914). -165- ^ U T O ^ I O ^ * i r * . * m I* P.Vwrf oil Vferjier *vy\^ yi^-vr* *7° r ooi^n in ^r''"c d r• w ^ i X J C h l o , !’overIt or 14, 19.7.4. I received my ‘T, nn T school oluc tion In tie Csyvood school of Uiddlebury Town shin, V lino:-: County, Ohio. I yradu*-. tv.-d '.:1th honor:, from Frede- r i c l t o ’.m 171 rh School In Juno, 1942. I entered Ohio hss- 1 o ■*' • t l 77r.lvi- 1 1 ”' 7.':' Oct oh or . 1943 dor nv u n " © r^rciduc.t e t r ■ 1 r!■'■>r*. t « q ;«j y^co .oor. 1942 do Jn"1 * "t 0 4 5 , X r rvod In tho Unit 1 St"t : Ih.vy. Durlry : : y tenure of service, I w c ir 7 ••' 1 to bo - Coenuni e ■ tious :h “71 ■: ctroric Officer nt Ohio "losl-oym Uhiver-'ity, Column is. Ur Ivor el ty end 7Tor- vsrd University. I returned to Ohio Vecleym University in 7.946 ohd received tie dorroe B'.c’r l o r of Arte in 7,947. I entered The Ohio Ot'.tc University in 1947. lAri7,o vorh- iny tou r' the domree Doctor of Philosophy, I uo.c first of nil emyloyod by ti e chemistry de-~".rtmcrrt in 1943, t ’n n I he .Id ?. Roso-rrch Assist- ntehin on the American Petroleum Institute Rose .rch Pro 3 ct 4 5 t The Ohio St te Univer- ritjr until July, 1952, end then I received s. lonersl Mo tors Fellov.vl ' which continued until reyuirouents for’the derree wore fulfilled. I