Ebook A Handbook of spectroscopic data chemistry Part 1

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Ebook A Handbook of spectroscopic data chemistry Part 1

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(BQ) Part 1 book A Handbook of spectroscopic data chemistry has contents: Ultraviolet spectroscopy, infrared spectroscopy, proton magnetic resonance spectroscopy. Please refer to the content. BQ) Part 1 book A Handbook of spectroscopic data chemistry has contents: Ultraviolet spectroscopy, infrared spectroscopy, proton magnetic resonance spectroscopy. Please refer to the content.

A Handbook of Spectroscopic Data CHEMISTRY (UV, JR, PMR, JJCNMR and Mass Spectroscopy) B.D Mistry B.K.M Science College Va/sad - (Gujarat) Oxford Book Company Jaipur, India ISBN: 978-81-89473-86-0 Edition 2009 Oxford Book Company 267, 10-B-Scheme Opp Narayan Niwas, Gopalpura By Pass Road, Jaipur-302018 Phone: 0141-2594705, Fax: 0141-2597527 e-mail: oxfordbook@sify.com website: www.oxfordbookcompany.com © Reserved Typeset by: Shivangi Computers 267, lO-B-Scheme, Opp Narayan Niwas Gopalpura By Pass Road, Jaipur-302018 Printed at : Mehra Offset Printers, Delhi All Rights are Reserved 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, without the prior \HItten permission of the copyright owner Responsibility for the facts stated opinions expressed, conclusions reached and plagiarism, if any, in this volume is entirely that of the Author, according to whom the matter encompassed in this book has been originally created/edited and resemblance with any such publication may be incidental The Publisher bears no responsibility for them, whatsoever Contents Ultraviolet Spectroscopy Infrared Spectroscopy Proton Magnetic Resonance Spectroscopy Be NMR Spectroscopy Mass Spectrometry Structural Data Obtainable from Different Spectra Index 26 64 99 128 237 240 "This page is Intentionally Left Blank" Ultraviolet Spectroscopy 1.1 Calculating Absorption Maxima of Unsaturated Compounds Dienes and trienes : If the compound is suspected to be a conjugated or substituted diene, its wavelength of maximum absorption can be predicted with the help of Table I I To be able to use this table, one must first learn to recognize different types of dienes, conjugations, double bonds, etc These are as follows: c=c< _ ) C=C< A linear conjugation; for example, 1,3,5 C-C hexatriene, isoprene,etc ) C=C< A cross conjugation ii) )C=C )C=C< i) ) iii) iv) o o A cyclic diene; for example, cyclohexadiene, cyclohepta 1,3- diene, etc A semicyclic diene; one of the double bonds forms part of a ring and the other is exocyclic, or outside the ring When only one of of the two Sp2 hybridized carbons of a double bond is a part of the ring under Spectroscopic Data Chemistry consideration, such a double bond is called an exocycIic double bond A homoannular diene is one in which the v) two double bonds are conjugated and are in a single ring Note that both double bonds are exocycIic to ring B vi) A heteroannular diene is a conjugated system in which the two double bonds belong to two different rings However, these double bonds are also exocycIic, one of them being exoto ring A and the other exo-to ring B Table 1.1: Woodward's and Fieser's rules for Diene absorption (ethanol solution) i) Base value for an unsubstituted, conjugated, acyclic or heteroannular diene ii) 214 nm Base value for an unsubstituted, conjugated homoannular diene 253 nm Increments for iii) Extra double bonds in conjugation (for each C=C) +30 nm iv) ExocycIic double bond (effect is two fold ifbond is exocylic to two rings) v) +5nm Substitutents on Sp2 hybridised carbon atom, per substituent a) O-acyl (-O-CO-R or -O-CO-Ar) Onm b) Simple alkyl (-R) or ring residue +5nm c) Halogen (-CI, -Br) +5nm d) O-alkyl (-OR) +6nm e) S-alkyl (-SR) +30nm f) N-alkyl, (-NRR ') + 60 nm vi) Solvent correction Onm Ultraviolet Spectroscopy , The following points are to be noted: • The cyclic homoannular base values refer to a six membered ring only For other rings the values are: Five membered ring (C s) 228 nm Seven membered ring (C ) 241 nm • Accuracy of prediction is ± nm • If there is more than one possibility for calculating Amax, the highest Amax value usually agrees with the observed value Limitations • Agreement is quite good for acyclic and six-membered ring polyenes but not so for other rings in some cases • Steric strain can also affect the position (Amax) of the band, sometimes very greatly if the strain is high A simple example of this is 1,2 dimethylene cyclohexane, which gives a strong UV band at Amax 220 nm (E 10,050) which is quite different from the calcualted value Polyenes : The above rules (Table 1.1) holds fairly well for unsaturated compounds containing up to four conjugated double bonds However, for systems of extended conjugation, such as those found in carotenoid pigments, Fieser and Kuhn have suggested equations to calculate the basic Amax and Em ofUV absorption Amax (in hexane) = 114 + 5M + n (48.0 - 1.7n) -I 5Rendo - IOR exo E ma , (in hexane) = 1.74 x 104n Where n = number of conjugated double bonds M = number of alkyl or alkyl like substituents on the conjugated system Rendo = number of rings with endocyclic double bonds in the conjugated system Rexo = 1.2 number of rings with exocyclic double bonds Calculating Absorption Maxima of Carbonyl Compounds The basic chromophore containing a >C=C< ( ene) conjugated with a >c=o (-one), as in Spectroscopic Data Chemistry P a > C = C- C = IS called an enone If a carbonyl group is conjugated with two double bonds (-cliene), such as Ii y P a >C=C-C = C-C = The compound is known as a dienone In the case of cyclic compounds, the ethylenic double bonds conjugated with the carbonyl may be homoannular or heteroannular Table 1.2: Rules of Enone and Dienone absorption P- paZ y paZ I I I I I I I I C = C - C = and - C = C - C = C - C = Enone Dienone Z = C, enone, Z = H, aldehyde Z = OH, acid, Z = OR, ester Parent enone (acyclic or rings larger than members) 5-membered cyclic enone Aldehydes Acid and Esters Increments for Double bond extending conjugation (for eacb one) Homodiene component Exocyclic double bond (or any >C=C< endocyclic to 5- or 7member ring in a case of acid and ester) Alkyl group, ring residue a p 215nm 205nm 210nm 195nm +30nm +39nm +5nm +IOnm +12nm y Hydroxyl (-OH) Alkoxyl (-OCH 3) and higher +ISnm a +35nm p +30nm y a y 50nm +35nm +30nm + 17nm o 31nm p Ultraviolet Spectroscopy Acetoxyl (-O-COCH ) Dialkyl aniino (-NR) Chlorine (-CI) a, ~ or

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