Structure Determination of Organic Compounds: Tables of Spectral Data [5 ed.] 9783662624395, 3662624397

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Ernö Pretsch Philippe Bühlmann Martin Badertscher

NMR MS UV/Vis IR

Structure Determination of Organic Compounds Tables of Spectral Data Fifth Edition

Structure Determination of Organic Compounds

Ernö Pretsch • Philippe Bühlmann Martin Badertscher

Structure Determination of Organic Compounds Tables of Spectral Data Fifth Edition

Ernö Pretsch Institute of Biogeochemistry and Pollutant Dynamics ETH Zurich Zürich, Switzerland

Philippe Bühlmann Department of Chemistry University of Minnesota Minneapolis, MN, USA

Martin Badertscher Laboratory of Organic Chemistry ETH Zurich Zürich, Switzerland

Translation from the German language edition: Spektroskopische Daten zur Strukturaufklärung organischer Verbindungen by Ernö Pretsch, Philippe Bühlmann, Martin Badertscher Copyright © Springer-Verlag GmbH Deutschland, ein Teil von Springer Nature 1976, 1981, 1986, 2001, 2010, 2020. Published by Springer Spektrum. All Rights Reserved. ISBN 978-3-662-62438-8 ISBN 978-3-662-62439-5 (eBook) https://doi.org/10.1007/978-3-662-62439-5 © Springer-Verlag GmbH Germany, part of Springer Nature 2020 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer-Verlag GmbH, DE part of Springer Nature. The registered company address is: Heidelberger Platz 3, 14197 Berlin, Germany

Preface

We present in this volume an updated collection of reference data and rules for the interpretation of spectra obtained with the spectroscopic methods most important to the structure elucidation of organic compounds: NMR spectroscopy (1H, 13C, 15N, 19F, 29Si, and 31P), mass spectrometry (EI-MS and ESI-MS/MS), and IR, Raman and UV/Vis spectroscopy. The basic idea is that a simultaneous application of several of these techniques is much more powerful than even the most sophisticated analysis of only one kind of spectrum. The ongoing success of our combined approach corroborates its utility. This new edition contains numerous new data added to existing tables and figures. Additionally, we extended the scope of this volume taking into account new developments in instrumentation. We added novel collections of reference data for the interpretation of 15N and 29Si NMR spectra. The careful selection of relevant information from across the literature seems to be unique in these fields. An important recent development is the routine MS/MS analysis after soft ionization (mainly ESI and MALDI). For this volume, we supplemented the existing fragmentation rules for EI by rules for MS/MS analysis after soft ionization. We thank Dr. Csaba Szántay und Áron Szigetvári (Spectroscopic Research Department, Gedeon Richter AG, Budapest/Hungary) for critically reviewing the new section on 15N NMR. In spite of great efforts and many checks to eliminate errors, it is likely that some mistakes and inconsistencies remain. We would like to encourage our readers to contact us with comments and suggestions. Zürich and Minneapolis, August 2020

V



Contents

1 Introduction������������������������������������������ 1 1.1 Scope and Organization�������������������������������� 1 1.2 Abbreviations and Symbols������������������������������ 3 2 Summary Tables�������������������������������������� 5 2.1 General Tables�������������������������������������� 5 2.1.1 Calculation of the Number of Double Bond Equivalents from the Molecular Formula��������������������������� 5 2.1.2 Properties of Selected Nuclei����������������������� 6 2.1.3 Volume Susceptibilities and Corrections for External References in NMR Spectroscopy������������������� 7 2.1.4 References����������������������������������� 8 2.2 13C NMR Spectroscopy�������������������������������� 9 2.3 1H NMR Spectroscopy�������������������������������� 12 2.4 IR Spectroscopy������������������������������������ 15 2.5 Mass Spectrometry���������������������������������� 20 2.5.1 Average Masses of Naturally Occurring Elements with Masses and Representative Relative Abundances of Isotopes������ 20 2.5.2 Ranges of Natural Isotope Abundances of Selected Elements�� 27 2.5.3 Isotope Patterns of Naturally Occurring Elements�������� 28 2.5.4 Calculation of Isotope Distributions����������������� 29 2.5.5 Isotopic Abundances of Various Combinations of Chlorine, Bromine, Sulfur, and Silicon���������������������� 31 2.5.6 Isotope Patterns of Combinations of Cl and Br���������� 33 2.5.7 Indicators of the Presence of Heteroatoms������������� 34 2.5.8 Rules for Determining the Relative Molecular Weight (Mr)�� 36 2.5.9 Homologous Mass Series as Indications of Structural Type�� 37 2.5.10 Mass Correlation Table������������������������� 39 2.5.11 Common Fragmentations of [M+H]+ in ESI- and API-MS/MS-Spectra �������������������������� 48 2.5.12 References��������������������������������� 51 2.6 UV/Vis Spectroscopy��������������������������������� 52

VII

VIII

Table of Contents

3 Combination Tables���������������������������������� 3.1 Alkanes, Cycloalkanes�������������������������������� 3.2 Alkenes, Cycloalkenes�������������������������������� 3.3 Alkynes������������������������������������������ 3.4 Aromatic Hydrocarbons������������������������������� 3.5 Heteroaromatic Compounds���������������������������� 3.6 Halogen Compounds��������������������������������� 3.7 Oxygen Compounds���������������������������������� 3.7.1 Alcohols and Phenols��������������������������� 3.7.2 Ethers������������������������������������� 3.8 Nitrogen Compounds��������������������������������� 3.8.1 Amines������������������������������������ 3.8.2 Nitro Compounds����������������������������� 3.9 Thiols and Sulfides���������������������������������� 3.10 Carbonyl Compounds�������������������������������� 3.10.1 Aldehydes���������������������������������� 3.10.2 Ketones����������������������������������� 3.10.3 Carboxylic Acids����������������������������� 3.10.4 Esters and Lactones��������������������������� 3.10.5 Amides and Lactams��������������������������� 4

13C

NMR Spectroscopy�������������������������������� 4.1 Alkanes������������������������������������������ 4.1.1 Chemical Shifts������������������������������� 4.1.2 Coupling Constants���������������������������� 4.1.3 References���������������������������������� 4.2 Alkenes������������������������������������������ 4.2.1 Chemical Shifts ������������������������������ 4.2.2 Coupling Constants���������������������������� 4.2.3 References���������������������������������� 4.3 Alkynes������������������������������������������ 4.3.1 Chemical Shifts������������������������������� 4.3.2 Coupling Constants���������������������������� 4.3.3 References���������������������������������� 4.4 Alicyclics����������������������������������������� 4.4.1 Chemical Shifts ������������������������������ 4.4.2 Coupling Constants���������������������������� 4.5 Aromatic Hydrocarbons������������������������������� 4.5.1 Chemical Shifts������������������������������� 4.5.2 Coupling Constants���������������������������� 4.5.3 References����������������������������������

55 55 56 57 58 59 60 62 62 63 65 65 66 67 68 68 69 70 71 73 75

75 75 84 85 86 86 90 90 91 91 92 92 93 93 98 99 99 106 106



Table of Contents 4.6 Heteroaromatic Compounds���������������������������� 4.6.1 Chemical Shifts������������������������������� 4.6.2 Coupling Constants���������������������������� 4.7 Halogen Compounds��������������������������������� 4.7.1 Fluoro Compounds���������������������������� 4.7.2 Chloro Compounds���������������������������� 4.7.3 Bromo Compounds���������������������������� 4.7.4 Iodo Compounds������������������������������ 4.7.5 References���������������������������������� 4.8 Alcohols, Ethers, and Related Compounds������������������� 4.8.1 Alcohols����������������������������������� 4.8.2 Ethers������������������������������������� 4.9 Nitrogen Compounds��������������������������������� 4.9.1 Amines������������������������������������ 4.9.2 Nitro and Nitroso Compounds��������������������� 4.9.3 Nitrites and Nitrates���������������������������� 4.9.4 Nitrosamines and Nitramines���������������������� 4.9.5 Azo and Azoxy Compounds����������������������� 4.9.6 Imines and Oximes���������������������������� 4.9.7 Hydrazines, Hydrazones, and Carbodiimides������������ 4.9.8 Nitriles and Isonitriles��������������������������� 4.9.9 Isocyanates, Thiocyanates, and Isothiocyanates���������� 4.10 Sulfur Compounds���������������������������������� 4.10.1 Thiols������������������������������������ 4.10.2 Sulfides����������������������������������� 4.10.3 Disulfides and Sulfonium Salts�������������������� 4.10.4 Sulfoxides and Sulfones������������������������ 4.10.5 Sulfonic and Sulfinic Acids and Derivatives����������� 4.10.6 Sulfurous and Sulfuric Acid Derivatives�������������� 4.10.7 Sulfur-Containing Carbonyl Derivatives�������������� 4.11 Carbonyl Compounds�������������������������������� 4.11.1 Aldehydes���������������������������������� 4.11.2 Ketones����������������������������������� 4.11.3 Carboxylic Acids����������������������������� 4.11.4 Esters and Lactones��������������������������� 4.11.5 Amides and Lactams��������������������������� 4.11.6 Miscellaneous Carbonyl Derivatives���������������� 4.12 Miscellaneous Compounds���������������������������� 4.12.1 Compounds with Group IV Elements���������������� 4.12.2 Phosphorus Compounds������������������������ 4.12.3 Miscellaneous Organometallic Compounds������������

IX 107 107 114 115 115 117 118 119 119 120 120 121 123 123 125 126 126 126 127 128 128 129 130 130 130 131 132 133 133 134 135 135 136 138 140 142 144 146 146 147 149

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X

5

4.13 Natural Products����������������������������������� 4.13.1 Amino Acids�������������������������������� 4.13.2 Carbohydrates������������������������������� 4.13.3 Nucleotides and Nucleosides��������������������� ­4.13.4 Steroids����������������������������������� 4.14 Spectra of Solvents and Reference Compounds��������������� 4.14.1 13C NMR Spectra of Common Deuterated Solvents������ 4.14.2 13C NMR Spectra of Secondary Reference Compounds ��� 4.14.3 13C NMR Spectrum of a Mixture of Common Nondeuterated Solvents������������������������

151 151 155 157 159 160

1H

167

5.1 5.2

5.3 5.4 5.5 5.6 5.7

5.8 5.9

NMR Spectroscopy��������������������������������� Alkanes������������������������������������������ 5.1.1 Chemical Shifts������������������������������� 5.1.2 Coupling Constants���������������������������� Alkenes������������������������������������������ 5.2.1 Ethylenes����������������������������������� 5.2.2 Conjugated Dienes����������������������������� 5.2.3 Allenes������������������������������������ Alkynes������������������������������������������ Alicyclics����������������������������������������� Aromatic Hydrocarbons������������������������������� Heteroaromatic Compounds���������������������������� 5.6.1 Non-Condensed Heteroaromatic Rings��������������� 5.6.2 Condensed Heteroaromatic Rings������������������� Halogen Compounds��������������������������������� 5.7.1 Fluoro Compounds���������������������������� 5.7.2 Chloro Compounds���������������������������� 5.7.3 Bromo Compounds���������������������������� 5.7.4 Iodo Compounds������������������������������ 5.7.5 References���������������������������������� Alcohols, Ethers, and Related Compounds������������������� 5.8.1 Alcohols����������������������������������� 5.8.2 Ethers������������������������������������� Nitrogen Compounds��������������������������������� 5.9.1 Amines������������������������������������ 5.9.2 Nitro and Nitroso Compounds��������������������� 5.9.3 Nitrites and Nitrates���������������������������� 5.9.4 Nitrosamines, Azo and Azoxy Compounds������������� 5.9.5 Imines, Oximes, Hydrazines, Hydrazones, and Azines����� 5.9.6 Nitriles and Isonitriles���������������������������

160 164 165 167 167 172 174 174 180 181 182 183 187 194 194 201 206 206 208 209 210 210 211 211 213 216 216 218 219 219 220 221



Table of Contents

XI

5.9.7 Cyanates, Isocyanates, Thiocyanates, and Isothiocyanates��� 5.10 Sulfur Compounds���������������������������������� 5.10.1 Thiols������������������������������������ 5.10.2 Sulfides����������������������������������� 5.10.3 Disulfides and Sulfonium Salts������������������� 5.10.4 Sulfoxides and Sulfones������������������������ 5.10.5 Sulfonic, Sulfurous, and Sulfuric Acids and Derivatives��� 5.10.6 Thiocarboxylate Derivatives��������������������� 5.11 Carbonyl Compounds�������������������������������� 5.11.1 Aldehydes���������������������������������� 5.11.2 Ketones����������������������������������� 5.11.3 Carboxylic Acids and Carboxylates����������������� 5.11.4 Esters and Lactones��������������������������� 5.11.5 Amides and Lactams��������������������������� 5.11.6 Miscellaneous Carbonyl Derivatives���������������� 5.12 Miscellaneous Compounds���������������������������� 5.12.1 Compounds with Group IV Elements���������������� 5.12.2 Phosphorus Compounds������������������������ 5.12.3 Miscellaneous Compounds���������������������� 5.12.4 References��������������������������������� 5.13 Natural Products����������������������������������� 5.13.1 Amino Acids�������������������������������� 5.13.2 Carbohydrates������������������������������� 5.13.3 Nucleotides and Nucleosides��������������������� 5.14 Spectra of Solvents and Reference Compounds��������������� 5.14.1 1H NMR Spectra of Common Deuterated Solvents������� 5.14.2 1H NMR Spectra of Secondary Reference Compounds���� 5.14.3 1H NMR Spectrum of a Mixture of Common Nondeuterated Solvents������������������������

222 223 223 224 225 225 226 226 227 227 228 229 230 231 235 237 237 238 241 242 243 243 247 249 251 251 253

6 Heteronuclear NMR Spectroscopy����������������������� 6.1 15N NMR Spectroscopy������������������������������� 6.1.1 Heteroaromatic Compounds����������������������� 6.1.2 Amines and Ammonium Salts��������������������� 6.1.3 Carbonyl and Thiocarbonyl Derivatives��������������� 6.1.4 Further Amine Derivatives������������������������ 6.1.5 Compounds with C=N Bonds���������������������� 6.1.6 Compounds with N=O Bonds���������������������� 6.1.7 Compounds with Nitrogen-Nitrogen Multiple Bonds������ 6.1.8 Nitriles, Isonitriles, Cyanates, Isocyanates and Thio Derivatives��������������������������������

255

254 255 255 259 261 263 265 267 268 269

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6.1.9 Natural Products������������������������������ 6.1.10 Reference Compounds������������������������� 6.1.11 References��������������������������������� 6.2 19F NMR Spectroscopy������������������������������� 6.2.1 19F Chemical Shifts of Perfluoroalkanes��������������� 6.2.2 Estimation of 19F Chemical Shifts of Substituted Fluoroethylenes������������������������������ 6.2.3 Coupling Constants in Fluorinated Alkanes and Alkenes���� 6.2.4 19F Chemical Shifts of Allenes and Alkynes������������ 6.2.5 19F Chemical Shifts and Coupling Constants of Fluorinated Alicyclics���������������������������������� 6.2.6 19F Chemical Shifts and Coupling Constants of Aromatics and Heteroaromatics��������������������������� 6.2.7 19F Chemical Shifts of Alcohols and Ethers������������ 6.2.8 19F Chemical Shifts of Fluorinated Amine, Imine, and Hydroxyl­amine Derivatives����������������������� 19 6.2.9 F Chemical Shifts of Sulfur Compounds������������� 6.2.10 19F Chemical Shifts of Carbonyl and Thiocarbonyl Compounds��������������������������������� 6.2.11 19F Chemical Shifts of Fluorinated Boron, Phosphorus, . and Silicon Compounds������������������������ 6.2.12 19F Chemical Shifts of Natural Product Analogues������� 6.2.13 References��������������������������������� 29 6.3 Si NMR Spectroscopy������������������������������� 6.3.1 Silicon-Carbon Compounds����������������������� 6.3.2 Silicon-Halogen Compounds���������������������� 6.3.3 Silicon-Oxygen, Nitrogen, and Sulfur Compounds�������� 6.3.4 Organic Di- and Oligosilicon Compounds������������� 6.3.5 Silicon-Organic Phosphorus Compounds�������������� 6.3.6 References���������������������������������� 6.4 31P NMR Spectroscopy������������������������������� 6.4.1 31P Chemical Shifts of Tricoordinated Phosphorus, PR1R2R3� 6.4.2 31P Chemical Shifts of Tetracoordinated Phosphonium Compounds��������������������������������� 6.4.3 31P Chemical Shifts of Compounds with a P=C or P=N Bond� 6.4.4 31P Chemical Shifts of Tetracoordinated P(=O) and P(=S) Compounds��������������������������������� 31 6.4.5 P Chemical Shifts of Penta- and Hexacoordinated Phosphorus Compounds������������������������� 6.4.6 31P Chemical Shifts of Natural Phosphorus Compounds����

270 274 275 277 277 281 282 283 284 285 288 289 290 291 292 293 294 295 295 296 297 297 298 298 299 299 300 301 302 304 305



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XIII

7 IR Spectroscopy������������������������������������� 7.1 Alkanes������������������������������������������ 7.2 Alkenes������������������������������������������ 7.2.1 Monoenes ���������������������������������� 7.2.2 Allenes������������������������������������ 7.3 Alkynes������������������������������������������ 7.4 Alicyclics����������������������������������������� 7.5 Aromatic Hydrocarbons������������������������������� 7.6 Heteroaromatic Compounds���������������������������� 7.7 Halogen Compounds��������������������������������� 7.7.1 Fluoro Compounds���������������������������� 7.7.2 Chloro Compounds���������������������������� 7.7.3 Bromo Compounds���������������������������� 7.7.4 Iodo Compounds������������������������������ 7.8 Alcohols, Ethers, and Related Compounds������������������� 7.8.1 Alcohols and Phenols��������������������������� 7.8.2 Ethers, Acetals, and Ketals������������������������ 7.8.3 Epoxides����������������������������������� 7.8.4 Peroxides and Hydroperoxides��������������������� 7.9 Nitrogen Compounds��������������������������������� 7.9.1 Amines and Related Compounds�������������������� 7.9.2 Nitro and Nitroso Compounds��������������������� 7.9.3 Imines and Oximes���������������������������� 7.9.4 Azo, Azoxy, and Azothio Compounds���������������� 7.9.5 Nitriles and Isonitriles��������������������������� 7.9.6 Diazo Compounds����������������������������� 7.9.7 Cyanates and Isocyanates������������������������ 7.9.8 Thiocyanates and Isothiocyanates������������������� 7.10 Sulfur Compounds���������������������������������� 7.10.1 Thiols and Sulfides���������������������������� 7.10.2 Sulfoxides and Sulfones������������������������ 7.10.3 Thiocarbonyl Derivatives������������������������ 7.10.4 Thiocarbonic Acid Derivatives�������������������� 7.11 Carbonyl Compounds�������������������������������� 7.11.1 Aldehydes���������������������������������� 7.11.2 Ketones����������������������������������� 7.11.3 Carboxylic Acids����������������������������� 7.11.4 Esters and Lactones��������������������������� 7.11.5 Amides and Lactams��������������������������� 7.11.6 Acid Anhydrides����������������������������� 7.11.7 Acid Halides��������������������������������

307 307 310 310 313 314 315 317 320 322 322 323 324 324 325 325 326 328 329 330 330 332 334 336 337 338 339 340 342 342 343 345 345 348 348 349 352 354 357 360 361

XIV

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7.11.8 Carbonic Acid Derivatives����������������������� 7.12 Miscellaneous Compounds���������������������������� 7.12.1 Silicon Compounds��������������������������� 7.12.2 Phosphorus Compounds������������������������ 7.12.3 Boron Compounds���������������������������� 7.13 Amino Acids�������������������������������������� 7.14 Solvents, Suspension Media, and Interferences��������������� 7.14.1 Infrared Spectra of Common Solvents��������������� 7.14.2 Infrared Spectra of Suspension Media��������������� 7.14.3 Interferences in Infrared Spectra�������������������

362 365 365 366 369 370 371 371 372 373

8 Mass Spectrometry����������������������������������� 375 8.1 Alkanes������������������������������������������ 375 8.2 Alkenes������������������������������������������ 377 8.3 Alkynes������������������������������������������ 379 8.4 Alicyclics����������������������������������������� 380 8.5 Aromatic Hydrocarbons������������������������������� 383 8.6 Heteroaromatic Compounds���������������������������� 385 8.7 Halogen Compounds��������������������������������� 390 8.8 Alcohols, Ethers, and Related Compounds������������������� 8.8.1 Alcohols and Phenols��������������������������� 8.8.2 Hydroperoxides������������������������������ 8.8.3 Ethers������������������������������������� 8.8.4 Aliphatic Epoxides����������������������������

392 392 394 395 398

8.9 Nitrogen Compounds �������������������������������� 8.9.1 Amines������������������������������������ 8.9.2 Nitro Compounds����������������������������� 8.9.3 Diazo Compounds and Azobenzenes����������������� 8.9.4 Azides������������������������������������� 8.9.5 Nitriles and Isonitriles�������������������������� 8.9.6 Cyanates, Isocyanates, Thiocyanates, and Isothiocyanates��� 8.9.7 References����������������������������������

401 401 404 405 405 406 407 410

8.8.5 Aliphatic Peroxides���������������������������� 399 8.8.6 References���������������������������������� 400

8.10 Sulfur Compounds���������������������������������� 8.10.1 Thiols������������������������������������ 8.10.2 Sulfides and Disulfides������������������������� 8.10.3 Sulfoxides and Sulfones������������������������ 8.10.4 Sulfonic Acids and Their Esters and Amides����������� 8.10.5 Thiocarboxylic Acid Esters����������������������

411 411 412 414 417 418



Table of Contents

XV

8.10.6 References��������������������������������� 419

8.11 Carbonyl Compounds�������������������������������� 8.11.1 Aldehydes��������������������������������� 8.11.2 Ketones����������������������������������� 8.11.3 Carboxylic Acids����������������������������� 8.11.4 Carboxylic Acid Anhydrides��������������������� 8.11.5 Esters and Lactones��������������������������� 8.11.6 Amides and Lactams�������������������������� 8.11.7 Imides������������������������������������ 8.11.8 References��������������������������������� 8.12 Miscellaneous Compounds����������������������������

8.12.1 Trialkylsilyl Ethers��������������������������� 8.12.2 Phosphorus Compounds������������������������ 8.12.3 References��������������������������������� 8.13 Mass Spectra of Common Solvents and Matrix Compounds������� 8.13.1 Electron Impact Ionization Mass Spectra of Common Solvents����������������������������������� 8.13.2 Spectra of Common FAB MS Matrix and Calibration Compounds��������������������������������� 8.13.3 Spectra of Common MALDI MS Matrix Compounds����� 8.13.4 References��������������������������������� 9 UV/Vis Spectroscopy���������������������������������� 9.1 Correlation between Wavelength of Absorbed Radiation and Observed Color����������������������������������� 9.2 Simple Chromophores�������������������������������� 9.3 Conjugated Alkenes���������������������������������� 9.3.1 Dienes and Polyenes���������������������������� 9.3.2 α,β-Unsaturated Carbonyl Compounds��������������� 9.4 Aromatic Hydrocarbons������������������������������� 9.4.1 Monosubstituted Benzenes����������������������� 9.4.2 Polysubstituted Benzenes������������������������ 9.4.3 Aromatic Carbonyl Compounds�������������������� 9.5 Reference Spectra����������������������������������� 9.5.1 Alkenes and Alkynes��������������������������� 9.5.2 Aromatic Compounds��������������������������� 9.5.3 Heteroaromatic Compounds����������������������� 9.5.4 Miscellaneous Compounds����������������������� 9.5.5 Nucleotides��������������������������������� 9.6 Common Solvents�����������������������������������

420 420 421 423 424 424 426 429 430 431 431 431 432 433 433 436 441 443 445 445 445 447 447 448 450 450 451 452 453 453 454 459 461 463 464

Subject Index������������������������������������������ 465

1 Introduction

1.1 Scope and Organization The present data collection is intended to serve as an aid in the interpretation of molecular spectra for the elucidation and confirmation of the structure of organic compounds. It consists of reference data, spectra, and empirical correlations from mass spectrometry and 1H, 13C, 15N, 19F, 29Si, and 31P nuclear magnetic resonance (NMR), infrared (IR), Raman, and ultraviolet–visible (UV/vis) spectroscopy. It is to be viewed as a supplement to textbooks and specific reference works dealing with these spectroscopic techniques. The use of this book to interpret spectra only requires the knowledge of basic principles of the techniques, but its content is structured in a way that it will serve as a reference book also to specialists. Chapters 2 and 3 contain Summary Tables and Combined Tables of the most relevant spectral characteristics of structural elements. While Chapter 2 is organized according to the different spectroscopic techniques, Chapter 3 provides for each class of structural elements spectroscopic information obtained with various techniques. These two chapters should assist users that are less familiar with spectra interpretation to identify the classes of structural elements present in samples of their interest. The four chapters with data from 13C NMR, 1H NMR and IR spectroscopy as well as mass spectrometry are ordered in the same manner by compound types. These cover the various skeletons (alkyl, alkenyl, alkynyl, alicyclic, aromatic, and heteroaromatic), the most important substituents (halogen, single-bonded oxygen, nitrogen, sulfur, and carbonyl), and some specific compound classes (miscellaneous compounds and natural products). Finally, a spectra collection of common solvents, auxiliary compounds (such as matrix materials and references) and commonly found impurities is provided for each method. Not only the strictly analogous order of the data but also the optical marks on the edge of the pages help fast crossreferencing between the various spectroscopic techniques. Because their data sets are less comprehensive, the chapters on 15N, 19F, 29Si, and 31P NMR and UV/vis are not organized exactly in the same manner. Although currently UV/vis spectroscopy is only marginally relevant to structure elucidation, its importance might increase by the advent of high throughput analyses. Also, the reference data presented in the UV/vis chapter are useful in connection with optical sensors and the widely applied UV/vis detectors in chromatography and electrophoresis. Since a large part of the tabulated data either comes from our own measurements or is based on a large body of literature data, comprehensive references to published sources are not included. Whenever possible, the data refer to conventional modes and conditions of measurement. For example, unless the solvent is indicated, the NMR chemical shifts were determined usually with deuterochloroform as solvent. Likewise, the IR spectra were measured using solvents of low polarity, such as © The Author(s), under exclusive license to Springer-Verlag GmbH, DE, part of Springer Nature 2020 E. Pretsch et al., Structure Determination of Organic Compounds, https://doi.org/10.1007/978-3-662-62439-5_1

1

2

1 Introduction



chloroform or carbon disulfide. Mass spectral data were recorded with electron impact ionization at 70 eV. While retaining the basic structure of the previous editions, numerous reference entries have been updated and new entries have been added. Altogether, more than 10% of the data is new. The chapter on 15N and 29Si NMR is entirely new and the section on mass spectrometry now contains fragmentation rules for MS/MS analysis after soft ionization.



1.2 Abbreviations and Symbols

1.2 Abbreviations and Symbols al aliphatic Ac acetyl alk alkyl alken alkenyl API atmospheric preassure ionization ar aromatic as asymmetric ax axial comb combination frequency d doublet δ IR: deformation vibration NMR: chemical shift DFTMP 1,2-difluoro(trimethylsilyl)methylphosphonic acid DMSO dimethyl sulfoxide DSS 3-(trimethylsilyl)-1-propanesulfonic acid sodium salt (sodium 4,4-di­methyl-4-silapentane-1-sulfonate) eq equatorial ESI electrospray ionization EtOH ethanol ε molar absorptivity Frag fragment γ skeletal vibration gem geminal hal halogen ip in plane vibration J coupling constant M+. molecular radical ion M r relative molecular mass MeOH methanol m/z mass to charge ratio ν frequency ~ν wavenumber oop out of plane vibration ref reference satd. saturated sh shoulder st stretching vibration sy symmetric TFA trifluoroacetic acid THF tetrahydrofuran TMS tetramethylsilane vic vicinal

3

2 Summary Tables

2.1 General Tables 2.1.1 Calculation of the Number of Double Bond Equivalents from the Molecular Formula General Equation

double bond equivalents = 1 + ½ ∑ni (vi - 2) i

ni: number of atoms of element i in molecular formula vi: formal valence of element i Short Cut For compounds containing only C, H, O, N, S, and halogens, the following steps permit a quick and simple calculation of the number of double bond equivalents: 1. O and divalent S are deleted from the molecular formula 2. Halogens are replaced by H 3. Trivalent N is replaced by CH 4. The resulting hydrocarbon, CnHx, is compared with the saturated hydrocarbon, CnH2n+2. Each double bond equivalent reduces the number of H atoms by 2:

double bond equivalents = ½ (2 n + 2 - x)

The above formula does not take into account additional double bond equivalents that result from the higher valences of N that is not trivalent or S that is not divalent. Ignoring higher valences, this formula predicts for example, for nitromethane one double bond equivalent and for dimethyl sulfoxide and dimethyl sulfone none.

© The Author(s), under exclusive license to Springer-Verlag GmbH, DE, part of Springer Nature 2020 E. Pretsch et al., Structure Determination of Organic Compounds, https://doi.org/10.1007/978-3-662-62439-5_2

5

6

2 Summary Tables

2.1.2 Properties of Selected Nuclei [1]

1H

2H 3H

6Li 7Li

10B 11B

13C

14N 15N 17O 19F

23Na 27Al 29Si 31P 33S

35Cl 37Cl

63Cu 65Cu 77Se 79Br 81Br

107Ag 109Ag 111Cd

113Cd 117Sn 119Sn 195Pt

199Hg 207Pb

99.985 0.015 0.000 7.42 92.58 19.58 80.42 1.108 99.635 0.365 0.037 100.000 100.000 100.000 4.70 100.000 0.76 75.53 24.47 69.09 30.91 7.58 50.54 49.46 51.82 48.18 12.75 12.26 7.61 8.58 33.8 16.84 22.6

1/2 1 1/2 1 3/2 3 3/2 1/2 1 1/2 5/2 1/2 3/2 5/2 1/2 1/2 3/2 3/2 3/2 3/2 3/2 1/2 3/2 3/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2 1/2

100.0 15.4 106.7 14.7 38.9 10.7 32.1 25.1 7.3 10.1 13.6 94.1 26.5 26.1 19.9 40.5 7.6 9.8 8.2 26.5 28.4 19.1 25.1 27.1 4.0 4.6 21.2 22.2 35.6 37.3 21.5 17.8 20.9

1 9.6 × 10-3 1.2 8.5 × 10-3 2.9 × 10-1 2.0 × 10-2 1.6 × 10-1 1.6 × 10-2 1.0 × 10-3 1.0 × 10-3 2.9 × 10-2 8.3 × 10-1 9.3 × 10-2 2.1 × 10-1 7.9 × 10-3 6.6 × 10-2 2.3 × 10-3 4.8 × 10-3 2.7 × 10-3 9.4 × 10-2 1.2 × 10-1 7.0 × 10-3 7.9 × 10-2 9.9 × 10-2 6.8 × 10-5 1.0 × 10-4 9.4 × 10-3 1.1 × 10-2 4.5 × 10-2 5.2 × 10-2 9.9 × 10-3 5.7 × 10-3 9.2 × 10-3

Relative sensitivity at natural abundance 1 1.5 × 10-6 0 6.3 × 10-4 2.7 × 10-1 3.9 × 10-3 1.3 × 10-1 1.8 × 10-4 1.0 × 10-3 3.8 × 10-6 1.1 × 10-5 8.3 × 10-1 9.3 × 10-2 2.1 × 10-1 3.7 × 10-4 6.6 × 10-2 1.7 × 10-5 3.6 × 10-3 6.7 × 10-4 6.5 × 10-2 3.6 × 10-2 5.3 × 10-4 4.0 × 10-2 4.9 × 10-2 3.5 × 10-5 4.9 × 10-5 1.2 × 10-3 1.4 × 10-3 3.4 × 10-3 4.4 × 10-3 3.4 × 10-3 9.5 × 10-4 2.1 × 10-4

Electric quadrupole moment [e × 10-24 cm2] 2.8 × 10-3 -8 × 10-4 -4 × 10-2 7.4 × 10-2 3.6 × 10-2 1.9 × 10-2 -2.6 × 10-2 1.0 × 10-1 1.5 × 10-1

Isotope Natural Spin Frequency Relative abundance quantum [MHz] at sensitivity [%] number, I 2.35 Tesla of nucleus

-6.4 × 10-2 -1.0 × 10-1 -7.9 × 10-2 -2.1 × 10-1 -2.0 × 10-1 3.7 × 10-1 3.1 × 10-1

2.1 General Tables



7

2.1.3 Volume Susceptibilities and Corrections for External References in NMR Spectroscopy [2, 3] Compound acetic acid acetone acetonitrile ammonium chloride (satd. in H2O) ammonium nitrate (satd. in H2O) benzene bromobenzene bromoform carbon disulfide carbon tetrachloride chlorobenzene chloroform cyclohexane dibromomethane diethyl ether diisopropyl amine dimethyl sulfoxide 1,4-dioxane ethanol

Volume susceptibility × 106 -0.553 -0.457 -0.532 -0.769 -0.722 -0.615 -0.744 -0.941 -0.693 -0.684 -0.684 -0.735 -0.608 -0.935 -0.531 -0.598 -0.618 -0.612 -0.576

Compound ethyl acetate n-hexane methanol methylene chloride nitric acid (1 M in H2O) nitric acid (70% w/w in H2O) nitrobenzene nitromethane pyridine sodium nitrite (satd. in H2O) sulfuric acid (100%) toluene 1,1,2,2-tetrachloroethane tetramethylsilane trifluoroacetic acid water, H2O water, D2O

Volume susceptibility × 106 -0.553 -0.568 -0.529 -0.728 -0.715 -0618 -0.604 -0.391 -0.605 -0.729 -0.723 -0.619 -0.853 -0.543 -0.583 -0.716 -0.705

The local magnetic field depends on the volume susceptibility χ of the medium. The observed chemical shifts δobs must be corrected for the difference between the magnetic susceptibilities of the reference and probe if the reference is inserted in a cylindrical capillary into the sample tube (external reference). For superconducting magnets, in which the magnetic field is parallel to the sample tube, the corrected value δcorr is: δ corr = δ obs +

(

)

(

4π − χ sample = δ obs + 4.19 χ reference − χ sample χ 3 reference

)

In instruments with permanent magnets and electromagnets, the magnetic field is perpendicular to the sample tube. Here the following equation applies: δ corr = δ obs −

(

)

(

2π − χ sample = δ obs − 2.09 χ reference − χ sample χ 3 reference

)

Example: If the sample is a D2O solution and TMS sealed in a capillary is used as external reference, δcorr = δobs + 0.62 for superconducting magnets and δcorr = δobs - 0.31 for instruments with permanent magnets or electromagnets.

8

2 Summary Tables

2.1.4 References



[1] J.H. Nelson, Nuclear Magnetic Resonance Spectroscopy, Prentice Hall, Upper Saddle River, 2003. [2] Physical Constants of Organic Compounds, In CRC Handbook of Chemistry and Physics, 100th Edition (Internet Version 2019), John R. Rumble (Ed.). CRC Press/Taylor & Francis, Boca Raton, FL. [3] M. Witanowski, L. Stefaniak, G.A. Webb, Nitrogen NMR Spectroscopy, In Annu. Rep. NMR Spectrosc. Vol. 25, E.F. Mooney (Ed.). Academic Press, New York, 1993.

2.2 13C NMR Spectroscopy

2.2

13C

9

NMR Spectroscopy

Summary of the Regions of Chemical Shifts, δ (in ppm), for C Atoms in Various Chemical Environments (C atoms are specified as follows: Q for CH3, T for CH2, D for CH, and S for C) 240 220 200 180 160 140 120 100 80 60 H3C C

40 20

H3C C X H3C C X

Q

H3C S

Q

C CH2 C

T

C CH2 S

T

C CH C C

D Q

H3C COX; X: C, O, N C C

D,S

CH3Cl

Q

C CH S C

D

H3C N

Q

C C C C C

S

C CH2COX; X: C, O, N

T

C CHCOX; X: C, O, N C

D

C CH2 N

T

C S C C C

S T

C CH2Cl C CH N C C COX; X: C,O,N C C C

D S

H3C O C N C C C C CH Cl C H3C NO2

0 ppm

Q S D Q 240 220 200 180 160 140 120 100 80 60

40 20

0 ppm

2 Summary Tables

10

240 220 200 180 160 140 120 100 80 60 C CH2 O

S D S T D

C C

D, S

O O

T, D, S S

C X; X: any substituent C X C X: any substituent C

D, S

C N X

C N

D

S

C H; X: any substituent

C N C

0 ppm

T

C Cl C C C C CH NO2 C C O C C C C NO2 C C C H C C H

N

40 20

D

C CH2 NO2

C

0 ppm

T

C CH O C

X

40 20

S D, S

X: any substituent

C

C N

O

D, S S S S

C COX; X: O, N, Cl C COOH

S S

C CSX; X: O, N

S S D

C CHO C C O C C C S C

S S 240 220 200 180 160 140 120 100 80 60

2.2 13C NMR Spectroscopy 13C

Chemical Shifts of Carbonyl Groups (δ in ppm)

R –H –CH3 –CH2CH3 –CH(CH3)2 –C(CH3)3 –n-C8H17 –CH2Cl –CHCl2 –CCl3 –cyclohexyl –CH=CH2 –C ––– CH –phenyl

R–CHO 197.0 200.5 202.7 204.6 205.6 202.8 194.0 184.3 176.9 204.7 194.4 176.8 192.0

R–COCH3 200.5 206.7 207.6 211.8 213.5 208.9 200.1 193.6 186.3 209.4 197.5 183.6 196.9

R–COOH 166.3 178.1 181.5 184.1 185.9 180.7 173.7 170.4 167.1 182.1 172.0 156.5 172.6

R–COO– 171.3 182.6 185.1 181.8 188.6 184.7 175.9 171.8 167.6 185.4 174.5

R –H –CH3 –CH2CH3 –CH(CH3)2 –C(CH3)3 –n-C8H17 –CH2Cl –CHCl2 –CCl3 –cyclohexyl –CH=CH2 –C ––– CH –phenyl

R–COOCH3 161.6 171.3 173.3 177.4 178.8 174.2 167.8 165.1 162.5 175.3 166.5 153.4 166.8

R–CONH2 167.6 173.4 177.2 180.2 180.9 176.3 168.3 166.6 162.8 177.3 168.3 154.9 169.7

R–COOCO-R 158.5 166.6 170.9 172.8 173.9 169.4 162.1 157.6 154.0

R–COCl

162.4

177.6

170.4 174.7 178.0 180.3 173.7 167.7 165.5 163.3 176.3 165.6 168.0

11

12

2.3

2 Summary Tables 1H

NMR Spectroscopy

Summary of the Regions of Chemical Shifts, δ (in ppm), for H Atoms in Various Chemical Environments 14 13 12 11 10 9

8

7

6

5

4

3

2

1

0 ppm

14 13 12 11 10 9

8

7

6

5

4

3

2

1

0 ppm

2.3 1H NMR Spectroscopy

13

14 13 12 11 10 9

8

7

6

5

4

3

2

1

0 ppm

14 13 12 11 10 9

8

7

6

5

4

3

2

1

0 ppm

2 Summary Tables

14

14 13 12 11 10 9

8

7

6

5

4

3

2

1

0 ppm

14 13 12 11 10 9

8

7

6

5

4

3

2

1

0 ppm

CH2 Cl

O S O H2C O H2C

OH

H2C

Cl S

O CH O O

Cl CH2 N

CH2 O

O C CH O C C O CH2 N N CO H O CH2Cl H; heteroaromatic CH O

H

N

O

H

O

heteroaromatic NH O O

H

C N

OH

CHO COOH



2.4 IR Spectroscopy

15

2.4 IR Spectroscopy Summary of the Most Important IR Absorption Bands (~ν in cm-1) 3500

3000

2500

2000

1500

1000

500 cm -1

3500

3000

2500

2000

1500

1000

500 cm -1

δ

δ δ

16

2 Summary Tables

Summary of IR Absorption Bands of Carbonyl Groups (~ν in cm-1) 1900

1850

1800

1750

1700

1650

1600 1550 cm-1

1900

1850

1800

1750

1700

1650

1600 1550 cm-1



2.4 IR Spectroscopy

17

1900

1850

1800

1750

1700

1650

1600 1550 cm-1

1900

1850

1800

1750

1700

1650

1600 1550 cm-1

18

2 Summary Tables 1900

1850

1800

1750

1700

1650

1600 1550 cm-1

1900

1850

1800

1750

1700

1650

1600 1550 cm-1



2.4 IR Spectroscopy

19

1900

1850

1800

1750

1700

1650

1600 1550 cm-1

1900

1850

1800

1750

1700

1650

1600 1550 cm-1

(in solution)

(solid)

20

2 Summary Tables

2.5 Mass Spectrometry 2.5.1 Average Masses of Naturally Occurring Elements with Masses and Representative Relative Abundances of Isotopes [1–3] Element Isotope H

1H

Mass

1.00794a,b

2H

1.007825 2.014102

He

4.002602a

3He 4He

Li

6Li 7Li

Be

9Be

B

10B 11B

C

12C 13C

N

14N 15N

O

16O 17O 18O

3.016029 4.002603 6.941a 6.015123 7.016005 9.012182 9.012182

10.811a 10.012937 11.009305

Abundance

(in water) 100c 0.0115 (in air) 0.000134 100

8.21d

100

100

24.8c 100

12.0107a 12.000000 13.003355

100 1.08

14.0067a 14.003074 15.000109

100 0.365

15.9994a 15.994915 16.999132 17.999161

100 0.038 0.205

Element Isotope

Mass

Abundance

F

18.998403 18.998403

Ne

20.1797a 19.992440 20.993847 21.991385

(in air) 100c 0.38 10.22

Na

22.989769 22.989769

100

Mg

24.3050 23.985042 24.985837 25.982593

100 12.66 13.94

Al

26.981538 26.981538

100

Si

28.0855a 27.976927 28.976495 29.973770

100 5.080 3.353

P

30.973762 30.973762

100

S

32.065a 31.972071 32.971459 33.967867 35.967081

100c 0.79 4.47 0.01

19F

20Ne 21Ne 22Ne

23Na

24Mg 25Mg 26Mg

27Al

28Si 29Si 30Si

31P

32S 33S 34S 36S

100



2.5 Mass Spectrometry Element Isotope Cl

Mass

35Cl 37Cl

35.453 34.968853 36.965903

Ar

39.948a

36Ar 38Ar 40Ar

K

39K 40K 41K

Ca

40Ca 42Ca 43Ca 44Ca 46Ca 48Ca

35.967545 37.962732 39.962383 39.0983 38.963707 39.963998 40.961826

100 0.0125 7.2167

40.078 39.962591 41.958618 42.958767 43.955482 45.953693 47.952534

100 0.667 0.139 2.152 0.004 0.193

44.955912 44.955912

Ti

47.867 45.952632 46.951763 47.947946 48.947870 49.944791

46Ti 47Ti 48Ti 49Ti 50Ti

V

50V 51V

100c 32.0 (in air) 0.3379 0.0635 100

Sc

45Sc

Abundance

50.9415 49.947159 50.943960

100

11.19 10.09 100 7.34 7.03

0.251 100

Element Isotope Cr

50Cr 52Cr 53Cr 54Cr

Mass

51.9961 49.946044 51.940508 52.940649 53.938880

Abundance 5.186 100 11.339 2.823

Mn

54.938045 54.938045

100

Fe

55.845 53.939611 55.934938 56.935394 57.933276

6.370 100 2.309 0.307

Co

58.933195 58.933195

100

Ni

58.6934 57.935343 59.930786 60.931056 61.928345 63.927966

100 38.5198 1.6744 5.3388 1.3596

63.546a 62.929598 64.927790

100 44.61

65.409 63.929142 65.926033 66.927127 67.924844 69.925319

100 57.96 8.49 39.41 1.31

55Mn

54Fe 56Fe 57Fe 58Fe

59Co

58Ni 60Ni 61Ni 62Ni 64Ni

Cu

63Cu 65Cu

Zn

64Zn 66Zn 67Zn 68Zn 70Zn

21

22

2 Summary Tables

Element Isotope Ga

69Ga 71Ga

Ge

70Ge 72Ge 73Ge 74Ge 76Ge

As

75As

Se

74Se 76Se 77Se 78Se 80Se 82Se

Br

79Br 81Br

Kr

78Kr 80Kr 82Kr 83Kr 84Kr 86Kr

Mass

69.723 68.925574 70.924701 72.64 69.924247 71.922076 72.923459 73.921178 75.921403 74.921597 74.921597

Abundance 100c 66.36

55.50 74.37 21.13 100 21.32

100

Element Isotope Rb

85Rb 87Rb

Sr

Mass

85.4678 84.911790 86.909181

Abundance 100 38.56

87.62a 83.913425 85.909260 86.908877 87.905612

0.68 11.94 8.48 100

Y

88.905848 88.905848

100

Zr

91.224 89.904704 90.905646 91.905041 93.906315 95.908273

100 21.81 33.33 33.78 5.44

Nb

92.906378 92.906378

100

95.94 91.906811 93.905088 94.905842 95.904680 96.906022 97.905408 99.907477

61.06 38.16 65.72 68.95 39.52 100 39.98

84Sr 86Sr 87Sr 88Sr

89Y

90Zr

78.96 73.922476 75.919214 76.919914 77.917309 79.916521 81.916699

1.79 18.89 15.38 47.91 100 17.60

79.904 78.918337 80.916291

100 97.28

Mo

83.798 77.920382 79.916379 81.913484 82.914136 83.911507 85.910611

(in air) 0.623c 4.011 20.343 20.180 100 30.321

95Mo

91Zr 92Zr 94Zr 96Zr

93Nb

92Mo 94Mo 96Mo 97Mo 98Mo 100Mo

Element Isotope Ru

96Ru 98Ru 99Ru

100Ru 101Ru 102Ru 104Ru

Rh

103Rh

Pd

102Pd 104Pd 105Pd 106Pd 108Pd 110Pd

Ag

107Ag 109Ag

Cd

106Cd 108Cd 110Cd 111Cd

112Cd 113Cd 114Cd 116Cd

2.5 Mass Spectrometry Mass

101.07 95.907598 97.905287 98.905939 99.904220 100.905582 101.904349 103.905433 102.905504 102.905504 106.42 101.905609 103.904036 104.905085 105.903486 107.903892 109.905153 107.8682 106.905097 108.904752 112.411 105.906459 107.904184 109.903002 110.904178 111.902758 112.904402 113.903359 115.904756

Abundance 17.56 5.93 40.44 39.94 54.07 100 59.02

100

3.73 40.76 81.71 100 96.82 42.88

100 92.90

4.35 3.10 43.47 44.55 83.99 42.53 100 26.07

Element Isotope In

113In 115In

Sn

112Sn 114Sn 115Sn 116Sn 117Sn 118Sn 119Sn

120Sn 122Sn 124Sn

Sb

121Sb 123Sb

Te

120Te 122Te 123Te 124Te 125Te 126Te 128Te 130Te

I

127I

Mass

114.818 112.904058 114.903878

23

Abundance 4.48 100

118.710 111.904818 113.902779 114.903342 115.901741 116.902952 117.901603 118.903309 119.902195 121.903439 123.905274

2.98 2.03 1.04 44.63 23.57 74.34 26.37 100 14.21 17.77

121.760 120.903816 122.904214

100 74.79

127.60 119.904020 121.903044 122.904270 123.902818 124.904431 125.903312 127.904463 129.906224

0.26 7.48 2.61 13.91 20.75 55.28 93.13 100

126.904473 126.904473

100

24

2 Summary Tables

Element Isotope Xe

124Xe 126Xe 128Xe 129Xe 130Xe 131Xe 132Xe 134Xe 136Xe

Cs

133Cs

Ba

130Ba 132Ba 134Ba 135Ba 136Ba 137Ba 138Ba

La

138La 139La

Ce

136Ce 138Ce 140Ce 142Ce

Pr

141Pr

Mass

131.293 123.905893 125.904274 127.903531 128.904779 129.903508 130.905082 131.904154 133.905395 135.907219 132.905452 132.905452 137.327 129.906321 131.905061 133.904508 134.905689 135.904576 136.905827 137.905247 138.90547 137.907112 138.906353

Abundance 0.354c 0.330 7.099 98.112 15.129 78.906 100 38.782 32.916

100

0.148 0.141 3.371 9.194 10.954 15.666 100

0.090 100

140.116 135.907172 137.905991 139.905439 141.909244

0.209 0.284 100 12.565

140.907653 140.907653

100

Element Isotope Nd

142Nd 143Nd 144Nd 145Nd 146Nd 148Nd 150Nd

Sm

144Sm 147Sm 148Sm 149Sm 150Sm 152Sm 154Sm

Eu

151Eu 153Eu

Gd

152Gd 154Gd 155Gd 156Gd 157Gd 158Gd 160Gd

Tb

159Tb

Mass

144.242 141.907723 142.909815 143.910087 144.912574 145.913117 147.916893 149.920891

Abundance 100 44.9 87.5 30.5 63.2 21.0 20.6

150.36 143.911999 146.914898 147.914823 148.917185 149.917276 151.919732 153.922209

11.48 56.04 42.02 51.66 27.59 100 85.05

151.964 150.919850 152.921230

91.61 100

157.25 151.919791 153.920866 154.922622 155.922123 156.923960 157.924104 159.927054

0.81 8.78 59.58 82.41 63.00 100 88.00

158.925347 158.925347

100



2.5 Mass Spectrometry Element Isotope Dy

156Dy 158Dy 160Dy 161Dy 162Dy 163Dy 164Dy

Mass

162.500 155.924283 157.924409 159.925198 160.926933 161.926798 162.928731 163.929175

Abundance 0.20 0.34 8.24 66.84 90.15 88.10 100

Ho

164.930322 164.930322

100

Er

167.259 161.928778 163.929200 165.930293 166.932048 167.932370 169.935464

0.41 4.78 100 68.26 80.52 44.50

165Ho

162Er 164Er 166Er 167Er 168Er 170Er

Tm

168.934213 168.934213

Yb

173.04 167.933897 169.934762 170.936326 171.936382 172.938211 173.938862 175.942572

0.41 9.55 44.86 68.58 50.68 100 40.09

174.967 174.940772 175.942686

100 2.66

169Tm

168Yb 170Yb 171Yb 172Yb 173Yb 174Yb 176Yb

Lu

175Lu 176Lu

100

Element Isotope Hf

174Hf 176Hf 177Hf 178Hf 179Hf 180Hf

Ta

180Ta 181Ta

W

180W 182W 183W 184W 186W

Re

185Re 187Re

Os

184Os 186Os 187Os 188Os 189Os 190Os 192Os

Ir

191Ir 193Ir

Mass

178.49 173.940046 175.941409 176.943221 177.943699 178.944816 179.946550

25

Abundance 0.46 14.99 53.02 77.77 38.83 100

180.94788 179.947465 180.947996

0.012 100

183.84 179.946704 181.948204 182.950223 183.950931 185.954364

0.39 86.49 46.70 100.0 92.79

186.207 184.952955 186.955753

59.74 100

190.23 183.952489 185.953838 186.955751 187.955838 188.958148 189.958447 191.961481

0.05 3.90 4.81 32.47 39.60 64.39 100

192.217 190.960594 192.962926

59.49 100.0

26

2 Summary Tables

Element Isotope Pt

190Pt 192Pt 194Pt 195Pt 196Pt 198Pt

Mass

195.084 189.959932 191.961038 193.962680 194.964791 195.964952 197.967893

Au

196.966569 196.966569

Hg

200.59 195.965833 197.966769 198.968280 199.968326 200.970302 201.970643 203.973494

197Au

196Hg 198Hg 199Hg 200Hg 201Hg 202Hg 204Hg

Abundance 0.041 2.311 97.443 100 74.610 21.172 100 0.50 33.39 56.50 77.36 44.14 100 23.01

Element Isotope Tl

203Tl 205Tl

Pb

Mass

204.3833 202.972344 204.974428

Abundance 41.88 100

207.2a 203.973044 205.974465 206.975897 207.976653

2.7 46.0 42.2 100

Bi

208.980399 208.980399

100

Th

232.038055 232.038055

100

U

238.02891 234.040952 235.043930 238.050788

0.0054e 0.7257 100

204Pb 206Pb 207Pb 208Pb

209Bi

232Th

234U 235U 238U

a Natural variations in the isotopic composition of terrestrial materials do not allow

to give a more precise value.

b The mole ratio of 2H in hydrogen from gas cylinders was reported to be as low as

0.000032.

c Commercially

available materials may have substantially different isotopic compositions if they were subjected to undisclosed or inadvertent isotopic fractionation. d Materials depleted in 6Li are commercial sources of laboratory shelf reagents and are known to have 6Li abundances in the range of 2.0007–7.672 atom percent, with natural materials at the higher end of this range. Average atomic masses vary between 6.939 and 6.996; if a more accurate value is required, it must be determined for the specific material. e Materials depleted in 235U are commercial sources of laboratory shelf reagents.



2.5 Mass Spectrometry

27

2.5.2 Ranges of Natural Isotope Abundances of Selected Elements [3] Element Isotope

Range [atom %]

H 1H 2H

99.9816–99.9974 0.0026–0.0184

He 3He 4He

4.6×10-8–0.0041 99.9959–100

Li 6Li 7Li B

10B 11B

C

12C 13C

N

14N 15N

O

16O 17O 18O

Ne 20Ne 21Ne 22Ne

7.225–7.714 92.275–92.786

18.929–20.386 79.614– 81.071 98.853–99.037 0.963–1.147 99.579–99.654 0.346–0.421 99.738–99.776 0.037–0.040 0.188–0.222 88.47–90.51 0.27–1.71 9.20– 9.96

Element Isotope Si 28Si 29Si 30Si S

32S

Range [atom %] 92.205–92.241 4.678–4.692 3.082–3.102

Element Isotope Sr 84Sr 86Sr 87Sr 88Sr

Range [atom %] 0.55–0.58 9.75–9.99 6.94–7.14 82.29–82.75

Ce

36S

94.454–95.281 0.730–0.793 3.976–4.734 0.013–0.019

Cl 35Cl 37Cl

142Ce

0.185–0.186 0.251–0.254 88.446–88.449 11.114–11.114

75.644–75.923 24.077–24.356

Ca 40Ca 42Ca 43Ca 44Ca 46Ca 48Ca

96.933–96.947 0.646–0.648 0.135–0.135 2.082–2.092 0.004–0.004 0.186–0.188

Nd 142Nd 143Nd 144Nd 145Nd 146Nd 148Nd 150Nd

26.80–27.30 12.12–12.32 23.79–23.97 8.23–8.35 17.06–17.35 5.66–5.78 5.53–5.69

33S 34S

V

50V 51V

Cu 63Cu 65Cu

0.2487–0.2502 99.7498–99.7513 68.983–69.338 30.662–31.017

136Ce 138Ce 140Ce

Pb

204Pb 206Pb 207Pb 208Pb

U

234U 235U 238U

1.04–1.65 20.84–27.48 17.62–23.65 51.28–56.21 0.0050–0.0059 0.7198–0.7207 99.2739–99.2752

28

2 Summary Tables

2.5.3 Isotope Patterns of Naturally Occurring Elements The mass of the most abundant isotope is given under the symbol of the element. The lightest isotope is shown at the left end of the x axis. H 1

He 4

Li 7

Be 9

B 11

C 12

N 14

O 16

F 19

Ne 20

Na 23

Mg 24

Al 27

Si 28

P 31

S 32

Cl 35

Ar 40

K 39

Ca 40

Sc 45

Ti 48

V 51

Cr 52

Mn 55

Fe 56

Co 59

Ni 58

Cu 63

Zn 64

Ga 69

Ge 74

As 75

Se 80

Br 79

Kr 84

Rb 85

Sr 88

Y 89

Zr 90

Nb 93

Mo 98

Ru 102

Rh 103

Pd 106

Ag 107

Cd 114

In 115

Sn 120

Sb 121

Te 130

I 127

Xe 132

Cs 133

Ba 138

La 139

Ce 140

Pr 141

Nd 142

Sm 152

Eu 153

Gd 158

Tb 159

Dy 164

Ho 165

Er 166

Tm 169

Yb 174

Lu 175

Hf 180

Ta 181

W 184

Re 187

Os 192

Ir 193

Pt 195

Au 197

Hg 202

Tl 205

Pb 208

Bi 209

Th 232

U 238



2.5 Mass Spectrometry

29

2.5.4 Calculation of Isotope Distributions The characteristic abundance patterns resulting from the combination of more than one polyisotopic element can be calculated from the relative abundances of the different isotopes. The following polynomial expression gives the isotope distribution of a polyisotopic molecule: {pi1 Α0 + pi2 Α(mi2 - mi1) + pi3 Α(mi3 - mi1) + …}ni ×

{pj1 Α0 + pj2 Α(mj2 - mj1) + pj3 Α(mj3 - mj1) + …}nj × {…

where pix is the relative abundance of the xth isotope of element i, mix is the mass of the xth isotope of the element i, and the exponent ni stands for the number of atoms of the element i in the molecule. The expansion of this polynomial expression after inserting the pix and mix values for all the isotopes 1, 2, 3, … of the elements i, j, … of a given molecule yields an expression that represents the isotope distribution: w0 Α0 + wr Αr + ws Αs + wt Αt + …

where the values of w0, wr, ws, wt, … are the relative abundances of M+·, [M + r]+·, [M + s]+·, [M + t]+·, … , respectively. The use of Α(mix - mi1) allows to determine the values of r, s, t, … simply by expanding the general polynomial. A numerical value for A, which has no intrinsic meaning, is never needed. For example, for CBr2Cl2, the above equation gives rise to the following expression: {p12 Α0 + p13 Α(m13C - m12C ) } × C

{p79

Br

{p35

Cl

0

C

Α + p81

Α0 + p37

Br

Cl

Α(m81Br - m79Br ) }2 ×

Α(m37Cl - m35Cl) }2

For sufficient resolution, (mix - mi1) and (mjx - mj1) differ from one another. This results in very complex isotope patterns even for very small molecules. Thus, owing to the occurrence of 12C, 13C, 79Br, 81Br, 35Cl, and 37Cl, there are 18 signals for CBr2Cl2. However, the limited resolution of many real life experiments can make many pairs of (mix - mi1) and (mjx - mj1) indistinguishable within experimental error, thereby reducing the number of separate peaks. For example, at unit resolution, one obtains (m13 - m12 ) = 1 and (m81 - m79 ) = (m37 - m35 ) = 2. Consequently, C C Br Br Cl Cl the expression for CBr2Cl2 becomes:

30

2 Summary Tables

{p12 Α0 + p13 Α1 } × {p79

Α0 + p81 Α2 }2 × {p35 Α0 C Br Br Cl 2 2 0 p12 p79 p35 } Α + C Br Cl 2 { p13 p79 p235 } Α1 + C Br Cl p12 p79 p81 p235 + p12 p279 p35 p37 } Α2 + C Br Br Cl C Br Cl Cl 2 2 { p13 p79 p81 p35 + p13 p79 p35 p37 } Α3 + C Br Br Cl C Br Cl Cl C

{

{

+ p37

Cl

Α2 }2 =

{ p12 p281

p2 + 4 p12 p79 p81 p35 p37 + p12 p279 p237 } Α4 + Br 35Cl C Br Br Cl Cl C Br Cl 2 2 2 { p13 p81 p35 + 4 p13 p79 p81 p35 p37 + p13 p79 p237 } Α5 C Br Cl C Br Br Cl Cl C Br Cl 2 2 6 p12 p79 p81 p37 + p12 p81 p35 p37 } Α + C Br Br Cl C Br Cl Cl C

{

p p2 C Br 81Br 37Cl p12 p281 p237 } Α8 + C Br Cl 2 { p13 p81 p237 } Α9 C Br Cl { p13 p79

{

+ p13 p281 C

Br

p35 p37 Cl

Cl

+

} Α7 +

This shows that at unit resolution, CBr2Cl2 gives rise to only 10 peaks (M+·, [M+1]+·, [M+2]+·, ... [M+9]+·) rather than 18 peaks, as they would be expected for very high resolution. Moreover, the contribution of isotopes of low abundance can often be neglected without sacrificing much precision. For example, the effect of 2H on isotope patterns is usually insignificant. Also, 13C is often negligible when focussing on peaks of the series [M+2n]+·, which then results in patterns that are characteristic for halogens, sulfur, and silicon. In large molecules, however, isotopes of low abundance cannot be neglected. For example, in the case of buckminster fullerene (C60), not only M+· (relative intensity, 100%) and [M+1]+· (64.80%), but also [M+2]+· (20.65%), [M+3]+· (4.31%), and even [M+4]+· (0.66%) are quite significant ions. With the above algorithm, typical isotope patterns can be readily calculated manually by applying the general equation and neglecting isotopes of low abundance. The outlined procedure can also be easily implemented and evaluated with generic computer software that allows simple calculations. Dedicated and user-friendly programs that already contain the necessary isotope abundances and masses are available. Incidentally, because the use of the above equation for systems with 1000 or more polyisotopic atoms results in excessive calculation times, more efficient but somewhat more complicated algorithms have been developed for implementation in dedicated programs [4]. Typical isotope patterns are given on the following pages.



2.5 Mass Spectrometry

31

2.5.5 Isotopic Abundances of Various Combinations of Chlorine, Bromine, Sulfur, and Silicon Elements

Mass Relative Ele abunments dance

Cl1

35 37

100 31.96

Br1

Cl2

70 72 74

100 63.92 10.21

Cl3

105 107 109 111

Cl4

Cl5

Cl6

Mass Relative Ele abunments dance 79 81

100 97.28

Br2

158 160 162

51.40 100 48.64

100 95.88 30.64 3.26

Br3

237 239 241 243

34.27 100 97.28 31.54

140 142 144 146 148

78.22 100 47.94 10.21 0.82

Br4

316 318 320 322 324

17.61 68.53 100 64.85 15.77

175 177 179 181 183 185

62.53 100 63.92 20.43 3.26 0.21

Br5

395 397 399 401 403 405

10.57 51.40 100 97.28 47.32 9.21

210 212 214 216 218 220 222

52.15 100 79.90 34.05 8.16 1.04 0.06

Br6

474 476 478 480 482 484 486

5.43 31.70 77.10 100 72.96 28.39 4.60

Mass Relative abun dance

S1

32 33 34

100 0.80 4.52

S2

64 65 66 68

100 1.60 9.05 0.20

S3

96 97 98 99 100

100 2.40 13.58 0.22 0.61

S4

128 129 130 131 132

100 3.20 18.12 0.43 1.23

S5

160 161 162 163 164 166

100 4.00 22.66 0.72 2.05 0.09

32 Elements

2 Summary Tables Mass Relative Ele abunments dance 100 5.08 3.35

Si2

Mass Relative Ele abunments dance

Si1

28 29 30

56 57 58 59 60

Cl1Br1

114 116 118

77.38 Cl1Br2 100 24.06

193 195 197 199

Cl1Br4

351 353 355 357 359 361

14.45 60.84 100 79.42 29.94 4.14

Cl2Br1

Cl3Br1

184 186 188 190 192

51.77 100 64.15 17.12 1.64

Cl1S1

67 68 69 70 71

100 0.80 36.48 0.26 1.44

100 10.15 6.95 0.34 0.11

Mass Relative abun dance 84 85 86 87 88

100 15.23 10.82 1.03 0.36

44.14 Cl1Br3 100 69.23 13.35

272 274 276 278 280

26.51 85.85 100 48.46 7.80

149 151 153 155

62.03 100 44.91 6.16

Cl2Br2

228 230 232 234 236

38.69 100 88.68 31.09 3.74

Cl3Br2

263 265 267 269 271 273

32.07 93.14 100 49.27 11.34 0.99

Cl4Br1

219 221 223 225 227 229

44.42 100 82.47 32.28 6.11 0.45

Cl1S2

99 100 101 102 103

100 1.60 41.01 0.58 3.10

Cl2S1

102 103 104 105 106 108

100 0.80 68.44 0.51 13.10 0.46

Si3



2.5 Mass Spectrometry Elements

Mass Relative Ele abunments dance

Cl1Si1

63 64 65 66 67

100 5.08 35.31 1.62 1.07

Mass Relative Ele abunments dance

Cl2Si1

98 99 100 101 102 103 104

100 5.08 67.27 3.25 12.35 0.52 0.34

33

Mass Relative abun dance

Cl3Si1

133 134 135 136 137 138 139

100 5.08 99.23 4.87 33.85 1.56 4.29

2.5.6 Isotope Patterns of Combinations of Cl and Br

The signals are separated by 2 mass units. The mass for the most abundant signal is shown under the symbol of the element. The combination of the lightest isotopes is given on the left side of the x axis. See Chapter 2.5.5 for exact abundances of many of these combinations. Signals separated by 2 units

Br 79

Br2 160

Br3 239

Br4 320

Br5 399

Cl 35

ClBr 116

ClBr2 195

ClBr3 276

ClBr4 355

ClBr5 436

Cl2 70

Cl2Br 151

Cl2Br2 230

Cl2Br3 311

Cl2Br4 390

Cl2Br5 471

Cl3 105

Cl3Br 186

Cl3Br2 267

Cl3Br3 346

Cl3Br4 427

Cl4 142

Cl4Br 221

Cl4Br2 302

Cl4Br3 381

Cl4Br4 462

Cl5 177

Cl5Br 256

Cl5Br2 337

Cl5Br3 418

Cl6 212

Cl9 319

Cl12 426

Br6 480

Br9 718

34

2 Summary Tables

2.5.7 Indicators of the Presence of Heteroatoms In low-resolution mass spectra, one often observes characteristic isotope patterns, specific masses of fragment ions, and characteristic mass differences (Δm) between the molecular ion (M+·) and fragment ions (frag+) or between fragment ions. High resolution mass spectra can be used to confirm the elemental composition provided that the resolution is sufficient to discriminate alternative compositions. Moreover, tandem mass spectrometry (also called MS/MS) may be used to identify characteristic losses of heteroatoms from parent or fragment ions. Indication of O:

Δm 17 from M+·, in N-free compounds Δm 18 from M+· Δm 18 from frag+, particularly in aliphatic compounds Δm 28, 29 from M+· for aromatic compounds Δm 28 from frag+ for aromatic compounds m/z 15, relatively abundant m/z 19 m/z 31, 45, 59, 73, … + (14)n m/z 32, 46, 60, 74, … + (14)n m/z 33, 47, 61, 75, … + (14)n for 2 × O, in the absence of S m/z 69 for aromatic compounds meta-disubstituted by O

Indication of N:

M+· odd-numbered (indicates odd number of N in M+·) Large number of even-numbered fragment ions Δm 17 from M+· or frag+, in O-free compounds Δm 27 from M+· or frag+, for aromatic compounds or nitriles Δm 30, 46 for nitro compounds m/z 30, 44, 58, 72, … + (14)n for aliphatic compounds

Indication of S:

Isotope peak [M+2]+· ≥ 5% of M+· Δm 33, 34, 47, 48, 64, 65 from M+· Δm 34, 48, 64 from frag+ m/z 33, 34, 35 m/z 45 in O-free compounds m/z 47, 61, 75, 89, … + (14)n unless compound with 2 × O m/z 48, 64 for S-oxides

Indication of F:

Δm 19, 20, 50 from M+· Δm 20 from frag+ m/z 20 m/z 57 without m/z 55 in aromatics



2.5 Mass Spectrometry

35

Indication of Cl: Isotope peak [M+2]+· ≥ 33% of M+· Δm 35, 36 from M+· Δm 36 from frag+ m/z 35/37, 36/38, 49/51 Indication of Br: Isotope peak [M+2]+· ≥ 98% of M+· Δm 79, 80 from M+· Δm 80 from frag+ m/z 79/81, 80/82 Indication of I: Isotope peak [M+1]+ of very low abundance at relatively high mass Δm 127 from M+· Δm 127, 128 from frag+ m/z 127, 128, 254 Indication of P: m/z 47 in compounds without S or 2 × O m/z 99 without isotope peak at m/z 100 in alkyl phosphates

36

2 Summary Tables

2.5.8 Rules for Determining the Relative Molecular Weight (Mr) The molecular ion (M+·) is defined as the ion that comprises the most abundant isotopes of the elements in the molecule. Interestingly, the lightest isotopes of most elements frequently occurring in organic compounds and their common salts (H, C, N, O, F, Si, P, S, Cl, As, Br, I, Na, Mg, Al, K, Ca, Rb, Cs) are also the most abundant ones. Notable exceptions are B, Li, Se, Sr, and Ba. M+· is always accompanied by isotope peaks. Their relative abundance depends on the number and kind of the elements present and their natural isotopic distribution. The abundance of [M+1]+· indicates the maximum number of carbon atoms (Cmax) according to the following relationship: Cmax = 100 × intensity([M + 1]+·) / {1.1 × intensity(M+·)}

The intensities of [M + 2]+· and higher masses are indicative of the number and kind of elements that have a relatively abundant heavier isotope (such as S, Si, Cl, Br). Note that, in the presence of one of these elements, in analogy to the calculation of Cmax, the ratio of the intensities of [M + 2]+· and M+· for a compound with n silicon, o sulfur, p chlorine, or q bromine atoms can be approximated with quite high accuracy from n × 3.35%, o × 4.52%, p × 31.96%, or q × 97.28%, respectively (see also Chapters 2.5.4 to 2.5.6). The mass of M+· is always an even number if the molecule contains only elements for which the atomic mass and valence are both even- (C, O, S, Si) or both odd-numbered (H, P, F, Cl, Br, I). In the presence of other elements (e.g., 14N) and isotope labels (e.g., 13C, 2H), M+· becomes an odd number if those elements are present in an odd number. The molecular ion can only form fragment ions of masses that differ from that of M+· by chemically logical values (Δm). In this context, chemically illogical differences are Δm = 3 (in the absence of Δm = 1) to Δm = 14, Δm = 21 (in the absence of Δm = 1) to Δm = 24, Δm = 37, 38, and all Δm less than the mass of an element of characteristic isotope pattern in cases where the same isotope pattern is not retained in the fragment ion. M+· must contain all elements (and the maximum number of each) that are shown to be present in the fragment ions. If ionization is performed by electron impact, M+· is the ion with the lowest appearance potential. If a pure sample flows into the ion source through a molecular leak, M+· exhibits the same effusion rate as can be determined from the fragment ions. The abundance of M+· is proportional to the sample pressure in the ion source. For polar compounds, [M + H]+ is often observed in mass spectra obtained not only with fast atom bombardment and atmospheric pressure chemical ionization but also with electron impact ionization. In this latter case, the abundance of [M + H]+ changes in proportion to the square of the sample pressure in the ion source. In the absence of a signal for M+·, the relative molecular weight must have a value that shows a logical and reasonable mass difference, Δm, to all the observed fragment ions.



2.5 Mass Spectrometry

37

Various adducts may be formed with soft ionization methods (chemical ionization, ESI, MALDI): [M+H]+ [M+Li]+ [M+NH4]+ [M+H+H2O]+ [M+Na]+ [M+H+CH3OH]+ [M+K]+ [M+H+CH3CN]+

M+1 M+7 M + 18 M + 19 M + 23 M + 33 M + 39 M + 42

[M+H+H2O+CH3OH]+ [M+Na+CH3CN]+ [2M+H]+ [2M+Na]+ [2M+K]+ [3M+Na]+ [3M+K]+

M + 51 M + 64 2M + 1 2M + 23 2M + 39 3M + 23 3M + 39

2.5.9 Homologous Mass Series as Indications of Structural Type Certain sequences of intensity maxima in the lower mass range and the masses of unique signals are often characteristic of a particular compound type. The intensity distribution of such ion series is in general smooth. Therefore, abrupt changes (maxima and minima) are of structural significance. The ion or ion series most indicative of a particular compound type is set in italics. ­ Mass Elemental values, m/z composition 12 + 14n

CnH2n-2

13 + 14n

CnH2n-1

14 + 14n

CnH2n-3O CnH2n

15 + 14n

CnH2n-2O CnH2n+1

CnH2n-1O

Compound types alkenes, monocycloalkanes, alkynes, dienes, cycloalkenes, polycyclic alicyclics, cyclic alcohols alkanes, alkenes, monocycloalkanes, alkynes, dienes, cycloalkenes, polycyclic alicyclics, alcohols, alkyl ethers, cyclic alcohols, cycloalkanones, aliphatic acids, esters, lactones, thiols, sulfides, glycols, glycol ethers, alkyl chlorides cycloalkanones alkanes, alkenes, monocycloalkanes, polycyclic alicyclics, alcohols, alkyl ethers, thiols, sulfides, alkyl chlorides cycloalkanones alkanes, alkenes, monocycloalkanes, alkynes, dienes, cycloalkenes, polycyclic alicyclics, alkanones, alkanals, glycols, glycol ethers, alkyl chlorides, acid chlorides alkanones, alkanals, cyclic alcohols, carboxylic acid chlorides

38

2 Summary Tables

Mass values m/z 16 + 14n 17 + 14n 18 + 14n 19 + 14n

20 + 14n 21 + 14n

22 + 14n 23 + 14n 24 + 14n 25 + 14n

Elemental composition CnH2nO CnH2n+2N CnH2nNO CnH2n+1O

CnH2n-1O2 CnH2nO2 CnH2n+3O CnH2n+1O2 CnH2n+1O2 CnH2n+1S C8H8 + CnH2n CnH2n+2O2 CnH2n+2S C7H7 + CnH2n C7H5O CnH2nCl CnH2nCOCl C6H6N + CnH2n CnH2n–6 CnH2n–5 CnH2n–4 CnH2n–3

39, 52±1, CnHn±1 64±1, 76±2, 91±1

Compound types alkanones, alkanals alkyl amines, aliphatic amides aliphatic amides alcohols, alkyl ethers, aliphatic carboxylic acids, esters, lactones, glycols, glycol ethers aliphatic carboxylic acids, esters, lactones aliphatic carboxylic acids, esters, lactones alcohols, alkyl ethers aliphatic carboxylic acids, esters, lactones glycols, glycol ethers thiols, sulfides alkylbenzenes glycols, glycol ethers thiols, sulfides alkylbenzenes aryl ketones alkyl chlorides acid chlorides alkylanilines polycyclic alicyclics polycyclic alicyclics polycyclic alicyclics alkynes, dienes, cycloalkenes, polycyclic alicyclics alkylbenzenes, aromatic hydrocarbons, phenols, aryl ethers, aryl ketones



2.5 Mass Spectrometry

39

2.5.10 Mass Correlation Table Note: As long as it makes sense chemically, CH2, CH4, CH3O, and O2 in the formulae of the second column may be replaced by N, O, P, and S, respectively (M, molar mass). Mass Ion

Product ion (and neutral particle lost)

Substructure or compound type

1

[M+1]+

particularly in ESI spectra, in which M±1 occurs even for moderately basic and acidic compounds, but intensive M+· without M±1 is unusual in ESI spectra in the presence of Li+ (with isotope signal for 6Li)

7

Li+·

12 13 14

C+· CH+ CH2+·, N+, N2++, CO++ CH3+ [M-15]+·

15 16

O+·, NH2+, O2++

17

OH+, NH3+·

18

H2O+·, NH4+

19 20

H3O+, F+ HF+·, Ar++, CH2CN++ C2H2O++ CO2++

21 22

[M+7]+

(CH3) nonspecific; abundant: methyl, N-ethylamines [M-16]+· (CH4) methyl (rare) (O) nitro compounds, sulfones, epoxides, N-oxides (NH2) primary amines [M-17]+· (OH) carboxylic acids (especially aromatic ones), hydroxylamines, N-oxides, nitro compounds, sulfoxides, tertiary alcohols (NH3) primary amines [M-18]+· (H2O) nonspecific; abundant: alcohols, some acids, aldehydes, ketones, lactones, cyclic ethers O indicator [M-19]+ (F) fluoro compounds F indicator + · [M-20] (HF) fluoro compounds F indicator

40

2 Summary Tables

Mass Ion

23

Na+

24 25 26

+·

27 28

29 30

31

32

C2 C2H+ C2H2+·, CN+

Product ion (and neutral particle lost)

Substructure or compound type

[M+23]+

in ESI spectra in the presence of Na+; sometimes strong even if Na+ is only an impurity in ESI spectra of organic Na+ salts

[M-23]+ [M-25]+ (C2H) [M-26]+· (C2H2) (CN) [M-27]+ (C2H3)

terminal acetylenyl aromatics nitriles + C2H3 , terminal vinyl, some ethyl esters and HCN+· N-ethylamides, ethyl phosphates + · [M-27] (HCN) aromatic N, nitriles C2H4+·, CO+·, [M-28]+· (C2H4) nonspecific; abundant: cyclo­hexenes, N2+·, HCNH+ ethyl esters, propyl ketones, propylsubstituted aromatics (CO) aromatic O, quinones, lactones, lactams, unsaturated cyclic ketones, allyl aldehydes (N2) diazo compounds; air (inten­sity 3.7 times larger than for O2+·, m/z 32) + + + C2H5 , CHO [M-29] (C2H5) nonspecific; abundant: ethyl (CHO) phenols, furans, aldehydes CH2O+·, [M-30]+· (C2H6) ethylalkanes, polymethyl compounds CH2NH2+, (CH2O) cyclic ethers, lactones, primary NO+, C2H6+·, alcohols BF+·, N2H2+· (NO) nitro and nitroso compounds N indicator + + CH3O , [M-31] (CH3O) methyl esters, methyl ethers, primary CH3NH2+·, alcohols O indicator CF+, N2H3+ (CH3NH2) N-methylamines (N2H3) hydrazides O2+·, [M-32]+· (O2) cyclic peroxides; air (intensity 3.7 + · CH3OH , times smaller than for N2+·, m/z 28) + + · · N2H4 , S (CH3OH) methyl esters, methyl ethers O indicator (S) sulfides (with 34S isotope signal)



2.5 Mass Spectrometry Mass Ion

33

CH3OH2+, SH+, CH2F+

34

SH2+·

35

SH3+, Cl+

36

HCl+·, C3+

37

C3H+ 37Cl+

38 39

C3H2+· C3H3+ K+

40 41

42

43

Product ion (and neutral particle lost) [M-33]+

41

Substructure or compound type

(SH)

nonspecific (with isotope signal for 34S) S indicator (CH3 + H2O) nonspecific O indicator (CH2F) fluoromethyl [M-34]+· (SH2) nonspecific (with 34S isotope signal) S indicator (OH + OH) nitro compounds [M-35]+ (Cl) chloro compounds (with 37Cl isotope signal) (OH + H2O) nitro compounds 2 × O indicator + · [M-36] (HCl) chloro compounds (H2O + H2O) 2 × O indicator chloro compounds (with isotope signal for 35Cl) [M-39]+ (C3H3) [M+39]+

[M-39]+ C3H4+·, Ar+·, [M-40]+· CH2CN+ (CH2CN) C3H5+, [M-41]+ (C3H5) + · CH3CN (CH3CN) C3H6+·, C2H2O+·, CON+, C2H4N+

[M-42]+· (C3H6)

C3H7+, C2H3O+, CONH+·

[M-43]+ (C3H7)

(C2H2O)

(CH3CO)

aromatics in ESI spectra often strong even if K+ is only an impurity (with isotope signal for 41K) in ESI spectra of organic K+ salts cyanomethyl alicyclics (especially polyalicyclics), alkenes 2-methyl-N-aromatics, N‑methylanilines nonspecific; abundant: propyl esters, butyl ketones, butylaromatics, methylcyclohexenes acetates (especially enol acetates), acetamides, cyclohexenones, α,β‑unsaturated ketones nonspecific; abundant: propyl, alicyclics, cycloalkanones, cycloalkylamines, cycloalkanols, butylaromatics methyl ketones, acetates, aromatic methyl ethers

42

2 Summary Tables

Mass Ion

44

45

46

47

48

49 50 51

Product ion (and neutral particle lost)

CO2+·, [M-44]+· (C3H8) + C2H6N , (C2H6N) C2H4O+·, (C2H4O) CS+·, C3H8+·, CH4Si+· (CO2)

Substructure or compound type

propylalkanes N,N-dimethylamines, N-ethylamines cycloalkanols, cyclic ethers, ethylene ketals, aliphatic aldehydes (McLafferty rearrangement) anhydrides, lactones, carboxylic acids + + C2H5O , [M-45] (C2H5O) ethyl esters, ethyl ethers, lactones, C2H7N+·, ethyl sulfonates, ethyl sulfones CHS+ (with (CHO2) carboxylic acids isotope signal (C2H7N) N,N-dimethylamines, N-ethylamines for 34S) O indicator S indicator + + · · C2H5OH , [M-46] (C2H6O) ethyl esters, ethyl ethers, ethyl NO2+ sulfonates (H2O + C2H4) primary alcohols (H2O + CO) carboxylic acids (NO2) nitro compounds CH3S+, CCl+, [M-47]+ (CH3S) methyl sulfides (with isotope signal C2H5OH2+, for 34S) CH(OH)2+, 2 × O indicator PO+ S indicator P indicator CH3SH+·, [M-48]+· (CH4S) methyl sulfides (with 34S isotope SO+·, CHCl+· signal) (SO) sulfoxides, sulfones, sulfonates (with 34S isotope signal) CH2Cl+, [M-49]+ (CH2Cl) chloromethyl (with 37Cl isotope signal) CH3SH2+ (with 34S iso­tope sig­nal) + + C4H2 ·, [M-50] · (CF2) trifluoromethylaromatics, perfluoroCH3Cl+·, alicyclics CF2+· C4H3+, CHF2+



2.5 Mass Spectrometry Mass Ion

52 53 54 55 56

57 58

C4H4+· C4H5+ C4H6+·, C2H4CN+ C4H7+, C3H3O+ C4H8+·, C3H4O+· C4H9+, C3H5O+, C3H2F+ C3H8N+, C3H6O+·

59

C3H7O+, C2H5NO+·

60

C2H4O2+·, CH2NO2+, C2H6NO+ , C2H4S+· C2H5O2+, C2H5S+

61

62

63 64

43

Product ion (and neutral particle lost)

Substructure or compound type

[M-54]+· (C4H6) (C2H4CN) [M-55]+ (C4H7)

cyclohexenes cyanoethyl nonspecific; abundant: alicyclics, butyl esters, N-butylamides butyl esters, N-butylamides, pentyl ketones, cyclohexenes, tetralins, pentylaromatics methylcyclohexenones, β-tetralones nonspecific ethyl ketones

[M-56]+· (C4H8) (C3H4O) [M-57]+ (C4H9) (C3H5O) [M-58]+· (C4H10) (C3H6O) [M-59]+ (C3H7O) (C2H3O2) (C3H9N) [M-60]+· (C3H8O) (C2H4O2) (CH3OH + CO) (C2H4S) [M-61]+ (C2H5O2) (C2H5S)

C2H6O2+·, C2H3Cl+· C2H6S+·

[M-62]+· (C2H6O2)

C5H3+, C2H4Cl+, COCl+ C5H4+·, SO2+·, S2+·

[M-63]+ (C2H4Cl) (CO + Cl)

(C2H6S)

[M-64]+· (SO2) (S2)

alkanes N indicator α-methylalkanals, methyl ketones, isopropylidene glycols O indicator propyl esters, propyl ethers methyl esters O indicator amines, amides propyl esters, propyl ethers acetates methyl esters O indicator glycols, ethylene ketals 2 × O indicator ethyl sulfides (with 34S isotope signal) S indicator methoxymethyl ethers, ethylene glycols, ethylene ketals ethyl sulfides (with 34S isotope signal) chloroethyl carboxylic acid chlorides (with 37Cl isotope signal) sulfones, sulfonates disulfides (with 34S isotope signal)

44

2 Summary Tables

Mass Ion

65 66 67 68 69

70 71 72 73 74 75

C5H5+, H2PO2+ C5H6+· S2H2+·

C5H7+, C4H3O+ C5H8+·, C4H4O+·, C3H6CN+ C5H9+, C4H5O+, C3HO2+ CF3+ C5H10+· C4H6O+· C4H8N+ C5H11+ C4H7O+ C4H8O+·

C4H10N+ C6+· C4H9O+ C3H5O2+ C3H9Si+ C4H10O+· C3H6O2+· C3H7O2+ C3H7S+

76 77

C2H7SiO+ C6H4+· C6H5+ C3H6Cl+

Product ion (and neutral particle lost)

Substructure or compound type

[M-65]+ (S2H) (SO2H) [M-66]+· (C5H6)

disulfides

[M-67]+ (C4H3O)

cyclopentenes disulfides (with 34S isotope signal) furyl ketones

[M-68]+· (C5H8) (C4H4O)

cyclohexenes, tetralins cyclohexenones, β-tetralones

[M-69]+ (C5H9)

alicyclics, alkenes

(CF3)

trifluoromethyl alkanes, alkenes, alicyclics cycloalkanones pyrrolidines alkanes, larger alkyl groups alkanones, alkanals, tetrahydrofurans alkanones, alkanals O indicator aliphatic amines N indicator perhalogenated benzenes alcohols, ethers, esters O indicator carboxylic acids, esters, lactones trimethylsilyl compounds ethers methyl esters of carboxylic acids, α-methyl carboxylic acids methyl acetals, glycols 2 × O indicator 34 sulfides, thiols (with S isotope signal) S indicator trimethylsilyloxyl compounds aromatics aromatics chloro compounds (with 37Cl isotope signal)



2.5 Mass Spectrometry

Mass Ion 78 79 80

81 82

83 84 85

86 87 88 89 90 91

+·

C6H6 C5H4N+ C3H7Cl+· C6H7+ C5H5N+· Br+ C6H8+· C5H4O+· HBr+· C5H6N+ C6H9+ C5H5O+ 81Br+ C6H10+· C5H6O+·

C5H8N+ C4H6N2+· CCl2+· C6H11+ C5H7O+ C5H10N+ C6H13+ C5H9O+ CClF2+ C5H10O+· C5H12N+ C5H11O+ C4H7O2+ C4H8O2+· C4H9O2+ C4H9S+ C7H6+· C7H7+ C4H8Cl+

Compound type

45

aromatics pyridines chloro compounds (with 37Cl isotope signal) aromatics with H-containing substituents pyridines, pyrroles bromo compounds (with 81Br isotope signal) cyclohexenes, polycyclic alicyclics cyclopentenones bromo compounds (with 81Br isotope signal) pyrroles, pyridines cyclohexanes, cyclohexenyls, dienes furans, pyrans bromo compounds (with 79Br isotope signal) cyclohexanes cyclopentenones, dihydropyrans tetrahydropyridines pyrazoles, imidazoles chloro compounds (with isotope signals at m/z 84 and 86) alkenes, alicyclics, monosubstituted alkanes cycloalkanones piperidines, N-methylpyrrolidines alkanes alkanones, alkanals, tetrahydropyrans, fatty acid derivatives chlorofluoroalkanes (with 37Cl isotope signal) alkanones, alkanals aliphatic amines N indicator alcohols, ethers, esters O indicator esters, carboxylic acids ethyl esters of carboxylic acids, α-methyl-methyl esters, α-C2-carboxylic acids diols, glycol ethers 2 × O indicator sulfides (with 34S isotope signal) disubstituted aromatics aromatics alkyl chlorides (with 37Cl isotope signal)

46

2 Summary Tables

Mass Ion 92 93 94 95 96 97 98 99

104 105 106 111 115 119

120 121

+·

C7H8 C6H6N+ C6H5O+ C6H7N+·

CH2Br+ C6H6O+· C5H4NO+ C5H3O2+ C7H12+· C7H13+ C6H9O+ C5H5S+ C6H12N+ C7H15+ C6H11O+ C5H7O2+ H4PO4+ C8H8+· C7H4O+·

C8H9+ C7H5O+ C6H5N2+ C7H8N+ C5H3OS+ C9H7+ C6H11O2+ C5H7O3+ C9H11+ C8H7O+ C2F5+ C7H5NO+· C7H4O2+·

C8H10N+ C8H9O+ and C7H5O2+

Compound type

alkylbenzenes alkylpyridines phenols, phenol derivatives anilines bromo compounds (with 81Br isotope signal) phenol esters, phenol ethers pyrryl ketones, pyridone derivatives furyl ketones alicyclics alicyclics, alkenes cycloalkanones alkylthiophenes (with 34S isotope signal) N-alkylpiperidines alkanes alkanones ethylene ketals alkyl phosphates tetralin derivatives, phenylethyl derivatives disubstituted α-ketobenzenes alkylaromatics benzoyl derivatives diazophenyl derivatives alkylanilines thiophenoyl derivatives (with 34S isotope signal) aromatics esters diesters alkylaromatics tolyl ketones perfluoroethyl derivatives phenyl carbamates γ-benzopyrones, salicylic acid derivatives pyridines, anilines hydroxybenzene derivatives



2.5 Mass Spectrometry

Mass Ion 127

128

130 131 135 141 142 149 152 165 167 205 223

+

C10H7 C6H7O3+ C6H6NCl+· I+ C10H8+· C6H5OCl+· HI+· C9H8N+ C9H6O+· C10H11+ C5H7S2+ C3F5+ C4H8Br+ C11H9+ C10H8N+ C8H5O3+ C12H8+·

C13H9+ C8H7O4+ C12H13O3+ C12H15O4+

Compound type

naphthalenes unsaturated diesters chlorinated N-aromatics (with 37Cl isotope signal) iodo compounds naphthalenes chlorinated hydroxybenzene derivatives (with 37Cl isotope signal) iodo compounds quinolines, indoles naphthoquinones tetralins thioethylene ketals (with 34S isotope signal) perfluoroalkyl derivatives alkyl bromides (with 81Br isotope signal at m/z 137) naphthalenes quinolines phthalates diphenyl aromatics diphenylmethane derivatives (fluorenyl cation) phthalates phthalates phthalates

47

48

2 Summary Tables

2.5.11 Common Fragmentations of [M+H]+ in ESI- and API-MS/ MS-Spectra [5–7] The loss of neutral species is the predominant fragmentation of [M+H]+ in MS/ MS spectra. Good leaving groups are the same as in EI-spectra. Additionally, in contrast to EI-spectra, the cleavage of R–X (X = O, N, S) bonds in amines, ethers and sulfides is a common process. It leads either by elimination of an alcohol, an amine, or a thiol to R+ or by elimination of an alkene (R-H) to a protonated alcohol, amine, or thiol.

Mass Formula 15 CH3· 16

CH4

17

O NH2· OH·

18

H2O

20 26 27 28

HF C2H2 HCN C2H4 CO

29 30

31 32 33 34 35

NH3

N2 CH2=NH CH2=O NO· CH O· 3

CH3NH2 HNO CH3OH S CH3· + H2O H2O2 SH2 Cl·

Compound type

tert-butyl groups, aromatic methyl ethers and N-methyl amines, methyl ammonium quaternary ammonium compounds, aromatic dimethyl ethers N-oxides aromatic amines N-oxides, aromatic nitro compounds, sulfoxides primary amines and amides, cyclic amines, amino acids, oximes alcohols, phenols, epoxides, aldehydes, ketones, carboxylic acids, esters, nitro compounds, N-oxides fluoro compounds aromatic compounds N-heteroaromatics, amines, oximes, aromatic nitriles compounds with X–CH2CH3 groups (X = O, N, S) phenols, aldehydes, ketones, carboxylic acids, aromatic nitro compounds azo compounds secondary methyl amines, piperazines aromatic methoxy compounds, benzyl alcohols aromatic nitro compounds, nitroso compounds aromatic methoxy compounds aliphatic methyl amines aromatic nitro compounds methyl ethers, methyl esters S-heteroaromatics nonspecific hydroperoxides thiols chloro compounds



2.5 Mass Spectrometry Mass Formula 36 41 42 43 44 45 46 47 48 50 54 56 57 58 59 60

61 64 66 68

HCl H2O + H2O CH3CN C3H6 CH2C=O CN2H2 C3H7· C2H5N CONH CO2 CH3CHO H2O + HCN (CH3)2NH CH3CH2NH2 C2H5OH H2O + CO NO2· HNO2 CH3S· CH3SH SO CH3Cl CF2 C4H6 C4H8 C3H7N C2H3NO NO· + CO C3H7NH2 C3H7OH C3H6 + H2O CH3COOH CH2C=O + H2O CO2 + NH3 SO2 S2 SO2 + H2 C4H4O C3H4N2

49

Compound type

chloro compounds dihydroxy compounds methyl-substituted N-heteroaromatics O- and N-propyl compounds acetyl compounds, ethyl ketones N-heteroaromatics, diamines, guanidines isopropyl derivatives secondary N-methyl amines, piperazines cyclic amides, carbamates anhydrides, aromatic carboxylic acids, carbamates N–CH2CH2OH derivatives aliphatic dimethyl amines N-ethyl amines, piperidines ethyl ethers, ethyl esters aliphatic carboxylic acids, amino acids aromatic nitro compounds aromatic nitro compounds aromatic methyl thioethers thioethers aromatic sulfonyl compounds trifluoromethyl derivatives O- and N-butyl compounds aliphatic N-ethyl-N-methy groups, N-methylpiperazines N-methyl carbamates, glycyl aromatic nitro compounds N-propyl- and N-isopropyl derivatives propyl ethers and propyl esters acetic acid esters amino acids sulfones, sulfonic acids, sulfonates disulfides sulfonamides cyclohexanones imidazoles

50

2 Summary Tables

Mass Formula 71 74 73 74 78 79 80 81 82 85 87 93 97 99 101 103 104 113 114 115 126 127 128 129 131 136 137 142 147 154 156 163 176 186

C3H5NO NO2 + CO C4H11N C3H6O2 C6H6 C5H5N Br· HBr SO3 HSO3· C6H10 C5H11N C4H9NO C3H5NO2 C6H7N C5H7NO C5H9NO C4H7NO2 C3H5NOS C8H8 C6H11NO C4H6N2O2 C4H5NO3 C2H7O4P I· HI C6H12N2O C5H6NO3 C5H7NO3 C5H9NOS C4H9PO3 C6H7N3O C2H7PO3S C9H9NO C4H11PO4 C6H12N4O C9H9NO2 C6H8O6 C11H10N2O

Compound type

alanyl aromatic nitro compounds N-tert-butyl ethyl esters phenyl derivatives pyridine derivatives bromo compounds bromo compounds sulfonic acids sulfonic acids cyclohexane derivatives piperidine derivatives morpholine derivatives seryl aniline derivatives prolyl valyl threonyl cysteinyl ethylbenzene derivatives leucyl, isoleucyl asparaginyl aspartic dimethyl phosphates iodo compounds iodo compounds lysyl glutaminyl glutanyl methionyl aryl diethyl phosphates histidyl dimethyl phosphorothionates phenylalanyl diethyl phosphates arginyl tyrosinyl glucuronic acid derivatives tryptophanyl



2.5 Mass Spectrometry

51

2.5.12 References [1] M.E. Wieser, Atomic weights of the elements 2005, J. Phys. Chem. Ref. Data 2007, 36, 485. [2] G. Audi, A.H. Wapstra, The AME2003 atomic mass evaluation, (II). Tables, graphs and references, Nucl. Phys. A 2003, 729, 337. [3] J.K. Böhlke, J.R. de Laeter, P. De Bièvre, H. Hidaka, H.S. Peiser, K.J.R. Rosman, P.D.P. Taylor, Isotopic compositions of the elements, 2001, J. Phys. Chem. Ref. Data 2005, 34, 57. [4] H. Kubinyi, Calculation of isotope distributions in mass spectrometry. A trivial solution for a non-trivial problem, Anal. Chim. Acta 1991, 247, 107. [5] W.M.A. Niessen, R.A. Correa C., Interpretation of MS-MS Mass Spectra of Drugs and Pesticides, Wiley, Hoboken, 2017. [6] M. Holcapek, R. Jirásko, M. Lisa, Basic rules for the interpretation of atmospheric pressure ionisation mass spectra of small molecules, J. Chromatogr. A, 2010, 1217, 3908. [7] K. Levsen, H.-M. Schiebel, J.K. Terlouw, K.J. Jobst, M. Elend, A. Preiss, H. Thiele, A. Ingendoh, Even-electron ions: a systematic study of the neutral species lost in the dissociation of quasi-molecular ions, J. Mass Spectrom. 2007, 42, 1024.

52

2 Summary Tables

2.6 UV/Vis Spectroscopy UV/Vis Absorption Bands of Various Compound Types (Α: alkyl or H; R: alkyl; sh: shoulder) Compound Type Transition (log ε) π→π

(3–4)

n→σ

(3.6)

n→σ

(2.4)

π→π

(3.7–4)

n→σ

(2.5)

n→σ π→π n→π π→π n→π n→σ

200

300

400

500

600

700 nm

200

300

400

500

600

700 nm

(3.5)

(3–4) (1–2) (2) (0.9–1.4) (3.5)

n→σ n→σ n→σ n→σ n→σ n→σ

(3.2) (2.2 sh) (3–3.6) (2–3 sh) (3–4) (2.6)

n→σ

(2.5)

n→π

(1.7)

n→π

(1.7)

n→π

(1.8)

π→π n→π

(≈4) (1–2)

π→π

(3.9–4.4)

π→π

(4.2–4.8)

π→π

(4.3–5.2)



2.6 UV/Vis Spectroscopy

Compound Type Transition (log ε) R Cl

O

400

500

600

n→π* (1.7) n=0–4

R I

300

200

(4 – 5)

a

n→σ* (2.6) (2.0) (1.3)

R NO

n=0–4

(2.4–4.1)

a n→π* (conjugated systems) n→π* π→π* (conjugated systems) π→π* n→σ*

a longest

wavelength absorption maximum

53 700 nm

3 Combination Tables

3.1 Alkanes, Cycloalkanes

13C

1H

IR MS

Assignment CH3 CH2 CH C

Range 5–35 ppm 5–45 ppm 25–60 ppm 30–60 ppm

CH3 CH2 CH

0.8–1.2 ppm 1.1–1.8 ppm 1.1–1.8 ppm

CH st CH3 δ as CH2 δ CH3 δ sy CH2 γ

Fragments

UV

Lower shift values in three-membered rings

3000–2840 cm-1 Higher frequency in three-membered rings ≈1460 cm-1 ≈1460 cm-1 ≈1380 cm-1 Doublet for geminal methyl groups 770–720 cm-1 In C–(CH2)n–C with n ≥ 4 at ≈720 cm-1

Molecular ion m/z 14n + 2

Rearrangements

Comments CH3, CH2, CH, and C can be differentiated by multipulse experiments (DEPT, APT), off-resonance decoupling, 2D CH correlation spectra, or based on relaxation times Lower shift values in three-membered rings

m/z 14n m/z 14n - 2

Weak in n-alkanes Very weak in isoalkanes n-Alkanes: local maxima at 14n + 1, intensity variations: smooth, minimum at [M-15]+ Isoalkanes: local maxima at 14n + 1, intensity distribution: irregular (relative maxima due to fragmentation at branching points with charge retention at the most highly substituted C) n-Alkanes: unspecific Isoalkanes: elimination of alkanes Monocycloalkanes: elimination of alkanes No absorption above 200 nm

© The Author(s), under exclusive license to Springer-Verlag GmbH, DE, part of Springer Nature 2020 E. Pretsch et al., Structure Determination of Organic Compounds, https://doi.org/10.1007/978-3-662-62439-5_3

55

56 3 Combination Tables

3.2 Alkenes, Cycloalkenes

13C

Assignment C=C C–(C=C)

Range 100–150 ppm 10–60 ppm

Comments Considerable differences between Z and E: C

X

C

H

1H

H–(C=C) CH3–(C=C) CH2–(C=C)

4.5–6.5 ppm ≈1.7 ppm ≈2.0 ppm

H



X

Coupling constants: |Jgem| 0–3 Hz Jcis 5–12 Hz Jtrans 12–18 Hz Coupling constants: 3JCH3–CH=C ≈ 7 Hz 3JCH –CH=C ≈ 7 Hz 2 H In rings, |J| smaller: n = 2, 3J ≈ 0.5 Hz H n = 3, 3J ≈ 1.5 Hz H n = 4, 3J ≈ 4.0 Hz C n

Long-range coupling, 4JHC–C=CH 0–2 Hz

IR

H–C(=C) st 3100–3000 cm-1 C=C st 1690–1635 cm-1 Of variable intensity H–C(=C) δ oop 1000–675 cm-1 CH2–(C=C) δ 1440 cm-1

MS Molecular ion Fragments

m/z 14n m/z 14n - 2 m/z 14n - 1 m/z 14n - 3

Rearrangements

Alkenes: moderate intensity Monocycloalkenes: medium intensity Local maxima for alkenes Local maxima for monocyclic alkenes Usually, double bonds cannot be localized n-Alkenes: unspecific except for: +.

R

R H

X

R

- X C H =CH 2

R

R

+.

H

R

Cyclohexenes: retro-Diels–Alder reaction: +

UV

C=C π   π*

< 210 nm (log ε 3–4) (C=C)2 π   π* 215–280 nm (log ε 3.5–4.5)



.

+ +

.

Isolated double bonds; for highly substituted double bonds often absorption tail



3.3 Alkynes

57

3.3 Alkynes

13C

1H

IR

Assignment C ––– C C–(C ––– C) H–(C ––– C) CH3–(C ––– C) CH2–(C ––– C) CH–(C ––– C) H–C(––– C) st C ––– C st

MS Molecular ion

UV

Fragments Rearrangements C ––– C π   π*

Range 65–85 ppm

0–30 ppm

1.5–3.0 ppm ≈1.8 ppm ≈2.2 ppm ≈2.6 ppm

Comments Coupling constant, 2JHC ––– 13C ≈50 Hz; often leading to unexpected signs of signals in DEPT spectra and unexpected signals in 2D heteronuclear correlation spectra Coupling constants: |4JCH–C ––– CH| ≈3 Hz |5JCH–C ––– C–CH| ≈3 Hz

3340–3250 cm-1 Sharp, intensive 2260–2100 cm-1 Sometimes very week

< 210 nm (log ε 3.7–4.0)

Weak, in the case of 1-alkynes up to C7 often absent [M-1]+ often significant Extensive rearrangements, not very characteristic Isolated double bonds; for highly substituted double bonds often several weak bands m/z 45 ≈ m/z 59 m/z 31, 45, 59, … Secondary, tertiary: local maxima due to [M-33]+ α-cleavage: R . R

Rearrangements

Aromatic: [M-28]+· (CO) [M-29]+ (CHO) Aliphatic: [M-18]+· [M-46]+· Unsaturated

C H

+.

OH

-R

R

C H

+.

OH

CO and CHO elimination also from fragments. H2O elimination ([M-18]+·) only with alkyl substituent in ortho position Elimination of H2O from M+· followed by alkene elimination; elimination of H2O from products of α-cleavage Vinylcarbinols: spectra similar to those of ketones Allyl alcohols: specific aldehyde elimination: R 1

+.

OH

+.

- R 2C H O R2

R1



MS

Assignment

3.7 Oxygen Compounds Range Aromatic

63

Comments Ortho effect with appropriate substituents: O Y

H Z

+.

O Y

+.

+

H Z

with Y–Z as –CO–OR, C–hal, –O–R, and similar

UV Aliphatic Aromatic

≈200–210 nm (log ε ≈3.8) ≈270 nm (log ε ≈2.4)

No absorption above 200 nm In alkaline solution, shift to longer wavelength and increase in intensity due to deprotonation

3.7.2 Ethers

13C

1H

IR

Assignment Range al C–O 50–90 ppm al C–(C–O) 10–60 ppm al C–(C–C–O) 10–60 ppm O–C–O 85–110 ppm (C)=C–O 115–165 ppm C=(C–O) 70–120 ppm ar C–O 140–155 ppm ar C–(C–O) 100–130 ppm

Comments Oxiranes: outside the normal range Hardly any shift with respect to C–(C–CH3) Shift with respect to C–(C–C–CH3) ≈-5 ppm

CH3–O CH2–O O–CH2–O CH–O CH(O)3 H–C(O)=C H–C=C–O ar CH–C–O

Singlet

3.3–4.0 ppm 3.4–4.2 ppm 4.5–6.0 ppm 3.5–4.3 ppm ≈ 5–6 ppm 5.7–7.5 ppm 3.5–5.0 ppm 6.6–7.6 ppm

H–C(–O) st

2880–2815 cm-1

H–CH(O)2 st

2880–2750 cm-1

C–O–C st

1310–1000 cm-1

Shift with respect to (C)=C–C ≈+15 ppm Shift with respect to C=(C–C) ≈-30 ppm Shift with respect to ar C–H ≈+25 ppm Shift with respect to ar C–(C–H): ortho ≈-15 ppm meta ≈+1 ppm para ≈-8 ppm

Shift with respect to H–C(H)=C ≈+1.2 ppm Shift with respect to H–C(=C–H) ≈-1 ppm For CH3–O and CH2–O; similar range for corresponding amines Two bands Strong, sometimes two bands

64 3 Combination Tables

MS

Assignment Molecular ion Fragments

Range

Comments Aliphatic: weak, tendency to protonate Aromatic: strong Aliphatic: Base peak of aliphatic ethers generally due to m/z 31, 45, 59, … fragmentation of the bond next to the ether . + +. -R [M-33]+ bond: R C O R C O R or due to heterolytic cleavage of the C–O bond (especially for polyethers): 1

R1

Alkyl aryl ethers Diaryl ethers

1

2

O

R2

+ . - R 1 –O

2

.

R Preferential loss of the alkyl chain Preferential loss of CO (Δm 28) from M+· and/or [M-H]+ as well as: ar ar O Elimination of water or alcohol 2

+

2

1

Rearrangements

Aliphatic: [M-18]+· [M-46]+· Aromatic

Ethyl and higher alkyl ethers: alkene elimination to the phenol: +.

H O

UV

Aliphatic Aromatic



R

+.

- R C H =C H 2

OH

No absorption above 200 nm Shift to higher wavelength and increase in intensity due to the ether group



3.8 Nitrogen Compounds

65

3.8 Nitrogen Compounds 3.8.1 Amines Assignment

Range 25–70 ppm al C–(C–N) 10–60 ppm al C–(C–C–N) 10–60 ppm

13C al C–N

(C)=C–N C=(C–N) ar C–N ar C–(C–N)

1H

IR

120–170 ppm 75–125 ppm 130–150 ppm 100–130 ppm

HN–C al HN–C ar HN+–C al or ar CH3–N CH2–N CH–N CH–N+ ar CH–C–N

0.5–4.0 ppm 2.5–5.0 ppm 6.0–9.0 ppm 2.3–3.1 ppm 2.5–3.5 ppm 3.0–3.7 ppm 3.2–4.0 ppm 6.0–7.5 ppm

ar CH–C–N+

7.5–8.0 ppm

N–H st

3500–3200 cm-1

N+–H st

3000–2000 cm-1

N–H δ N+–H

δ

H–C(–N) st

1650–1550 cm-1 1600–1460 2850–2750

cm-1 cm-1

Comments Shift with respect to C–H ≈+20 ppm Shift with respect to C–(C–CH3) ≈+2 ppm Shift with respect to C–(C–C–CH3) ≈-2 ppm Shift with respect to (C)=C–C ≈+20 ppm Shift with respect to C=(C–C) ≈-25 ppm Shift with respect to C–H ≈+20 ppm Shift with respect to C–(C–H): ortho ≈-15 ppm meta ≈+1 ppm para ≈-10 ppm Often broad Singlet

Shift with respect to CH–(C–H): ortho ≈-0.8 ppm meta ≈-0.2 ppm para ≈-0.7 ppm Shift with respect to CH–(C–H): ortho ≈+0.7 ppm meta ≈+0.4 ppm para ≈+0.3 ppm

Position and shape depend on the degree of association. Often different bands for Hbonded and free NH. For NH2, always at least two bands Broad, similar to COOH but more structured Weak or absent Often weak

For CH3–N and CH2–N in amines; similar range for corresponding ethers

66 3 Combination Tables

MS

Assignment Molecular ion

Fragments

Range

Comments Odd nominal mass number for odd number of N atoms Aliphatic: weak, tendency to protonate, [M+H]+ is often important Aromatic: strong, no tendency to protonate Aliphatic: Base peak of aliphatic amines generally due m/z 30, 44, 58, … to fragmentation of the bond next to the amine bond: R1

N

CH 2

R3

+.

- R3

.

R1

CH 2

NH

CH 2

R R Elimination of alkenes following amine R cleavage: + + 2

2

Rearrangements

+

N

1

N

CH 2

R1

R No absorption above 200 nm In acidic solutions, shift to lower wavelength and decrease in intensity 2

UV Aliphatic Aromatic 3.8.2 Nitro Compounds

13C

Assignment Range al C–NO2 55–110 ppm al C–(C–NO2) 10–50 ppm al C–(C–CNO2) 10–60 ppm ar C–NO2 130–150 ppm ar C–(C–NO2) 120–140 ppm

1H

al CH–NO2 ar CH–C–NO2

IR

NO2 st as NO2 st sy Molecular ion

1660–1490 cm-1 1390–1260 cm-1

Fragments Rearrangements Aliphatic Aromatic

[M-16]+·, [M-46]+ m/z 30, [M-17]+, [M-30]+, [M-47]+· ≈275 nm (log ε