...2001, and then fully described by Hartmuth Kolb, Sharpless, and M.G. Finn. A desirable click reaction should fulfill the criteria including modular, wide in scope, high chemical yields, stereospecific, simple to perform, simple reaction conditions, inoffensive byproducts, physiologically stable, readily accessible reagents, and easily removable or benign solvents etc. It was identified that several types of reactions can satisfy these prerequisites, such as addition to carbon-carbon multiple bond (e.g. Michael Additions, oxidative formation of epoxides), non-aldol type carbonyl reactions (e.g. formation of heterocycles and hydrazones), and cycloaddition reactions....
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...In this experiment, a Diels-Alder cycloaddition reaction was performed. This reaction was performed with 1,3-cyclopentadiene and maleic anhydride. The 1,3-cyclopentadiene was obtained by cracking dicyclopentadiene. The Diels-Alder reaction resulted in 2.0881 grams of clear white crystals, which were confirmed to be cis-norbornene-5,6-endo-dicarboxylicacid anhydride. This amount determined a percent yield of 83.16 %. The percent yield is only 83.16 % because some product was lost during vacuum filtration. This loss could have been prevented by using colder water to transfer the crystals. The retrieve all of the crystals out of the flask, cool water was used. This caused some of the crystal dissolved and pass through the filter. The use of colder waster would prevent the crystals from dissolving. However, the amount that was lost was minimal, and the identification of the product was still confirmed by melting point, IR, and NMR. The melting point for the product was found to be 164-166 ˚C. This range coincides with the...
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...The experiment involved a Diel-Alder reaction and is also known as a [4+2] cycloaddition because the reaction takes place between two different π Systems, one of which is associated with 4 atoms and the other one having two atoms. We synthesized 9,10-dihydroanthracene-9,10α,β 13-succinic acid anhydride from anthracene (diene) and meleic anhydride (dienophile). The use of maleic anhydride as the dienophile allows for a relatively high yield because the carbonyl substituents remove electron density from the reactive site through resonance and ultimately lowers the energy of the lowest unoccupied molecular orbital of the maleic acid anhydride molecule. By using anthracene as the diene, the conjugated π bonds are able to donate electron density...
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...Synthesis of the Diels-Alder Adduct Purpose: To investigate the methods behind Diels-Alder chemistry through the laboratory synthesis of 4- cyclohexene-cis- ,2-dicarboxylic anhydride from butadiene sulfone with maleic anhydride. By utilizing the theoretical concepts in a hands-on approach through laboratory synthesis, I hope to gain a better understanding of the reaction concepts governing Diels- Alder chemistry. Theory: The Diels-Alder reaction is a cycloaddition, chemical reaction that occurs between a conjugated diene, a molecule with two alternating double bonds, and dienophile, an alkene, to form rings and bicyclic compounds. Because it involves the interaction of four π electrons that are supplied by the diene and the two π electrons supplied by the dienophile, the Diels-Alder reaction is often called [4 + 2] cycloaddition. In the reaction, two new σ bonds are formed and one π bond is formed at the expense of two π bonds, which results in a cyclic product. The Diels-Alder reaction is a member of a larger class of reactions called pericylic reactions, which are reactions that take place in a single step, without intermediates and that involve the flow or redistribution of bonding electrons. The reaction proceeds through a cyclic transition state and is concerted, meaning bonds in the transition state are simultaneously made or broken. The Diels-Alder reaction is favored when the dienophile is the substituted with electron withdrawing groups such as nitriles, amines...
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...The Diels-Alder Reaction of Anthracene with Maleic Anhydride The Diels-Alder reaction is a member of a class of reactions called cycloadditions. The reaction involves three π bonds, two from the diene and one from the dienophile in a concerted reaction to form a six-membered ring. Since the reaction involves four π electrons in the diene and two π electrons from the dienophile, it is sometimes referred to as a 4 + 2 cycloaddition. Normal Diels-Alder reactions are favored by electron donating groups on the diene and electron withdrawing groups on the dienophile. The diene must be capable of achieving an s-cis conformation to generate the cis double bond in the cyclohexene product. Acyclic dienes may rotate around a single bond, but dienes locked in the s-trans conformation do not react. [pic] The purpose of this experiment is to form 9,10-dihydroanthracene-9,10-α,β-succinic anhydride by way of a Diels Alder reaction between anthracene and maleic anhydride, as shown in the reaction below. Anthracene acts as the diene and maleic anhydride functions as the dienophile. Xylene (dimethylbenzene) is used as a high boiling temperature solvent so that the reaction will proceed quickly. Melting temperature analysis will be used to characterize the product. Anthracene Maleic anhydride 9,10-dihydroanthracene- ...
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...[4 + 2] cycloaddition reactions have been a valuable research topic for scientists for some time now. More specifically, the combination of dienes and carbonyl containing compounds have been studied primarily for their ability to combine together to form six membered oxygen heterocycles (1). The synthesis of oxygen heterocycles is a valuable tool, as these molecules are precursors to some natural products and they are also components in the synthesis of various carbohydrates (4). The general method utilized to form oxygen heterocycles was to combine an aldehyde as the heterodienophile and a diene in a hetero-Diels-Alder reaction. Extensive studies on this reaction have been completed. Huang and Rawal chose to study this reaction using hydrogen bond promoted ketones as the heterodienophile rather than aldehydes. This is the first time that unactivated ketones have been successfully utilized in a hetero-Diels-Alder reaction. This research is extremely valuable as it expands the extent by which oxygen heterocycles can be formed. This is extremely important to the biological chemists who study and utilize oxygen heterocycles frequently (1). Huang and Rawal began their study by observing the hetero-Diels Alder reaction rates between various aldehydes and the diene 1-amino-3-siloxybuadiene. They found that the reaction rate was siginificantly higher in polar protic solvents rather than polar aprotic solvents (2). They attributed this change in the reaction rate to...
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...Organic Chemistry Second Edition The INSTANT NOTES series Series Editor: B.D. Hames School of Biochemistry and Molecular Biology, University of Leeds, Leeds, UK Animal Biology 2nd edition Biochemistry 2nd edition Bioinformatics Chemistry for Biologists 2nd edition Developmental Biology Ecology 2nd edition Immunology 2nd edition Genetics 2nd edition Microbiology 2nd edition Molecular Biology 2nd edition Neuroscience Plant Biology Chemistry series Consulting Editor: Howard Stanbury Analytical Chemistry Inorganic Chemistry 2nd edition Medicinal Chemistry Organic Chemistry 2nd edition Physical Chemistry Psychology series Sub-series Editor: Hugh Wagner Dept of Psychology, University of Central Lancashire, Preston, UK Psychology Forthcoming titles Cognitive Psychology Physiological Psychology Organic Chemistry Second Edition G. L. Patrick Department of Chemistry and Chemical Engineering, Paisley University, Paisley, Scotland This edition published in the Taylor & Francis e-Library, 2005. "To purchase your own copy of this or any of Taylor & Francis or Routledge's collection of thousands of eBooks please go to www.eBookstore. tandf.co.uk.” © Garland Science/BIOS Scientific Publishers, 2004 First published 2000 Second edition published 2004 All rights reserved. No part of this book may be reproduced or transmitted, in any form or by any means, without permission. A CIP catalogue record for this book is available from the British Library. ISBN 0-203-42761-0 Master e-book...
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...ate Aptitude Test in Engineering GATE 2014 Brochure Table of Contents 1. Introduction .............................................................................................................1 2. About GATE 2014 ......................................................................................................1 2.1. Financial Assistance ............................................................................................................................ 1 2.2 Employment ............................................................................................................................................ 2 2.3 Administration ....................................................................................................................................... 2 3.1 Changes Introduced in GATE 2013 that will continue to remain in force for GATE 2014 .......................................................................................................................................................... 3 4.1 Eligibility for GATE 2014 ................................................................................................................... 4 4.2 GATE Papers ............................................................................................................................................ 5 4.3 Zone-Wise List of Cities in which GATE 2014 will be Held ................................................... 6 4.4 Zone-Wise List of Cities for 3rd...
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...Employment News 31 May - 6 June 2014 www.employmentnews.gov.in 21 UNION PUBLIC SERVICE COMMISSION EXAMINATION NOTICE NO. 09/2014-CSP (LAST DATE FOR RECEIPT OF APPLICATIONS : 30/06/2014) DATE :31.05.2014 CIVIL SERVICES EXAMINATION, 2014 (Commission’s website-http://upsc.gov.in) F. No. 1/5/2013-E.I(B) : Preliminary Examination of the Civil Services Examination for recruitment to the Services and Posts mentioned below will be held by the Union Public Service Commission on 24th Aug., 2014 in accordance with the Rules published by the Department of Personnel & Training in the Gazette of India Extraordinary dated 31st May, 2014. (i) Indian Administrative Service. (ii) Indian Foreign Service. (iii) Indian Police Service. (iv) Indian P & T Accounts & Finance Service, Group ‘A’. (v) Indian Audit and Accounts Service, Group ‘A’. (vi) Indian Revenue Service (Customs and Central Excise), Group ‘A’. (vii) Indian Defence Accounts Service, Group ‘A’. (viii) Indian Revenue Service (I.T.), Group ‘A’. (ix) Indian Ordnance Factories Service, Group ‘A’ (Assistant Works Manager, Administration). (x) Indian Postal Service, Group ‘A’. (xi) Indian Civil Accounts Service, Group ‘A’. (xii) Indian Railway Traffic Service, Group ‘A’. (xiii) Indian Railway Accounts Service, Group 'A'. (xiv) Indian Railway Personnel Service, Group ‘A’. (xv) Post of Assistant Security Commissioner in Railway Protection Force, Group ‘A’ (xvi) Indian Defence Estates Service, Group...
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...Employment News 11 - 17 February 2012 www.employmentnews.gov.in 21 Union Public Service Commission EXAMINATION NOTICE NO. 04/2012-CSP DATED 11.02.2012 (LAST DATE FOR RECEIPT OF APPLICATIONS : 05.03.2012) CIVIL SERVICES EXAMINATION, 2012 (Commission's website - http://www.upsc.gov.in) F. No. 1/4/2011-E.I(B) : Preliminary Examination of the Civil Services Examination for recruitment to the Services and Posts mentioned below will be held by the Union Public Service Commission on 20th May, 2012 in accordance with the Rules published by the Department of Personnel & Training in the Gazette of India Extraordinary dated 4th February, 2012. (i) Indian Administrative Service. (ii) Indian Foreign Service. (iii) Indian Police Service. (iv) Indian P & T Accounts & Finance Service, Group ‘A’. (v) Indian Audit and Accounts Service, Group ‘A’. (vi) Indian Revenue Service (Customs and Central Excise), Group ‘A’. (vii) Indian Defence Accounts Service, Group ‘A’. (viii) Indian Revenue Service (I.T.), Group ‘A’. (ix) Indian Ordnance Factories Service, Group ‘A’ (Assistant Works Manager, Administration). (x) Indian Postal Service, Group ‘A’. (xi) Indian Civil Accounts Service, Group ‘A’. (xii) Indian Railway Traffic Service, Group ‘A’. (xiii) Indian Railway Accounts Service, Group 'A'. (xiv) Indian Railway Personnel Service, Group ‘A’. (xv) Post of Assistant Security Commissioner in Railway Protection Force, Group ‘A’ (xvi) Indian Defence Estates Service, Group ‘A’. (xvii) Indian Information...
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