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Über dieses Buch

For several years we have been organizing seminars and workshops on the application of modem one­ and two-dimensional NMR methods at the faculty of chemistry in the Ruhr-University Bochum, FRG, and elsewhere, addressing researchers and graduate students who work in the field of organic and natural products chemistry. In 1987, we wrote a workbook (StrukturaufkUirung mit modemer NMR-Spektroskopie, Steinkopff, Darmstadt, FRG, 1988) in German language based on our experience in these courses. Many of the exercises described therein have been used in such courses and some of them have been shaped by the participants to a great extent. The response of readers and discussions with colleagues from many countries encouraged us to produce an English translation in order to make the book accessible to a wider audience. Moreover, the content has been increased from 20 exercise examples in the German, to 23 in the English version. This book could not have been written in the present form without the help of a number of col­ leagues and, therefore, we acknowledge gratefully the generous supply of samples from and useful discussions with B. Abegaz (Addis Ababa, Ethiopia), U.H. Brinker (Bingham, New York, USA), E.

Inhaltsverzeichnis

Frontmatter

1. Introduction

Abstract
Since the early 1980s modern NMR spectroscopy — especially the two-dimensional methodology — has become an extraordinarily useful tool in the structural elucidation of unknown organic compounds. Nowadays, the latest generation spectrometers with their increasingly powerful pulse programmers, computers, and data storage devices, enable the user to perform routinely many multipulse experiments with a time expenditure no longer significantly exceeding that of most traditional techniques, as for instance, multiple selective decoupling. On the other hand, much more information can be extracted from multipulse than from conventional measurements.
H. Duddeck, W. Dietrich

2. Methodology

Abstract
In the following sections the basic multipulse NMR techniques used in the exercises are introduced. The emphasis, however, is not on the physical description and explanation of the pulse sequences, but on the practical evaluation of the spectra and their importance in structural elucidation.
H. Duddeck, W. Dietrich

3. Exercises

Abstract
Many of the exercises in this book contain additional information about aggregate states, characterisstic IR bands, molecular formulas obtainable from high-resolution mass spectra, and so forth. Often the constitution formula is given, and sometimes statements about the configuration are offered. This closely follows actual practice, since prior to taking an NMR measurement it is normal laboratory procedure to have on hand the chemical history of the compound and information derived from other spectroscopic methods.
H. Duddeck, W. Dietrich

4. Strategies

Abstract
The NMR spectra, especially the 2D spectra discussed in Chapter 3, contain a wealth of information. It is important, therefore, to be certain of the relative value of each single piece of information. There are “soft” clues or hints that can only be evaluated through experience and a knowledge of analogous findings, that is, on the basis of empirical evidence. A typical example is the evaluation of the chemical shift (δ) of an atom by taking into account the nature of its neighboring atoms. Such hints should, whenever possible, be verified by experimental results. Information from characteristic δ ranges are more reliable. For instance, is clear that a 13C signal with δ = 210 corresponds to a carbonyl carbon and that this carbon cannot be a member of a carboxyl function. Many 1H,1H and 13C,13C coupling constants belong to the same category of reliable hints.
H. Duddeck, W. Dietrich

5. Solutions

Abstract
In this chapter we suggest explicit procedures for solving the problems in the 23 exercises. It is again emphasized that the proposed solutions are by no means the only ones possible. Others may be better and more elegant.
H. Duddeck, W. Dietrich

Backmatter

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