ORGANIC CHEMISTRY I – PRACTICE EXERCISE Elimination Reactions and Alkene Synthesis 1) One of the Products That Results When 1
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Elimination Reactions E1, E2, E1cb and Ei
Elimination Reactions Dr. H. Ghosh Surendranath College, Kol-9 ________________________________________________ E1, E2, E1cB and Ei (pyrolytic syn eliminations); formation of alkenes and alkynes; mechanisms (with evidence), reactivity, regioselectivity (Saytzeff/Hofmann) and stereoselectivity; comparison between substitution and elimination. Substitution Reactions Elimination Reactions Elimination happens when the nucleophile attacks hydrogen instead of carbon Strong Base favor Elimination Bulky Nucleophile/Base favor Elimination High Temperature favors Elimination We know- This equation says that a reaction in which ΔS is positive is more thermodynamically favorable at higher temperature. Eliminations should therefore be favoured at high temperature Keep in Mind---- Mechanism Classification E1 Mechanism- Elimination Unimolecular E1 describes an elimination reaction (E) in which the rate-determining step is unimolecular (1) and does not involve the base. The leaving group leaves in this step, and the proton is removed in a separate second step E2 Mechanism- Elimination Bimolecular E2 describes an elimination (E) that has a bimolecular (2) rate-determining step that must involve the base. Loss of the leaving group is simultaneous with removal of the proton by the base Bulky t-butoxide—ideal for promoting E2 as it’s both bulky and a strong base (pKaH = 18). Other Organic Base used in Elimination Reaction These two bases are amidines—delocalization of one nitrogen’s lone pair on to the other, and the resulting stabilization of the protonated amidinium ion, E1 can occur only with substrates that can ionize to give relatively stable carbocations—tertiary, allylic or benzylic alkyl halides, for example. E1-Elimination Reaction not possible here The role of the leaving group Since the leaving group is involved in the rate-determining step of both E1 and E2, in general, any good leaving group will lead to a fast elimination. -
1 Abietic Acid R Abrasive Silica for Polishing DR Acenaphthene M (LC
1 abietic acid R abrasive silica for polishing DR acenaphthene M (LC) acenaphthene quinone R acenaphthylene R acetal (see 1,1-diethoxyethane) acetaldehyde M (FC) acetaldehyde-d (CH3CDO) R acetaldehyde dimethyl acetal CH acetaldoxime R acetamide M (LC) acetamidinium chloride R acetamidoacrylic acid 2- NB acetamidobenzaldehyde p- R acetamidobenzenesulfonyl chloride 4- R acetamidodeoxythioglucopyranose triacetate 2- -2- -1- -β-D- 3,4,6- AB acetamidomethylthiazole 2- -4- PB acetanilide M (LC) acetazolamide R acetdimethylamide see dimethylacetamide, N,N- acethydrazide R acetic acid M (solv) acetic anhydride M (FC) acetmethylamide see methylacetamide, N- acetoacetamide R acetoacetanilide R acetoacetic acid, lithium salt R acetobromoglucose -α-D- NB acetohydroxamic acid R acetoin R acetol (hydroxyacetone) R acetonaphthalide (α)R acetone M (solv) acetone ,A.R. M (solv) acetone-d6 RM acetone cyanohydrin R acetonedicarboxylic acid ,dimethyl ester R acetonedicarboxylic acid -1,3- R acetone dimethyl acetal see dimethoxypropane 2,2- acetonitrile M (solv) acetonitrile-d3 RM acetonylacetone see hexanedione 2,5- acetonylbenzylhydroxycoumarin (3-(α- -4- R acetophenone M (LC) acetophenone oxime R acetophenone trimethylsilyl enol ether see phenyltrimethylsilyl... acetoxyacetone (oxopropyl acetate 2-) R acetoxybenzoic acid 4- DS acetoxynaphthoic acid 6- -2- R 2 acetylacetaldehyde dimethylacetal R acetylacetone (pentanedione -2,4-) M (C) acetylbenzonitrile p- R acetylbiphenyl 4- see phenylacetophenone, p- acetyl bromide M (FC) acetylbromothiophene 2- -5- -
(12) Patent Application Publication (10) Pub. No.: US 2005/0044778A1 Orr (43) Pub
US 20050044778A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2005/0044778A1 Orr (43) Pub. Date: Mar. 3, 2005 (54) FUEL COMPOSITIONS EMPLOYING Publication Classification CATALYST COMBUSTION STRUCTURE (51) Int. CI.' ........ C10L 1/28; C1OL 1/24; C1OL 1/18; (76) Inventor: William C. Orr, Denver, CO (US) C1OL 1/12; C1OL 1/26 Correspondence Address: (52) U.S. Cl. ................. 44/320; 44/435; 44/378; 44/388; HOGAN & HARTSON LLP 44/385; 44/444; 44/443 ONE TABOR CENTER, SUITE 1500 1200 SEVENTEENTH ST DENVER, CO 80202 (US) (57) ABSTRACT (21) Appl. No.: 10/722,127 Metallic vapor phase fuel compositions relating to a broad (22) Filed: Nov. 24, 2003 Spectrum of pollution reducing, improved combustion per Related U.S. Application Data formance, and enhanced Stability fuel compositions for use in jet, aviation, turbine, diesel, gasoline, and other combus (63) Continuation-in-part of application No. 08/986,891, tion applications include co-combustion agents preferably filed on Dec. 8, 1997, now Pat. No. 6,652,608. including trimethoxymethylsilane. Patent Application Publication Mar. 3, 2005 US 2005/0044778A1 FIGURE 1 CALCULATING BUNSEN BURNER LAMINAR FLAME VELOCITY (LFV) OR BURNING VELOCITY (BV) CONVENTIONAL FLAME LUMINOUS FLAME Method For Calculating Bunsen Burner Laminar Flame Velocity (LHV) or Burning Velocity Requires Inside Laminar Cone Angle (0) and The Gas Velocity (Vg). LFV = A, SIN 2 x VG US 2005/0044778A1 Mar. 3, 2005 FUEL COMPOSITIONS EMPLOYING CATALYST Chart of Elements (CAS version), and mixture, wherein said COMBUSTION STRUCTURE element or derivative compound, is combustible, and option 0001) The present invention is a CIP of my U.S. -
[3+2]-ANNULATION REACTIONS with NITROALKENES in the SYNTHESIS of AROMATIC FIVE-MEMBERED NITROGEN HETEROCYCLES Vladimir A. Motorn
237 [3+2] - ANNULATION REACTIONS WIT H NITROALKENES IN THE SYNTHESIS OF AROMATIC FIVE - MEMBERED NITROGEN HETEROCYCLES DOI: http://dx.medra.org/ 10.17374/targets.2020.23.2 37 Vladimir A. Motornov, Sema L. Ioffe, Andrey A. Tabolin * N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky prosp. 47, 119991 Moscow, Russia (e - mail: [email protected]) Abstract. [3+2] - A nnulation reactions are widely used for the synthesis of aromatic heterocycles. In recent years they have become attractive for the preparation of medicinally relevant heterocycles due to their broad substrate scope and availability of starting materials . A nnulations with nitroalkenes may lead to different products due to the ability of the nitro - group to act both as activating group and as leaving group. Ultimately this gives rise to the synthesis of multifunctional heterocyclic compounds, including nitro - substituted ones. The present review covers various annulation re actions with nitroalkenes leading to five - membered nitrogen - containing heterocyclic rings. Oxidative annulation, annulation/elimination and self - oxidative annulation pathways are discussed. Contents 1. Introduction 2. Classification of nitroalkene - b ased annulation reactions 3. A nnulations with nitroalkenes in the synthesis of five - membered rings 3.1. Synthesis of pyrroles 3.1.1. Barton - Zard pyrrole synthesis 3.1.2. Annulation with enamines 3.1.3. Annulation with azomethine ylides 3.2. Synthesis of pyrazoles 3.2.1. Nitroalkene - diazo comp o unds [3+2] - cycloadditions 3.2.2. Oxidative annulation of nitroalkenes with hydrazones 3.3. Synthesis of imidazoles and imidazo[1,2 - a]pyridines 3.4. Synthesis of indolizines and related heter ocycles 3.5. -
SOM KINETIC STUDIES OH KETONE FORMATION THESIS Submitted for the Degree of Doctor of Philosophy at Glasgow University Hy Margare
S O M KINETIC STUDIES OH KETONE FORMATION THESIS submitted for the Degree of Doctor of Philosophy at Glasgow University hy Margaret Bennett Thornley May, 1956 Supervisor Dr. R. I. Reed. ProQuest Number: 13848948 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest ProQuest 13848948 Published by ProQuest LLC(2019). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 4 8 1 0 6 - 1346 TABLE OF CONTENTS. Page. SUMMARY. 2 Part I. HISTORICAL INTRODUCTION. 5 EXPERIMENTAL RESULTS. 13 Comparison of Reaction Rates in Different Media. 8® THEORETICAL INTERPRETATION OP RESULTS. S3 KINETIC OBSERVATIONS. 38 Dilatometry. 35 Colorimetric Estimation. 39 Chemical Analysis. 40 Experimental Determination. 43 Specimen Results. 44 Dieckmann Ring Closure of Diethyl Pimelate. 46 FORMAL PROOF OF UNIQUE RING FORMATION. 50 Experimental Procedure. 53 PREPARATIVE WORK. 55 Part II. HISTORICAL SURVEY. 59 PRELIMINARY EXPERIMENTAL WORK. 69 Preparation and Analysis of Sodium Salts. 71 KINETIC OBSERVATIONS. 74 Experimental Method. 75 Specimen Results. 76 EXPERIMENTAL RESULTS. 81 Page. EXPERIMENTAL RESULTS. 81 Mathematical Analysis. 82 Effect of Nature of Reaction Vessel. 86 To Investigate the Effect of Reaction Products. 89 Pyrolysis of Disodium (3-methyladipate. -
Reactions of Aromatic Compounds Just Like an Alkene, Benzene Has Clouds of Electrons Above and Below Its Sigma Bond Framework
Reactions of Aromatic Compounds Just like an alkene, benzene has clouds of electrons above and below its sigma bond framework. Although the electrons are in a stable aromatic system, they are still available for reaction with strong electrophiles. This generates a carbocation which is resonance stabilized (but not aromatic). This cation is called a sigma complex because the electrophile is joined to the benzene ring through a new sigma bond. The sigma complex (also called an arenium ion) is not aromatic since it contains an sp3 carbon (which disrupts the required loop of p orbitals). Ch17 Reactions of Aromatic Compounds (landscape).docx Page1 The loss of aromaticity required to form the sigma complex explains the highly endothermic nature of the first step. (That is why we require strong electrophiles for reaction). The sigma complex wishes to regain its aromaticity, and it may do so by either a reversal of the first step (i.e. regenerate the starting material) or by loss of the proton on the sp3 carbon (leading to a substitution product). When a reaction proceeds this way, it is electrophilic aromatic substitution. There are a wide variety of electrophiles that can be introduced into a benzene ring in this way, and so electrophilic aromatic substitution is a very important method for the synthesis of substituted aromatic compounds. Ch17 Reactions of Aromatic Compounds (landscape).docx Page2 Bromination of Benzene Bromination follows the same general mechanism for the electrophilic aromatic substitution (EAS). Bromine itself is not electrophilic enough to react with benzene. But the addition of a strong Lewis acid (electron pair acceptor), such as FeBr3, catalyses the reaction, and leads to the substitution product. -
Elimination Reactions Are Described
Introduction In this module, different types of elimination reactions are described. From a practical standpoint, elimination reactions widely used for the generation of double and triple bonds in compounds from a saturated precursor molecule. The presence of a good leaving group is a prerequisite in most elimination reactions. Traditional classification of elimination reactions, in terms of the molecularity of the reaction is employed. How the changes in the nature of the substrate as well as reaction conditions affect the mechanism of elimination are subsequently discussed. The stereochemical requirements for elimination in a given substrate and its consequence in the product stereochemistry is emphasized. ELIMINATION REACTIONS Objective and Outline beta-eliminations E1, E2 and E1cB mechanisms Stereochemical considerations of these reactions Examples of E1, E2 and E1cB reactions Alpha eliminations and generation of carbene I. Basics Elimination reactions involve the loss of fragments or groups from a molecule to generate multiple bonds. A generalized equation is shown below for 1,2-elimination wherein the X and Y from two adjacent carbon atoms are removed, elimination C C C C -XY X Y Three major types of elimination reactions are: α-elimination: two atoms or groups are removed from the same atom. It is also known as 1,1-elimination. H R R C X C + HX R Both H and X are removed from carbon atom here R Carbene β-elimination: loss of atoms or groups on adjacent atoms. It is also H H known as 1,2- elimination. R C C R R HC CH R X H γ-elimination: loss of atoms or groups from the 1st and 3rd positions as shown below. -
Art-Of-Drugs-Synthesis.Pdf
THE ART OF DRUG SYNTHESIS THE ART OF DRUG SYNTHESIS Edited by Douglas S. Johnson Jie Jack Li Pfizer Global Research and Development Copyright # 2007 by John Wiley & Sons, Inc. All rights reserved. Published by John Wiley & Sons, Inc., Hoboken, New Jersey Published simultaneously in Canada No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 750-4470, or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008, or online at http://www.wiley.com/go/permission. Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate. -
REARRANGEMENTS of ALLENES and ACETYLENES by MICHAEL
REARRANGEMENTS OF ALLENES AND ACETYLENES by MICHAEL McPHERSON Thesis submitted for the degree of Doctor of Philosophy University of Edinburgh 1983 I ,•,1. tTAI Acknowledgements I would like to thank Dr. I.H. Sadler for his assistance and encouragement, and the Staff and Technical Staff of the Chemistry Department for their assistance throughout the period of this work. I also wish to thank my parents for their support and encouragement. Finally I wish to thank Mrs. C.G. Ranken for her excellent typing of this thesis. Abstract of Thesis This thesis describes the preparation of alkynyl derivatives of fluorene via reaction of the fluorenyl anion (generated with phenyl lithium) with alkynyl halides. Low pressure vapour phase pyrolysis of these compounds was carried out. Propargylic fluorenes gave allenyl fluorenes by an intramolecular sigmatropic shift with other, radical derived, products predominating at higher temperatures.. The alkynyl fluorenes were themselves resistant to rearrangement by base but the allenyl fluorenes rearranged readily on alumina to give dibenzofulvenes. A number of alkynyl derivatives of indene were prepared by first generating the indenyl anion with sodamide in liquid ammonia or by aqueous alkali under phase transfer catalysis conditions. The anion thus generated was then. reacted with alkynyl halides. Propargylic indenes gave allenyl indenes on pyrolysis and it is shown that the allenes are produced by an intramolecular sigmatropic. shift or a 'Cope' rearrangement depending on the nature of the alkynyl indene. The alkynyl indenes rearrange by base to give benzofulvenes. The benzo- fulvenes were produced as mixtures of geometric isomers some of which were separable. The individual isomers or mixtures of isomers were characterised largely by use of high field 'H n.m.r. -
Elimination Reaction
Elimination reaction An elimination reaction is a type of organic reaction in which two substituents are removed from a molecule in either one or two-step mechanism.[2] The one-step mechanism is known as the E2 reaction, and the two-step mechanism is known as the E1 reaction. The numbers refer not to the number of steps in the mechanism, but rather to the kinetics of the reaction: E2 is Elimination reaction of cyclohexanol to bimolecular (second-order) while E1 is unimolecular (first-order). cyclohexene with sulfuric acid and In cases where the molecule is able to stabilize an anion but heat[1] possesses a poor leaving group, a third type of reaction, E1CB, exists. Finally, the pyrolysis of xanthate and acetate esters proceed through an "internal" elimination mechanism, the Ei mechanism. Contents Loss of hydron (H+) E2 mechanism E1 mechanism Competition among mechanisms Elimination reactions other than β-elimination See also References External links Loss of hydron (H+) In most organic elimination reactions, at least one hydron (H+) is lost to form the double bond: the unsaturation of the molecule increases. It is also possible that a molecule undergoes reductive elimination, by which the valence of an atom in the molecule decreases by two, though this is more common in inorganic chemistry. An important class of elimination reactions is those involving alkyl halides, with good leaving groups, reacting with a Lewis base to form an alkene. Elimination may be considered the reverse of an addition reaction. When the substrate is asymmetric, regioselectivity is determined by Zaitsev's rule or through Hofmann elimination if the carbon with the most substituted hydrogen is inaccessible. -
'({JIXOAA* Laiuoaim ' ' " Adviser Department of Chemistry DEDICATION
SYNTHESIS AND REACTIONS OF INTERMEDIATES FOR STEROID ELABORATION DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Arlen B. Mekler, B.S., M.S. • • • o o The Ohio State University 1959 Approved by '({JIXOAA* lAiUOAim ' ' " Adviser Department of Chemistry DEDICATION TO LEV A. MEKLER ii ACKNOWLEDGMENT The author wishes to express his sincere appreciation to Dr. Melvin S. Newman for stimulating ideas and helpful advice, for interesting discussions and constructive criticisms, for invaluable laboratory techniques, for his personal friendship and his inspirational guidance throughout this research. The author is also grateful for the receipt of the following awards: Charles P. Kettering Founda tion Fellowship, 1956-1957; Melvin S. Newman Scholarship, 1957; U. S. Industrial Company Fellow ship, 1957-1958; Allied Chemical Company Fellowship, 1958-1959; and E. I. Du Pont Research Fellowship, 1959. iii TABLE OP CONTENTS Page ACKNOWLEDGMENT. ... .. ill OBJECTIVE 1 HISTORICAL BACKGROUND 4 DISCUSSION OP RESULTS 20 SUGGESTIONS FOR FURTHER WORK 39 EXPERIMENTAL «,.... 42 General Procedures, 42 2-Methyl-l, 3-cyclohexanedione 43 4-Diethylamino-3-butanone0 44 1,6-Dioxo-8a-methyl-l, 2, 3, 4, 6,7,8, 8a- oc tahydronaphthalene. ••• 44 K -(6-Methyl-3-keto-l-cyclohexene- 1-yl)-butyric acid 47 Methyl ^-(6-Methyl-3-keto-l-cyclo- hexene-1-yl) butyrate • 48 Methyl &"-(3-Acetoxy-6-methyl-l,3- cyclohexadien-1-yl) butyrate. 49 Methyl #-( 5-Hydroxy-2-methylphenyl) - butyrate 50 Action of Sodium Methoxide on Methyl ^-{ 5-Hydroxy-2-methylphenyl) butyrate 51 3- (4-Hydroxybutyl) - 4-me thylphenol 51 3- ( 4-Bromobutyl) - 4-me thylphenol • 52 Attempted Synthesis of 3-(4-bromobutyl)- 4-Methylphenol Employing Acetic Acid. -
Elimination Reactions
Elimination Reactions Elimination reactions discussed here are reactions that produce alkenes, usually from the loss of two particles, x-y, from a substrate. The nucleophilic substitution reactions discussed in another section are often accompanied by elimination reactions as competing reactions. Conditions can be met that make the elimination reaction the main reaction. Fluorine can be eliminated as fluoride but it is the least reactive of the halogens because of its strong C-F bond. Thus for halogens the rate of elimination is I>Br>Cl>F. Fluorine, because of its great electronegativity, can cause the beta hydrogen to become acidic. The mechanism of elimination form many fluorinated compounds involves a carbanion in the E1cb (Elimination first order carbanion) mechanism. Stereoselectiviy of elimination is not always observed. Elimination first order (E1) Secondary substrates give products from both substitution and elimination, by first rate limiting ionization of the substrate to produce a carbocation. The carbocation then can react with a nucleophile (SN1) or lose a beta hydrogen (E1) to form an alkene. Of course, carbocations can do other things such as rearrange to a more stable carbocation followed by substitution and elimination. The E1 mechanism is unlikely for fluorinated compounds because of the requirement to break the strong carbon-fluorine bond in the rate determining step. CH3 H Ph OCH3 Racemic mixture SN1 CH3 CH3OH H H CH3 Ph I Ph E1 R enantiomer a carbocation H CH2 Ph The elimination reactions requires removal of a beta hydrogen by a base. Thus increasing the base strength of the reaction medium increases the amount of elimination product.