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Matrix-Isolation FTIR Study of Azidoacetone and Azidoacetonitrile M
LOW TEMPERATURE PHYSICS VOLUME 29, NUMBER 9–10 SEPTEMBER–OCTOBER 2003 Matrix-isolation FTIR study of azidoacetone and azidoacetonitrile M. Frankowski,* B. S. Fox, A. M. Smith-Gicklhorn, M. K. Beyer, and V. E. Bondybey** Institute of Physical and Theoretical Chemistry, Technical University of Munich, Garching 85747, Germany M. Algarra and M. L. Costa CEFITEC, Department of Physics, Fac. Sciences and Technology, Universidade Nova de Lisboa, Caparica P-2829-516, Portugal P. Rodrigues and M. T. Barros CQFB, Department of Chemistry, Fac. Sciences and Technology, Universidade Nova de Lisboa, Caparica P-2829-516, Portugal M. N. D. S. Cordeiro REQUIMTE, Department of Chemistry, Fac. Sciences, Universidade do Porto, Porto 4169-007, Portugal Fiz. Nizk. Temp. 29, 1140–1146 ͑September–October 2003͒ Azidoacetonitrile (N3CH2CN) and azidoacetone (N3CH2COCH3) are studied by matrix-isolation FTIR spectroscopy in solid neon, argon, and nitrogen. The IR spectra calculated using the density-fuctional theoretical method are discussed in comparison with the experimental data. Significant broadening of the recorded azide bands indicate an awkward fit of these compounds into the solid environment. The strongest absorption is observed for both compounds in the regions of asymmetric and symmetric stretches of the N3 azide group. Strong band splittings in the N3 asymmetric stretch region can be most likely explained by very strong Fermi resonances with the CN stretch and combinations and overtones of the numerous lower- frequency vibrational modes. © 2003 American Institute of Physics. ͓DOI: 10.1063/1.1619361͔ INTRODUCTION EXPERIMENTAL Sample preparation Organic azides are useful reagents in many fields.1–3 Their strongly exothermic reactions make them useful as Azidoacetonitrile was synthesized from chloroacetoni- 4 propellants. -
Infrared Spectroscopy of Matrix-Isolated Polycyclic Aromatic Hydrocarbon Ions
J. Phys. Chem. A 2000, 104, 3655-3669 3655 Infrared Spectroscopy of Matrix-Isolated Polycyclic Aromatic Hydrocarbon Ions. 5. PAHs Incorporating a Cyclopentadienyl Ring† D. M. Hudgins,* C. W. Bauschlicher, Jr., and L. J. Allamandola NASA Ames Research Center, MS 245-6, Moffett Field, California 94035 J. C. Fetzer CheVron Research Company, Richmond, California 94802 ReceiVed: NoVember 5, 1999; In Final Form: February 9, 2000 The matrix-isolation technique has been employed to measure the mid-infrared spectra of the ions of several polycyclic aromatic hydrocarbons whose structures incorporate a cyclopentadienyl ring. These include the cations of fluoranthene (C16H10), benzo[a]fluoranthene, benzo[b]fluoranthene, benzo[j]fluoranthene, and benzo- [k]fluoranthene (all C20H12 isomers), as well as the anions of benzo[a]fluoranthene and benzo[j]fluoranthene. With the exception of fluoranthene, which presented significant theoretical difficulties, the experimental data are compared to theoretically calculated values obtained using density functional theory (DFT) at the B3LYP/ 4-31G level. In general, there is good overall agreement between the two data sets, with the positional agreement between the experimentally measured and theoretically predicted bands somewhat better than that associated with their intensities. The results are also consistent with previous experimental studies of polycyclic aromatic hydrocarbon ions. Specifically, in both the cationic and anionic species the strongest ion bands typically cluster in the 1450 to 1300 cm-1 range, reflecting an order-of-magnitude enhancement in the CC stretching and CH in-plane bending modes between 1600 and 1100 cm-1 in these species. The aromatic CH out-of- plane bending modes, on the other hand, are usually modestly suppressed (e 2x - 5x) in the cations relative to those of the neutral species, with the nonadjacent CH modes most strongly affected. -
Pinacol Rearrangement
Pinacol rearrangement The pinacol–pinacolone rearrangement is a method for converting a 1,2-diol to a carbonyl compound in organic chemistry. The 1,2-rearrangement takes place under acidic conditions. The name of the rearrangement reaction comes from the rearrangement of pinacol to pinacolone.[1] This reaction was first described by Wilhelm Rudolph Fittig in 1860 of the famed Fittig reaction involving coupling of 2 aryl halides in presence of sodium metal in dry ethereal solution.[2] Contents Mechanism Example of asymmetrical pinacol rearrangement Stereochemistry of the rearrangement History See also References Mechanism In the course of this organic reaction, protonation of one of the –OH groups occurs and a carbocation is formed. If the – OH groups are not alike (i.e. the pinacol is asymmetrical), then the one which creates a more stable carbocation participates in the reaction. Subsequently, an alkyl group from the adjacent carbon migrates to the carbocation center. The driving force for this rearrangement step is believed to be the relative stability of the resultant oxonium ion. Although the initial carbocation is already tertiary, the oxygen can stabilize the positive charge much more favorably due to the complete octet configuration at all centers. It can also be seen as the -OH's lone pairs pushing an alkyl group off as seen in the asymmetrical pinacol example. The migration of alkyl groups in this reaction occurs in accordance with their usual migratory aptitude, i.e.hydride > phenyl carbanion > tertiary carbanion (if formed by migration) > secondary carbanion (if formed by migration) > methyl carbanion. {Why carbanion? Because every migratory group leaves by taking electron pair with it.} The conclusion is that the group which stabilizes the carbocation more effectively is migrated. -
Bond Distances and Bond Orders in Binuclear Metal Complexes of the First Row Transition Metals Titanium Through Zinc
Metal-Metal (MM) Bond Distances and Bond Orders in Binuclear Metal Complexes of the First Row Transition Metals Titanium Through Zinc Richard H. Duncan Lyngdoh*,a, Henry F. Schaefer III*,b and R. Bruce King*,b a Department of Chemistry, North-Eastern Hill University, Shillong 793022, India B Centre for Computational Quantum Chemistry, University of Georgia, Athens GA 30602 ABSTRACT: This survey of metal-metal (MM) bond distances in binuclear complexes of the first row 3d-block elements reviews experimental and computational research on a wide range of such systems. The metals surveyed are titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and zinc, representing the only comprehensive presentation of such results to date. Factors impacting MM bond lengths that are discussed here include (a) n+ the formal MM bond order, (b) size of the metal ion present in the bimetallic core (M2) , (c) the metal oxidation state, (d) effects of ligand basicity, coordination mode and number, and (e) steric effects of bulky ligands. Correlations between experimental and computational findings are examined wherever possible, often yielding good agreement for MM bond lengths. The formal bond order provides a key basis for assessing experimental and computationally derived MM bond lengths. The effects of change in the metal upon MM bond length ranges in binuclear complexes suggest trends for single, double, triple, and quadruple MM bonds which are related to the available information on metal atomic radii. It emerges that while specific factors for a limited range of complexes are found to have their expected impact in many cases, the assessment of the net effect of these factors is challenging. -
Synthesis of Fused and Bridged Ring Systems James Nicolas Ong Sy Iowa State University
Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1988 Synthesis of fused and bridged ring systems James Nicolas Ong Sy Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Organic Chemistry Commons Recommended Citation Sy, James Nicolas Ong, "Synthesis of fused and bridged ring systems " (1988). Retrospective Theses and Dissertations. 9735. https://lib.dr.iastate.edu/rtd/9735 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. INFORMATION TO USERS The most advanced technology has been used to photo graph and reproduce this manuscript from the microfilm master. UMI films the original text directly from the copy submitted. Thus, some dissertation copies are in typewriter face, while others may be from a computer printer. In the unlikely event that the author did not send UMl a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyrighted material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are re produced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overlaps. Each oversize page is available as one exposure on a standard 35 mm slide or as a 17" x 23" black and white photographic print for an additional charge. -
1 Equilibria and Thermochemistry
k 1 1 Equilibria and Thermochemistry Answers to Problems Problem 1.1 A hydrocarbon, RH, can be isomerized in reversible reactions into two isomeric compounds P1 and P2 with the same heat of reaction. Both have C1 symmetry. P1 is a rigid molecule, and P2 is a flexible one adopting several conformations of similar stability. Which product will be preferred at equilibrium? Answer Products P1 and P2 equilibrate with RH in reversible reactions at temperature T.Thepreferredproductwillbe T ⇆ T T that for which the free energy of reaction ΔrG (reactants product P1 or P2) =ΔrH − TΔrS is the smallest. T ⇆ T ⇆ T T If ΔrH (RH P1) =ΔrH (RH P2), the product with the largest entropy (S (P1), S (P2)), will be favored at equilibrium at temperature T. Entropy expresses the degree of freedom available to an ensemble of molecules of a given compound. It depends upon the number of different microscopic states available to these molecules, and this depends on the size of the molecules themselves (P1 and P2 have the same molecular weight as they are isomers of the starting material RH), and the energy separation between the microscopic states available to them. k k The microscopic states that contribute most to the entropy are translational and rotational states for which the energy separation between quantum levels are the smallest. A rigid molecule is a molecule that does not equi- librate with several conformers of similar stabilities. It has only one energy minimum along all the coordinates that describe its geometrical deformations, including torsion about its -and-bonds and bond elongation. -
Organo-Transition Metal Chemistry Some Studies
ORGANO-TRANSITION METAL CHEMISTRY SOME STUDIES IN ORGANO-TRANSITION METAL CHEMISTRY By COLIN CRINDROD, B.Sc. A Thesis Submitted to the Faculty of Graduate Studies in Partial Fulfilment of the Requirements for the Degree Master of Science McMaster University October 1966 MASTER OF SCIENCE (1966) MCMASTER UNIVERSITY (Chemistry) Hamilton, Ontario TITLE: Some Studies in Organo-Transition Metal Chemistry AUTHOR: Colin Grindrod, B.Sc. (Manchester University) SUPERVISOR: Dr. P. M. Maitlis NUMBER OF PAGES: iv, 71 SCOPE AND CONTENTS: The work described is an extension of the ligand-transfer reactions of substituted cyclobutadienes and cyclopentadienyls previously carried out by Maitlis et al. Efforts were directed particularly to ligand transfer reactions of n-allyl-transition metal complexes. The reactions of organic halides with metal carbonyls were also studied in attempts to isolate new organometallic derivatives. (ii) ACKNOWLEDGEMENTS The author wishes to express his sincere gratitude for the stimulating advice and constant encouragement provided by Dr. P. M. Maitlis, under whose guidance this work was carried out. Thanks are also extended to Imperial Oil Co. Ltd. for providing the financial support which made this study possible. (iii) CONTENTS Page INTRODUCTION Historical................................... 1 Cyclobutadiene-transition metal oompeeees... 7 Ligand-transfer reactions................... 10 Allyl-transition metal complexes............ 13 Reactions of metal carbonyls with organic halides.... ..................... 25 DISCUSSION -
A MATRIX ISOLATION SPECTROSCOPIC INVESTIGATION of the REACTION PRODUCTS of TRANSITION METAL CENTRES with ETHENE and WATER By
A MATRIX ISOLATION SPECTROSCOPIC INVESTIGATION OF THE REACTION PRODUCTS OF TRANSITION METAL CENTRES WITH ETHENE AND WATER by MATTHEW G. K. THOMPSON A thesis submitted to the Department of Chemistry in conformity with the requirements for the degree of Doctor of Philosophy Queen’s University Kingston, Ontario, Canada November 2007 Copyright © Matthew Gary Karl Thompson, 2007 Abstract The reaction products of thermally generated atomic V with ethene and ethene isotopomers have been investigated by matrix isolation ultraviolet visible and Fourier transform infrared (FTIR) spectroscopy. When V is deposited into matrices of pure Ar, evidence for V and V2 are present in the UV-visible absorption spectra. Addition of trace amounts of ethene results in the elimination of absorptions due to V2 on deposition, likely due to the formation of … V (C2H4) van der Waals complexes on matrix condensation. Irradiation of matrices containing V and trace C2H4 in Ar, with light corresponding to atomic V electronic excitations, eliminates all UV-visible absorptions due to atomic V in the matrix. Infrared analysis of matrices containing V and C2H4 give evidence for a new product on deposition, consistent with a kinetically formed H-V-C2H3 isomer. Following further irradiation of the matrix, several new products of C-H bond insertion by the metal atom, including additional H-V-C2H3 conformational 2 isomers, and H2V(η -C2H2) products are observed in the infrared spectrum. Additionally, the formation of ethane is evident as a major product immediately following deposition of V + C2H4 + H2O in Ar. The formation of this product is consistent with alkene insertion into the V-H bond of an H-V-OH intermediate, followed by a photo-induced elimination to give C2H6. -
Pinacol Rearrangement
Pinacol rearrangement The pinacol–pinacolone rearrangement is a method for converting a 1,2-diol to a carbonyl compound in organic chemistry. The 1,2-rearrangement takes place under acidic conditions. The name of the rearrangement reaction comes from the rearrangement of pinacol to pinacolone.[1] This reaction was first described by Wilhelm Rudolph Fittig in 1860 of the famed Fittig reaction involving coupling of 2 aryl halides in presence of sodium metal in dry ethereal solution.[2] Contents Mechanism Stereochemistry of the rearrangement History See also References Mechanism In the course of this organic reaction, protonation of one of the –OH groups occurs and a carbocation is formed. If both the –OH groups are not alike, then the one which yields a more stable carbocation participates in the reaction. Subsequently, an alkyl group from the adjacent carbon migrates to the carbocation center. The driving force for this rearrangement step is believed to be the relative stability of the resultant oxonium ion, which has complete octet configuration at all centers (as opposed to the preceding carbocation). The migration of alkyl groups in this reaction occurs in accordance with their usual migratory aptitude, i.e.hydride > phenyl carbanion > tertiary carbanion (if formed by migration) > secondary carbanion (if formed by migration) > methyl carbanion . {Why Carbanion? Because every migratory group leaves by taking electron pair with it.} The conclusion is that the group which stabilizes the carbocation more effectively is migrated. Stereochemistry of the rearrangement In cyclic systems, the reaction presents more features of interest. In these reactions, the stereochemistry of the diol plays a crucial role in deciding the major product. -
El Reactivo De Tollens: De La Identificación De Aldehídos a Su Uso En Nanotecnología
173ENSEÑANZA EN EL AULA EL REACTIVO DE TOLLENS: DE LA IDENTIFICACIÓN DE ALDEHÍDOS A SU USO EN NANOTECNOLOGÍA. ASPECTOS HISTÓRICOS Y APLICACIONES DIDÁCTICAS El reactivo de Tollens: de la identifi cación de aldehídos a su uso en nanotecnología. Aspectos históricos y aplicaciones didácticas Gabriel Pinto, Manuela Martín, José María Hernández, María Teresa Martín Resumen: Se recoge una reseña biográfi ca del químico alemán Bernhard Tollens (1841-1918), donde se resalta su labor en el estudio de la estructura y el análisis de compuestos orgánicos. Se destaca también su ejemplar implicación en tareas docentes sobre química agrícola con estudiantes de muy diversos países. Se describen las características del reactivo que inventó, que lleva su nombre, y que al reaccionar con aldehídos proporciona una de las experiencias más vistosas de las prácticas de Química Orgánica de alumnos universitarios: la formación de un “espejo de plata”. Finalmente, se exponen ideas sobre la posible utilización (en investigación y en actividades educativas) del reactivo de Tollens para la obtención y caracterización de nanopartículas de plata, con importancia en distintas aplicaciones. Palabras clave: Biografía de Bernhard Tollens, Identifi cación de aldehídos, Nanopartículas de plata, Nanotecnología, Reactivo de Tollens. Abstract: A short biography of the German chemist Bernhard Tollens (1841-1918) is included, which highlights his works in the study of the structure and analysis of organic compounds. His exemplary involvement in teaching activities on agricultural chemistry with students from many different countries is also emphasized. The characteristics of the reagent invented by him, known by his name, are described. The Tollens’ reagent reacts with aldehydes, providing one of the most attractive experience lab works of undergraduate students of Organic Che- mistry: the formation of a “silver mirror”. -
Matrix Isolation and Computational Study of Isodifluorodibromomethane (F2 Cbr-Br): a Route to Br2 Formation in Cf2 Br2 Photolysis
Bowling Green State University ScholarWorks@BGSU Chemistry Faculty Publications Chemistry 2010 Matrix Isolation and Computational Study of Isodifluorodibromomethane (F2 Cbr-Br): A Route to Br2 Formation in Cf2 Br2 Photolysis Alexander N. Tarnovsky Bowling Green State University, [email protected] Lisa George Aimable Kalume Patrick Z. El-Khoury Scott A. Reid Follow this and additional works at: https://scholarworks.bgsu.edu/chem_pub Part of the Chemistry Commons Repository Citation Tarnovsky, Alexander N.; George, Lisa; Kalume, Aimable; El-Khoury, Patrick Z.; and Reid, Scott A., "Matrix Isolation and Computational Study of Isodifluorodibromomethane (F2 Cbr-Br): A Route to Br2 Formation in Cf2 Br2 Photolysis" (2010). Chemistry Faculty Publications. 26. https://scholarworks.bgsu.edu/chem_pub/26 This Article is brought to you for free and open access by the Chemistry at ScholarWorks@BGSU. It has been accepted for inclusion in Chemistry Faculty Publications by an authorized administrator of ScholarWorks@BGSU. THE JOURNAL OF CHEMICAL PHYSICS 132, 084503 ͑2010͒ Matrix isolation and computational study of isodifluorodibromomethane „F2CBr–Br…: A route to Br2 formation in CF2Br2 photolysis Lisa George,1 Aimable Kalume,1 Patrick Z. El-Khoury,2 Alexander Tarnovsky,2 and ͒ Scott A. Reid1,a 1Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881, USA 2Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, USA ͑Received 29 November 2009; accepted 26 January 2010; published online 22 February 2010͒ ͑ ͒ The photolysis products of dibromodifluoromethane CF2Br2 were characterized by matrix isolation infrared and UV/Visible spectroscopy, supported by ab initio calculations. Photolysis at ͑ϳ ͒ ϳ wavelengths of 240 and 266 nm of CF2Br2 :Ar samples 1:5000 held at 5 K yielded ͑ ͒ iso-CF2Br2 F2CBrBr , a weakly bound isomer of CF2Br2, which is characterized here for the first time. -
Arghya Chakraborty
Electronic Characterization of Mass-Selected Acyclic, Polycyclic and Oxygenated Hydrocarbons in Neon Matrices INAUGURALDISSERTATION zur Erlangung der Würde eines Doktors der Philosophie vorgelegt der Philosophisch-Naturwissenschaftlichen Fakultät der Universität Basel von Arghya Chakraborty aus Westbengal, Indien Basel, 2016 Originaldokument gespeichert auf dem Dokumentenserver der Universität Basel edoc.unibas.ch 1 Genehmigt von der Philosophisch-Naturwissenschaftlichen Fakultät auf antrag von Dissertationsleiter: Prof. Dr. John. P. Maier Korreferent: Prof. Dr. Stefan Willitsch Basel, 23 Februar 2016 Prof. Dr. J. Schibler Dekan 2 Electronic Characterization of Mass-Selected Acyclic, Polycyclic and Oxygenated Hydrocarbons in Neon Matrices PhD THESIS Of ARGHYA CHAKRABORTY Basel 2016 3 4 Acknowledgements A researcher needs a healthy working atmosphere to be productive. The work and personal life in Basel would not have been so pleasant without the guidance and support of several individuals. First of all, I would like to thank Prof. John Paul Maier for his constant endorsement, supervision and providing world class experimental facilities in laboratory. Beside science, I have learned lots of technical skills from him and hopefully will apply them in my entire career. I am very much thankful to Prof. Stefan Willitsch for being the co-referee of my thesis. Prof. Markus Meuwly is thanked for accepting to be the chair in my PhD defense. Heartiest thank of mine goes to Dr. Jan Fulara for teaching me the essentials of the matrix isolation set-up, sharing his deep knowledge on spectroscopy and helping with his computational skill. Special thanks are also addressed to Dr. Corey Rice for his advices, explanations and experimental ideas. I am highly privileged to him for being the proof reader of my thesis.