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This concise book joins the series of Wiley
Interscience special topic publications. In seven chapters it selectively
reviews the burgeoning literature on organic reactions conducted
in water or in aqueous media as a reaction cosolvent,
nicely complementing another recent book on the subject by
Grieco. Following a short introduction there are six chapters that
vary in length from 10 to 50 pages; they cover pericyclic
reactions, nucleophilic additions and substitutions,
metal-mediated reactions, transition metal-catalyzed
reactions, oxidation and reduction reactions, and industrial applications. These
chapters, each of which is prefaced with a short provocative
quotation, also vary in depth, containing from 11 to more than 180
references. The literature is complete through 1996 and
commendably includes citations of original papers by Barbier,
Faraday, Frankland, Grignard, Kolbe, Lapworth, and Reformatsky as
well as references to selected U.S. and foreign patents and
the Russian literature. There is a subject index but no author index.
This book is timely and effective. From the title,
one might expect a broad discussion of the unique properties
of water and water-soluble components (salts, surfactants,
etc.) that would be thought to bear on organic reactivity. The
first chapter opens by noting that water is the most abundant
volatile material in comets and briefly describes those
properties that suggest its utility as a solvent or cosolvent,
summarizing the potential technical, economic, and environmental
advantages. Also described are the remarkable changes in density,
conductance, heat capacity, dielectric constant, and
ionization constant that accompany the transition to the critical
point, but the emphasis here is on the effect of water under
non-critical conditions. Discussion of the structure of liquid
water and the role of hydrogen bonding in mediating
molecular recognition events is abbreviated. In fact, the term
"hydrogen bond" is surprisingly absent from the index.
The text does not explicitly include a discussion of
what has come to be broadly termed biphasic reaction
conditions. Understandably, enzymatic reactions are beyond the
scope of the presentation.
This book has a decidedly applied
character with an understated environmental theme, and the
authors succinctly present the extraordinary effects of water on the
kinetics, efficiency, and stereoselectivity of a large number of
diverse reactions. In addition to their emphasis on the
historically significant aqueous Diels-Alder reaction, discovered
in 1980, and the literature regarding reactions of various
nucleophilic organometals, the authors are to be commended
for gathering together a wide and diverse body of
information: it is clear that many of the examples shown are gems
buried among larger bodies of work. Thus the book does an
excellent job of culling and surveying a vast amount of data. There
is, however, less emphasis on organizing the mechanistic
bases underlying these often dramatic effects. For example,
the apparent lack of generality of the effect of water on rate
and selectivity in pericyclic reactions calls for some
theoretical foundation. The singularly effective use of aqueous TlOH
in the Suzuki reaction is cited without comment. On the
other hand, the authors' concept of a mechanistic triad that
incorporates to various degrees anion, radical, or covalent
character in the carbon-carbon bond-forming step between
various organometals and carbonyl substrates is appealing and
suggests the need for future sophisticated experimental design.
The most interesting sections are those dealing with
synthesis and industrial applications. Unfortunately the latter
is also the shortest chapter. The synthetic examples are
timely and well chosen and include water-promoted Heck,
Stille, Suzuki, and aldol reactions. There is an extensive, highly
informative listing and survey of the use of water-soluble
phosphines (both achiral and chiral) and an excellent discussion of
the diastereoselectivity that often accompanies carbonyl attack
by indium, tin, and zinc organometals (Barbier-Grignard reaction).
The liberal use, on nearly every page, of clear,
detailed drawings enhances the text, and substantive errors are few.
Inexplicably, water is described as serving as a
presumptive weak Lewis acid (pages 54-55) in the aqueous
Mukaiyama reaction. Occasional slips of grammar, spelling, and
syntax, including confusion over the difference between media
and medium, are relatively minor. Some expressions, such
as "olefinated", are unfortunate and there are several
mysterious changes in font. This is not a textbook and no
problems are offered.
Many technical advances, some occurring since this
book was published, have impacted the economic and
environmental advantages of water. However, these more recent
findings, involving the use of triphase aqueous-fluorous-organic
systems, the discovery of living homogeneous ROMP catalysis in
water, the utilization of supercritical water oxidation for toxic
cleanup, and the utility of biphasic supercritical carbon
dioxide-water emulsions, can be appreciated within the broad
scope of reactivity described here.
With the emerging wide interest, technical feasibility,
and rapid innovative advances and an increasingly vast
literature in this area, this book is most useful as a selected
compendium rather than a definitive treatise. It is certainly suitable as
a reference in a special topics or an advanced course. Rich
with well-explicated examples and reactions, it is an
invitingly readable and valuable survey of this fascinating area.
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