Cyclooctatetraenes Through Valence Isomerization of Cubanes
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Transport of Dangerous Goods
ST/SG/AC.10/1/Rev.16 (Vol.I) Recommendations on the TRANSPORT OF DANGEROUS GOODS Model Regulations Volume I Sixteenth revised edition UNITED NATIONS New York and Geneva, 2009 NOTE The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the United Nations concerning the legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. ST/SG/AC.10/1/Rev.16 (Vol.I) Copyright © United Nations, 2009 All rights reserved. No part of this publication may, for sales purposes, be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, electrostatic, magnetic tape, mechanical, photocopying or otherwise, without prior permission in writing from the United Nations. UNITED NATIONS Sales No. E.09.VIII.2 ISBN 978-92-1-139136-7 (complete set of two volumes) ISSN 1014-5753 Volumes I and II not to be sold separately FOREWORD The Recommendations on the Transport of Dangerous Goods are addressed to governments and to the international organizations concerned with safety in the transport of dangerous goods. The first version, prepared by the United Nations Economic and Social Council's Committee of Experts on the Transport of Dangerous Goods, was published in 1956 (ST/ECA/43-E/CN.2/170). In response to developments in technology and the changing needs of users, they have been regularly amended and updated at succeeding sessions of the Committee of Experts pursuant to Resolution 645 G (XXIII) of 26 April 1957 of the Economic and Social Council and subsequent resolutions. -
Aromaticity Sem- Ii
AROMATICITY SEM- II In 1931, German chemist and physicist Sir Erich Hückel proposed a theory to help determine if a planar ring molecule would have aromatic properties .This is a very popular and useful rule to identify aromaticity in monocyclic conjugated compound. According to which a planar monocyclic conjugated system having ( 4n +2) delocalised (where, n = 0, 1, 2, .....) electrons are known as aromatic compound . For example: Benzene, Naphthalene, Furan, Pyrrole etc. Criteria for Aromaticity 1) The molecule is cyclic (a ring of atoms) 2) The molecule is planar (all atoms in the molecule lie in the same plane) 3) The molecule is fully conjugated (p orbitals at every atom in the ring) 4) The molecule has 4n+2 π electrons (n=0 or any positive integer Why 4n+2π Electrons? According to Hückel's Molecular Orbital Theory, a compound is particularly stable if all of its bonding molecular orbitals are filled with paired electrons. - This is true of aromatic compounds, meaning they are quite stable. - With aromatic compounds, 2 electrons fill the lowest energy molecular orbital, and 4 electrons fill each subsequent energy level (the number of subsequent energy levels is denoted by n), leaving all bonding orbitals filled and no anti-bonding orbitals occupied. This gives a total of 4n+2π electrons. - As for example: Benzene has 6π electrons. Its first 2π electrons fill the lowest energy orbital, and it has 4π electrons remaining. These 4 fill in the orbitals of the succeeding energy level. The criteria for Antiaromaticity are as follows: 1) The molecule must be cyclic and completely conjugated 2) The molecule must be planar. -
Recent Studies on the Aromaticity and Antiaromaticity of Planar Cyclooctatetraene
Symmetry 2010 , 2, 76-97; doi:10.3390/sym2010076 OPEN ACCESS symmetry ISSN 2073-8994 www.mdpi.com/journal/symmetry Review Recent Studies on the Aromaticity and Antiaromaticity of Planar Cyclooctatetraene Tohru Nishinaga *, Takeshi Ohmae and Masahiko Iyoda Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan; E-Mails: [email protected] (T.O.); [email protected] (M.I.) * Author to whom correspondence should be addressed; E-Mail: [email protected]. Received: 29 December 2009; in revised form: 23 January 2010 / Accepted: 4 February 2010 / Published: 5 February 2010 Abstract: Cyclooctatetraene (COT), the first 4n π-electron system to be studied, adopts an inherently nonplanar tub-shaped geometry of D2d symmetry with alternating single and double bonds, and hence behaves as a nonaromatic polyene rather than an antiaromatic compound. Recently, however, considerable 8 π-antiaromatic paratropicity has been shown to be generated in planar COT rings even with the bond alternated D4h structure. In this review, we highlight recent theoretical and experimental studies on the antiaromaticity of hypothetical and actual planar COT. In addition, theoretically predicted triplet aromaticity and stacked aromaticity of planar COT are also briefly described. Keywords: antiaromaticity; cyclooctatetraene; NMR chemical shifts; quantum chemical calculations; ring current 1. Introduction Cyclooctatetraene (COT) was first prepared by Willstätter in 1911 [1,2]. At that time, the special stability of benzene was elusive and it was of interest to learn the reactivity of COT as the next higher vinylogue of benzene. However, unlike benzene, COT was found to be highly reactive to electrophiles just like other alkenes. -
Xarox University Microfilms
INFORMATION TO USERS Thil material was produced from a microfilm copy of the original documant. While the moat advanced technological meant to photograph and reproduce this documant have been used, the quality is heavily dependant upon the quality of the original submitted. The following explanation o f techniques is provided to help you understand markings or patterns which m ay appear on this reproduction. 1. The sign or "target" for pages apparently lacking from the document photographed is "Misting Page(s)". If it was possible to obtain the misting page(s) or section, th a y era spliced into the film along with adjacent pages. This may have necessitated cutting thru an image and duplicating adjacent pagae to insure you complete continuity. 2. Whan an image on th e film is obliterated with a large round black mark, it is an indication that the photographer suspected that the copy may have moved during exposure and thus causa a blurred image. You will find a good image of the pnga in the adjacent frame. 3. Whan a map, drawing or chart, etc., was part of the material being photographed the photographer followed a definite method in "sectioning" the material. It ie customary to begin photoing at the upper left hand comer of a large sheet and to continue photoing from left to right in equal sections with a small overlap. If necessary, sectioning is continued again — beginning below the first row end continuing on until complete. 4. The majority of users indicate that the textual content is of greatest value, however, a somewhat higher quality reproduction could be made from "photographs" if essential to the understanding of the dissertation. -
37Th Rocky Mountain Conference on Analytical Chemistry
Rocky Mountain Conference on Magnetic Resonance Volume 37 37th Rocky Mountain Conference on Article 1 Analytical Chemistry July 1995 37th Rocky Mountain Conference on Analytical Chemistry Follow this and additional works at: https://digitalcommons.du.edu/rockychem Part of the Chemistry Commons, Materials Science and Engineering Commons, and the Physics Commons Recommended Citation (1995) "37th Rocky Mountain Conference on Analytical Chemistry," Rocky Mountain Conference on Magnetic Resonance: Vol. 37 , Article 1. Available at: https://digitalcommons.du.edu/rockychem/vol37/iss1/1 This work is licensed under a Creative Commons Attribution 4.0 License. This Article is brought to you for free and open access by Digital Commons @ DU. It has been accepted for inclusion in Rocky Mountain Conference on Magnetic Resonance by an authorized editor of Digital Commons @ DU. For more information, please contact [email protected],dig- [email protected]. et al.: 37th RMCAC Final Program and Abstracts 37TH ROCKY MOUNTAIN CONFERENCE ON ANALYTICAL CHEMISTRY FINAL PROGRAM AND ABSTRACTS JULY 23-27, 1995 HYATT REGENCY DENVER 1750 WELTON STREET DENVER, COLORADO SPONSORED BY: ROCKY MOUNTAIN SECTION SOCIETY FOR APPLIED SPECTROSCOPY & COLORADO SECTION AMERICAN CHEMICAL SOCIETY Published by Digital Commons @ DU, 1995 1 Rocky Mountain Conference on Magnetic Resonance, Vol. 37 [1995], Art. 1 TABLE OF CONTENTS Conference Organizers 2 Symposia Organizers 3 Registration and Event Information 5 Exhibitor List 8 Hotel and Visitor Information 9 Employment Clearing House and Professional Memberships 9 Short Courses 10 Vendor Workshops 12 Symposia Schedule: Atomic Spectroscopy 17 Chromatography 18 Compost (Biogeochemistry of) 19 Electrochemistry 20 Environmental Chemistry 22 EPR 25 FTIR/NIR/RAMAN Spectroscopy 37 General Posters 37 ICP-MS 39 Laboratory Safety 41 Luminescence 42 Mass Spectrometry 44 NMR 47 Pharmaceutical Analysis 59 Quality Assurance 60 Downtown Denver Street Map Inside back cover Abstracts start after page 61. -
Chemical Redox Agents for Organometallic Chemistry
Chem. Rev. 1996, 96, 877−910 877 Chemical Redox Agents for Organometallic Chemistry Neil G. Connelly*,† and William E. Geiger*,‡ School of Chemistry, University of Bristol, U.K., and Department of Chemistry, University of Vermont, Burlington, Vermont 05405-0125 Received October 3, 1995 (Revised Manuscript Received January 9, 1996) Contents I. Introduction 877 A. Scope of the Review 877 B. Benefits of Redox Agents: Comparison with 878 Electrochemical Methods 1. Advantages of Chemical Redox Agents 878 2. Disadvantages of Chemical Redox Agents 879 C. Potentials in Nonaqueous Solvents 879 D. Reversible vs Irreversible ET Reagents 879 E. Categorization of Reagent Strength 881 II. Oxidants 881 A. Inorganic 881 1. Metal and Metal Complex Oxidants 881 2. Main Group Oxidants 887 B. Organic 891 The authors (Bill Geiger, left; Neil Connelly, right) have been at the forefront of organometallic electrochemistry for more than 20 years and have had 1. Radical Cations 891 a long-standing and fruitful collaboration. 2. Carbocations 893 3. Cyanocarbons and Related Electron-Rich 894 Neil Connelly took his B.Sc. (1966) and Ph.D. (1969, under the direction Compounds of Jon McCleverty) degrees at the University of Sheffield, U.K. Post- 4. Quinones 895 doctoral work at the Universities of Wisconsin (with Lawrence F. Dahl) 5. Other Organic Oxidants 896 and Cambridge (with Brian Johnson and Jack Lewis) was followed by an appointment at the University of Bristol (Lectureship, 1971; D.Sc. degree, III. Reductants 896 1973; Readership 1975). His research interests are centered on synthetic A. Inorganic 896 and structural studies of redox-active organometallic and coordination 1. -
7 Benzene and Aromatics
Benzene and Aromatic Compounds Chapter 15 Organic Chemistry, 8th Edition John McMurry 1 Background • Benzene (C6H6) is the simplest aromatic hydrocarbon (or arene). • Four degrees of unsaturation. • It is planar. • All C—C bond lengths are equal. • Whereas unsaturated hydrocarbons such as alkenes, alkynes and dienes readily undergo addition reactions, benzene does not. • Benzene reacts with bromine only in the presence of FeBr3 (a Lewis acid), and the reaction is a substitution, not an addition. 2 The Structure of Benzene: MO 3 The Structure of Benzene: Resonance The true structure of benzene is a resonance hybrid of the two Lewis structures. 4 Aromaticity – Resonance Energy 5 Stability of Benzene - Aromaticity Benzene does not undergo addition reactions typical of other highly unsaturated compounds, including conjugated dienes. 6 The Criteria for Aromaticity Four structural criteria must be satisfied for a compound to be aromatic. [1] A molecule must be cyclic. 7 The Criteria for Aromaticity [2] A molecule must be completely conjugated (all atoms sp2). 8 The Criteria for Aromaticity [3] A molecule must be planar. 9 The Criteria for Aromaticity—Hückel’s Rule [4] A molecule must satisfy Hückel’s rule. 10 The Criteria for Aromaticity—Hückel’s Rule 1. Aromatic—A cyclic, planar, completely conjugated compound with 4n + 2 π electrons. 3. Antiaromatic—A cyclic, planar, completely conjugated compound with 4n π electrons. 5. Not aromatic (nonaromatic)—A compound that lacks one (or more) of the following requirements for aromaticity: being cyclic, -
Synthesis and Reactions of 4,5-Homotropone and 4,5-Dimethylenetropone Richard Anthony Fugiel Iowa State University
Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1974 Synthesis and reactions of 4,5-homotropone and 4,5-dimethylenetropone Richard Anthony Fugiel Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Organic Chemistry Commons Recommended Citation Fugiel, Richard Anthony, "Synthesis and reactions of 4,5-homotropone and 4,5-dimethylenetropone " (1974). Retrospective Theses and Dissertations. 5986. https://lib.dr.iastate.edu/rtd/5986 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]. INFORIVIATIOIM TO USERS This material was produced from a microfilm copy of the original document. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the original submitted. The following explanation of techniques is provided to help you understand markings or patterns which may appear on this reproduction. 1.The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)". If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting thru an image and duplicating adjacent pages to insure you complete continuity. 2. When an image on the film is obliterated with a large round black mark, it is an indication that the photographer suspected that the copy may have moved during exposure and thus cause a blurred image. -
Information to Users
INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand corner and continuing from left to right in equal sections with small overlaps. Each original is also photographed in one exposure and is included in reduced form at the back of the book. Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. University Microfilms international A Bell & Howell Information Company 300 North ZeebRoad Ann Arbor Ml 48106-1346 USA 313/761-4700 800 521-0600 Order Number 9427071 The chemistry of polycyclic and spirocyclic compounds Branan, Bruce Monroe, Ph.D. The Ohio State University, 1994 UMI 300 N.ZeebRd. Ann Arbor, MI 48106 THE CHEMISTRY OF POLYCYCLIC AND SPIROCYCLIC COMPOUNDS DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University by Bruce Monroe Branan ***** The Ohio State University 1994 Dissertation Committee: Approved by Professor Leo A. -
UNITED STATES PATENT OFFICE 2,613,23I PREPARATION of Cyclooctatetraene Alfred J
Patented Oct. 7, 1952 2,613,231 UNITED STATES PATENT OFFICE 2,613,23i PREPARATION of CYCLooCTATETRAENE Alfred J. Canale, Moorestown, and John F. Kin caid, Mount Holly, N.J., assignors to Rohm & in Haas Company, Philadelphia, Pa., a corporation. of Delaware. No Drawing. Application March 9, 1950, Serial No. 148,734 4 Claims. (CI. 260-666) 1 . 2 This invention deals with the preparation of monocyanide is taken in an amount which is one cyclooctatetraene by tetramerizing acetylene in fifth of the weight of nickelous cyanide, the rate the presence of nickel monocyanide, NiCN, as is 60 grams per liter-hour. catalyst. Solvents which are useful for wetting and sus It was discovered by Reppe and coworkers that pending the nickel monocyanide include not only cycloctatetraene is formed when acetylene is dioxane and tetrahydrofurane which have been heated in the presence of nickelous cyanide, mentioned but also water-miscible diethers of Ni(CN)2, suspended in tetrahydrofurane in the glycols, such as the dimethyl ethers of ethylene presence of calcium carbide or ethylene oxide. glycol, diethylene glycol, triethylene glycol, tetra Great stress was placed upon the necessity of an 10 ethylene glycol, propylene glycol, or dipropylene hydrous conditions. The reaction as carried out glycol, diethyl ethers of these glycols, mixed meth was slow, not particularly efficient in time or ma yl and ethyl ethers thereof, and mixtures of terials, and not truly reproducible. For the prac the various diethers. Another type of ether com tical preparation of cyclooctatetraene it is al prises acetals, such as dibutyl acetal, dipropyl most essential that shortcomings and difficulties 15 acetal, diethyl-formal, dibutyl formal, etc. -
73C0b6de7efdff4076a7d398d06
Molecules 2014, 19, 6987-7007; doi:10.3390/molecules19066987 OPEN ACCESS molecules ISSN 1420-3049 www.mdpi.com/journal/molecules Review Experimental and Theoretical Perspectives of the Noyori-Ikariya Asymmetric Transfer Hydrogenation of Imines Jiří Václavík 1, Petr Šot 1, Jan Pecháček 1, Beáta Vilhanová 1, Ondřej Matuška 1, Marek Kuzma 2 and Petr Kačer 1,* 1 Department of Organic Technology, Institute of Chemical Technology, Technická 5, CZ-166 28 Prague, Czech Republic 2 Laboratory of Molecular Structure Characterization, Institute of Microbiology, v.v.i., Academy of Sciences of the Czech Republic, Vídeňská 1083, CZ-142 20 Prague, Czech Republic * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +420-220-444-158; Fax: +420-220-444-340. Received: 28 February 2014; in revised form: 13 May 2014 / Accepted: 21 May 2014 / Published: 28 May 2014 Abstract: The asymmetric transfer hydrogenation (ATH) of imines catalyzed by the Noyori-Ikariya [RuCl(η6-arene)(N-arylsulfonyl-DPEN)] (DPEN = 1,2-diphenylethylene- 1,2-diamine) half-sandwich complexes is a research topic that is still being intensively developed. This article focuses on selected aspects of this catalytic system. First, a great deal of attention is devoted to the N-arylsulfonyl moiety of the catalysts in terms of its interaction with protonated imines (substrates) and amines (components of the hydrogen-donor mixture). The second part is oriented toward the role of the η6-coordinated arene. The final part concerns the imine substrate structural modifications and their importance in connection with ATH. Throughout the text, the summary of known findings is complemented with newly-presented ones, which have been approached both experimentally and computationally. -
Aromaticity of Polycyclic Conjugated Hydrocarbons
Chem. Rev. 2003, 103, 3449−3605 3449 Aromaticity of Polycyclic Conjugated Hydrocarbons Milan Randic´* National Institute of Chemistry, Ljubljana, Slovenia Received December 13, 2001 Contents I. Prologue 3451 II. Introduction 3455 III. Dilemmas 3456 A. Qualitative versus Quantitative Approaches 3456 B. Observables versus Non-observables 3458 C. Structural Criteria versus Properties as Criteria 3459 D. Valence Bond Theory versus Molecular Orbital 3460 Theory E. On Interlocking of the MO and the VB 3461 Methods F. Chemical Graph Theory versus Quantum 3462 Chemistry G. Clar 6n Rule versus Hu¨ckel 4n + 2 Rule 3464 H. Hydrocarbons versus Heteroatomic Systems 3465 Milan Randic´ is a native of Croatia, born in 1930, and is a citizen of the IV. Hidden Treasures of Kekule´ Valence Structures 3466 United States and Croatia. He studied theoretical physics at the University A. Conjugated Circuits 3467 of Zagreb (1954) under Professor Ivan Supek (a student of Werner B. Innate Degree of Freedom 3470 Heisenberg). Supek introduced him to the book by Linus Pauling, The Nature of the Chemical Bond, with a request to get involved in quantum C. Clar Structures 3472 chemistry. He got his Ph.D. degree in Cambridge in 1958, studying high- V. Graph Theoretical Approach to Chemical Structure 3473 resolution infrared molecular spectra with Dr. Norman Sheppard. At the A. Metric 3473 Rudjer Bosˇkovic´ Institute in Zagreb, Croatia, in 1960, he founded the B. Chemical Graphs 3473 theoretical chemistry group. Since 1971, he has visited several U.S. universities. From 1980 to 2000, he was in the Department of Mathematics C. Isospectral Graphs 3473 and Computer Science at Drake University, Des Moines, Iowa.