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Book Review Solving Problems with NMR Spectroscopy. By A.-u. Rahman and M. I. Choudhary

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BOOKS
and phase cycle, the spectrometer settings
and conditions appropriate for a specific
sample solution, the processing of the
recorded data, typical results including an
actual spectrum (reproduced in excellent
quality), and additional information
about the method. Each subchapter is
self-contained, so that the reader can concentrate on the method in hand without
needing to have read the previous sections.
The first five chapters are concerned
with basic spectrometer procedures such
as tuning the probe-head, optimizing the
magnetic field homogeneity, determining
the pulse length, and carrying out simple
NMR experiments, including recording
‘H and 13Cspectra under standard conditions, decoupling techniques, and dynamic NMR measurements. In Chapter 6 the
reader learns about multiplicity selection
methods (spectral “editing”), including
the APT, INEPT, and DEPT techniques,
about pulse sequences used as building
blocks in more complicated sequences
(the BIRD filter, etc.), and about methods
for suppressing the water signal. Chapter
7 is devoted to experiments using selective
pulses, and Chapter 8 to the use of auxiliary reagents and to quantitative measurements. Chapter 9 introduces heteronuclear NMR spectroscopy. The topics of
the last three chapters are two-dimensional methods (including H,H shift correlations, C,H correlation methods using
either 13C or ‘H detection, and others),
NMR experiments with pulsed field gradients, and 3D NMR experiments. The
book ends with two appendices, the first
listing the different names used by various
instrument manufacturers to describe the
recording parameters, and the second explaining the basic rules of the product operator formalism.
The authors have included here the
most important and frequently used
NMR methods, and their choice of experiments is appropriate for the intended
readership. However, in the chapter on
heteronuclear NMR spectroscopy we
would have expected to find examples of
measurements on 31P, certainly a much
more important nuclide than “B and
1 7 0 , which are chosen here. Chapters 6
(“ID Multipulse Sequences”) and 10
(“The Second Dimension”) are especially
well constructed from a teaching standpoint. All the experiments described in the
book use only compounds that are readily
available. In the 3D H,C,P correlation experiment the potential applications of the
technique could have been demonstrated
more convincingly by choosing, instead of
triphenylphosphine, a compound having
more than one chemical shift value in each
2266
dimension.
The methods are described in a clearly
understandable way which should enable
readers to perform the experiments without serious problems. However, those
with little practical experience of NMR
spectrometers may have a few difficulties
with processing the data, especially if they
are using a spectrometer of a different
make from that of the authors, this despite the translations of technical terms in
the appendix. Also, readers with less theoretical background would be better able
to understand the pulse sequences if these
were explained using the magnetization
vector picture wherever possible, rather
than the product operator formalism.
This book dealing with the practical aspects of carrying out NMR experiments
fills a gap between the operating manuals
provided by instrument manufacturers
and the mainly theoretically-orientated
books on the subject. It can be thoroughly
recommended for purchasing by every
NMR laboratory.
Kerstin Ibrom
Konigstein im Taunus
Ludger Ernst
NMR-Laboratorium
der Chemischen Institute
der Technischen-Universitat
Braunschweig
Braunschweig (Germany)
Solving Problems with NMR Spectroscopy. By A.-u. Rahman and M . I.
Choudhary. Academic Press, San
Diego, 1996. xvi, 430 pp., paperback
$34.95.-ISBN 0-12-066320-1
The purpose of this book, according to
the authors, is to provide research
chemists with the practical knowledge
needed to use NMR methods for determining the structures of organic molecules. They have been especially concerned to avoid making it too techiiical.
and wherever possible they have de. ribetl
the underlying principles of the qeri
ments in non-mathematical lansuage
Like the book by Braun et al. which is
reviewed above, it is concerned with the
practical details of carrying out NMR experiments, but here there is more emphasis on analyzing the results.
The book begins with a long chapter
(98 pp.) on the fundamentals of modern
NMR spectroscopy. Aspects covered include the most important parts of the
spectrometer, basic operations with the
instrument, the effects of radiofrequency
pulses on the magnetization vector, pro-
Q VCH Verlrigsgesel[srhafi mbH, 0-69451 Weinhetm, 1996
cessing of the experimental data, and
technical points related to these. Chapter
2 (57 pp.) is concerned with spin-echo and
polarization transfer methods, with particular attention to the APT, INEPT, and
DEPT techniques. Chapter 3 (37 pp.) introduces the basic principles of two-dimensional NMR spectroscopy, explaining how the data are recorded and
subsequently processed, but not yet going
so far as to describe specific experiments.
In Chapter 4 (25 pp.) the authors discuss
the nuclear Overhauser effect (NOE) and
the practical aspects of recording NOE
difference spectra. The real core of the
book is Chapter 5 (131 pp.), which is
devoted to various important 2D NMR
experiments. These include the recording
of homonuclear and heteronuclear Jresolved spectra, homonuclear and heteronuclear chemical shift correlation experiments, 2D nuclear Overhauser experiments (NOESY, ROESY, HOESY) and
exchange spectroscopy (EXSY), the 2D
TOCSY and INADEQUATE experiments, and heteronuclear correlation experiments with proton detection (HMQC,
HMBC). Chapter 6 (19 pp.) introduces
the principles of 3D NMR spectroscopy
and describes a few of the many types of
experiments that are possible. Chapter 7
(26 pp.), on recent developments in NMR
spectroscopy, is mainly concerned with
experiments using frequency-selective
excitation pulses, with a brief mention of
the use of pulsed field gradients for suppressing unwanted coherences. Lastly,
Chapter 8 (19 pp.) considers how one
should approach the problem of determining an unknown molecular structure,
giving general recommendations as to
which experiments should be performed
and in what order, together with the analysis of the results. The authors then describe the sequence of events in a structural analysis, using two examples from
their own research, a lupinine alkaloid
and a steroid alkaloid. The book ends
with a glossary of technical terms used in
NMR spectroscopy (10 pp.) and a subject
index of similar length.
The text is in general easy to read and
understand, and gives good explanations
of the most important NMR techniques in
current use. However, it is not completely
clear which readers the book is intended
for. Beginners without any previous
knowledge will find that many of the descriptions are not sufficiently detailed,
whereas for experienced NMR users
much of the information is superfluous.
The book does not fully live u p to the
promise of its title. To solve structural
problems without any previous knowledge of chemical shifts and coupling con-
0570-0833196l3S19-2266 S 1S.OOi .2S/O
Angew. Chem. h i . Ed. Engl. 1996.35. No. 19
BOOKS
stants, neither of which is discussed in the
book, may often be possible in principle,
but is usually not the most efficient approach. Also some important older and
well-established techniques, such as spin
decoupling, are not discussed. A more
honest title for the book would be something like “Modern N M R Spectroscopic
Techniques” .
The inclusion of exercise problems with
answers in each chapter is a welcome feature. Unfortunately, however, the questions posed are not always very useful
from a learning standpoint (example:
“The signal-to-noise ratio can be increased by [applying] proper apodization
functions. What would happen without
apodization?”), and occasionally they
suggest a whimsical attitude on the part of
the authors. For example, to the question
of what type of probe-head is most suitable for a group of preparative chemists
where the problem of insufficient sample
does not arise. the answer given is “a
probe-head for 10-15 mm sample tubes”.
The book’s most serious shortcoming is
that many of the figures are of very poor
quality. This applies especially to the reproduction of spectra, a few of which have
obviously been drawn by hand. Many of
the 2D spectra are much too small. Occasionally the one-dimensional spectrum is
missing from one of the axes, or is shown
on such a small scale that only methyl
group singlets are adequately reproduced
(4 mm height!), with the result that no
coupling multiplets can be recognized,
since they would only be a fraction of a
millimeter in height. This happens even on
pages whose space is not fully used. The
book would have been much improved by
using a larger format and taking greater
care with the layout. It needs to be thoroughly reworked.
Ludger Ernst
NMR-Laboratorium
der Chemischen Institute
der Technischen Universitat
Braunschweig
Braunschweig (Germany)
Kerstin Ibrom
Konigstein im Taunus (Germany)
Angew Chem. Ii i l Ed Engl. 19%. 35, N o 19
Unimolecular Reactions. Second edition. By K. A . Holbrook, M . J. Pilling
and S. H. Robertson. Wiley, ChiChester, 1996. 417 pp., hardcover
.€ 90.00.-ISBN 0-471-92268-4
The subject of unimolecular reactions
has undergone much development in the
last few decades. Many new types of experiments have been carried out, affording insights that could scarcely have been
imagined 30 years ago. It has become possible to make remarkably precise measurements on reactions of practical importance. Alongside these advances,
theoretical methods now allow one to analyze the fundamental processes with improving quantitative reliability. Consequently, monographs and review articles
dealing with this fast-moving field soon
become outdated. It is therefore very
pleasing that K. A. Holbrook, M.J.
Pilling, and S. H. Robertson have now
produced a thoroughly revised and significantly enlarged new edition of Unimolecular Reactions, first published in 1972 under the authorship of P. J. Robinson and
K. A. Holbrook. In that first edition,
“Robinson and Holbrook” contained an
excellent introduction to the application
of the H R R K M theory, the statistical
theory of unimolecular reactions developed by Hinshelwood, Rice, Ramsperger,
Kassel, and Marcus, together with a
detailed compilation of experimental
data on classical reactions. At that time
this was the most detailed introduction to the practical application of the
R R K M theory available in the literature. However, in recent years it had become seriously outdated because the
many later developments were not covered.
Thermal and nonthermal unimolecular
reactions are often studied under conditions in which the reaction rate is determined solely o r partly by intermolecular
energy exchange through collisions. In
retrospect it seems surprising that for
many years the details of this process received so little attention. The new edition
of this book remedies that omission by
including descriptions based on the fundamental equations. Nevertheless, perhaps an even more detailed treatment of
the energy transfer process would have
conveyed a better understanding of its
characteristics.
The new numerical algorithms for calculating densities of states and numbers of
states are treated in detail in this book,
so that the statistical analyses of the
R R K M theory can be carried to completion. Thus, even a beginner should have
no difficulty in learning how to treat reac-
0 VCH Verlugsgesellschuft mhH. 0.69451
Wemherm. 1996
tions involving rigid activated complexes,
for which the classical R R K M theory was
mainly developed. The new edition also
includes a detailed treatment of reactions
involving nonrigid activated complexes.
The description and comparison of the
different variants of theoretical treatments of the transition state is excellent
and useful. In view of this it is even more
surprising that the phase space theory,
which represents the limiting case of completely flexible transition states, and
makes it easy to correctly take into account the conservation of angular momentum in the reaction, is almost completely ignored. To have included a
treatment of this limiting case would have
helped the reader to understand the detailed description of the statistical adiabatic channel model.
The book contains a wealth of information about current experimental and theoretical studies in this field. The descriptions of the kinds of investigations now
possible are illustrated by informative examples, thus providing the beginner with
an excellent introduction and the more
advanced researcher with many stimulating ideas. It retains the spirit of the original “Robinson and Holbrook”, while also
bringing the treatment up to date. If the
book had been completely rewritten from
the start, there would probably have been
some changes of emphasis. It would then
have been possible to devote more space
to topics such as the breakdown of molecular ions, bimolecular complex-forming
reactions of neutral or charged species,
trajectory calculations, calculations of
adiabatic channel potentials made possible by the latest methods, anharmonic
densities of states, and (as already mentioned above) phase space theory. At the
same time the treatment of the classical
R R K M theory could be shortened. However, to do so would have resulted in a
more bulky monograph than intended.
Therefore the changes have been limited
to a very successful updating of the original concept. The book is well suited as a
text for further reading by advanced students, and will also serve the needs of reaction kineticists who intend to work on
gas phase reactions.
Jurgen Troe
Institut fur Physikalische Chemie
der Universitat Gottingen (Germany)
0570-0833196/35I9-2267 $15.00+ .25/0
2267
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