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Field, L. D.
   Organic structures from 2D NMR spectra / L.D. Field, H.L. Li, and A.M. Magill.
      pages cm
   Includes bibliographical references and index.
   ISBN 978-1-118-86894-2 (pbk.)
1. Nuclear magnetic resonance spectroscopy. 2. Spectrum analysis. I. Li, H. L. (Hsiu L.) II. Magill, A. M. (Alison M.) III. Title. IV. Title: 2D NMR spectra.
   QD96.N8F54 2015
   543′.66–dc23

Obtaining structural information from spectroscopic data is an integral part of organic chemistry courses at all universities. At this time, NMR spectroscopy is arguably the most powerful of the spectroscopic techniques for elucidating the structure of unknown organic compounds, and the method continues to evolve over time.

This text Organic Structures from 2D NMR Spectra builds on the popular series Organic Structures from Spectra, which is now in its fifth edition. The aim of Organic Structures from Spectra is to teach students to solve simple structural problems efficiently by using combinations of the major spectroscopic and analytical techniques (UV, IR, NMR and mass spectroscopy). Probably the most significant advances in recent years have been in the routine availability of quite advanced 2D NMR techniques. This text deals specifically with the use of more advanced 2D NMR techniques, which have now become routine and almost automatic in almost all NMR laboratories.

In this book, we continue the basic philosophy that learning how to identify organic structures from spectroscopic data is best done by working through examples. Solving real problems as puzzles is also addictive – there is a real sense of achievement, understanding and satisfaction. About 70% of the book is dedicated to a series of more than 60 graded examples ranging from very elementary problems (designed to demonstrate useful problem-solving techniques) through to very challenging problems at the end of the collection.

The underlying theory has been kept to a minimum, and the theory contained in this book is only sufficient to gain a basic understanding of the techniques actually used in solving the problems. We refer readers to other sources for a more detailed description of both the theory of NMR spectroscopy and the principles underpinning the NMR experiments now in common use.

The following books are useful sources for additional detail on the theory and practice of NMR spectroscopy:

(i) T. D. W. Claridge, High-Resolution NMR Techniques in Organic Chemistry, 2nd edition, Elsevier, Amsterdam, 2009. ISBN 978-0-08-054628-5.

(ii) J. Keeler, Understanding NMR Spectroscopy, 2nd edition, John Wiley & Sons, UK, 2010. ISBN 978-0-470-74609-7.

(iii) H. Friebolin, Basic One- and Two-Dimensional NMR Spectroscopy, 5th edition, Wiley-VCH, Weinheim, 2011. ISBN 978-3-527-32782-9.

(iv) H. Günther, NMR Spectroscopy: Basic Principles, Concepts and Applications in Chemistry, 3rd edition, Wiley-VCH, Weinheim, 2013. ISBN 978-3-527-33000-3.

In this book, the need to learn data has been kept to a minimum. It is more important to become conversant with the important spectroscopic techniques and the general characteristics of different types of organic compounds than to have an encyclopaedic knowledge of more extensive sets of data. The text does contain sufficient data to solve the problems, and again there are other excellent sources of data for NMR spectroscopy.

The following collections are useful sources of spectroscopic data on organic compounds:

(i) http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/cre_index.cgi?lang=eng, maintained by the National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan.

(ii) http://webbook.nist.gov/chemistry/, which is the NIST Chemistry WebBook, NIST Standard Reference Database Number 69, June 2005, Eds. P. J. Linstrom and W. G. Mallard.

(iii) E. Pretch, P. Bühlmann and M. Badertscher, Structure Determination of Organic Compounds, Tables of Spectral Data, Springer-Verlag, Berlin/Heidelberg, 2009. ISBN 978-3-540-93810-1.

ASSUMED KNOWLEDGE

The book assumes that students have completed an elementary organic chemistry course, so there is a basic understanding of structural organic chemistry, functional groups, aromatic and non-aromatic compounds, stereochemistry, etc. It is also assumed that students already have a working knowledge of how various spectroscopic techniques (UV, IR, NMR and mass spectroscopy) are used to elucidate the structures of organic compounds.

The following books are useful texts dealing with the elucidation of the structures of organic compounds by spectroscopy:

(i) L. D. Field, S. Sternhell and J. R. Kalman, Organic Structures from Spectra, 5th edition, John Wiley & Sons, UK, 2013. ISBN 978-1-118-32545-2.

(ii) R. M. Silverstein, F. X. Webster, D. J. Kiemle and D. L. Bryce, Spectrometric Identification of Organic Compounds, 8th edition, John Wiley & Sons, USA, 2014. ISBN 978-0-470-61637-6.

STRUCTURE OF THE BOOK

INSTRUMENTATION

The NMR spectra presented in the problems contained in this book were obtained under conditions stated on the individual problem sheets. Spectra were obtained on the following instruments:

(i) 300 MHz ¹H NMR spectra, 75 MHz ¹³C NMR spectra and 283 MHz ¹⁹F spectra on a Bruker DPX-300 spectrometer;

(ii) 400 MHz ¹H NMR spectra, 100 MHz ¹³C NMR spectra and 376 MHz ¹⁹F spectra on Bruker Avance III 400 spectrometers;

(iii) 500 MHz ¹H NMR and 125 MHz ¹³C NMR spectra on a Bruker Avance III 500 spectrometer;

(iv) 600 MHz ¹H NMR and 150 MHz ¹³C NMR spectra were obtained on Avance III 600 or Avance III HD 600 Cryoprobe spectrometers.

There is a companion Instructor’s Guide which provides a comprehensive step-by-step solution to every problem in the book.

Bona fide instructors may obtain a list of solutions (at no charge) by emailing the authors at L.Field@unsw.edu.au or fax (+61 2 9385 8008).

We wish to thank Dr Donald Thomas and Dr James Hook at the Mark Wainwright Analytical Centre at the University of New South Wales, and Dr Joanna Cosgriff and Dr Roger Mulder at CSIRO Materials Science and Engineering who helped to assemble the additional samples and spectra used in this book. Thanks are also due to Dr Samantha Furfari and Dr Manohari Abeysinghe who helped with the synthesis of several of the compounds used in the problems.

2.1 ¹H NMR spectra (a) time domain spectrum (FID); (b) frequency domain spectrum obtained after Fourier Transformation of (a).

2.3 ¹H NMR spectrum of bromoethane (simulated at 90 MHz, CDCl₃) showing the multiplicity of the two ¹H signals.

2.4 ¹H NMR spectrum of 1,2,4-trichlorobenzene (500 MHz, CDCl₃) showing the multiplicity of the three ¹H signals.

2.5 The dependence of vicinal coupling constants (³J_HH, Hz) on dihedral angle (φ) (Karplus relationship).