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Book Review Energetics of Organic Free Radicals. (Series Search Vol. 4). Edited by J. A. M. Simes A. Greenberg and J. F

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The fifth and longcst chapter in the
book is titled “Supramolecular Inorganic
Chemistry.” In spitc of this cxciting title,
I found this to be the low point of thc
book. It was difficult to read, and filled
with verbose and lengthy discussions on
terminology and scniantics. I found thc
conccpts that were introduced, such as
“domains of molecules,” to be of no value. The illustrations were dreadful and the
organization was hard to follow. Several
scctions had littlc to d o with crystalline
systcms. It is unfortunatc that this chapter
consumes one-third of the entirc book.
Chapter 6 was an interesting and informative description of thc (beta-alpha)8
bar]-el protein architecture. The author
worked from the basics to build a wonderful picture of the marvels of protein sclfassembly and self-organization. Even
though the subject did not fit pcrfectly into the main t h e m of crystals as supramolecular entitics, therc are many valuable lessons to be lcarned from these
biomolecular systems that could be applied to more traditional molecular solid
state chemistry. The chaptcr was well
writtcn and easy to understand, even for a
non-specialist in this area.
On the whole, the book is consistent
with the philosophy of thc “Perspectives”
series conccntrating on goal-oriented
supramolccular chemistry. Although I
would not call this a treasure-trove of
crystalline suprainolceular chemistry,
thcre are a fcw contributions which may
be worthwhile to thosc with an intcrcst in
the field.
Jeffic~yS. h.1oorc
Dcpartments of Chemistry and
Materials Science and Engineering
Roger Adams Laboratory
University of Illinois
Urbana, IL (USA)
Energetics of Organic Free Radicals.
(Series: Search, Vol. 4). Edited by
J A . M . Simcies, A . Greenberg and
J F: Liehmun. Chapman and Hall,
L o n d o n , 1996. 301 pp., hardcover
E 39.95.-ISBN 0-7514-0378-4
I have often wished, while working with
an intercsting textbook or monograph,
that it had been availablc to me some
years carlicr, for cxamplc in my time as a
final year degree student or during postgraduate study. In that way I might have
gained a deeper insight into some of the
topics studicd. espccially if, for example,
the concepts of thcrmochcmistry and the
rcactivc propertics of frec radicals had
been explained so clearly as thcy are in
this fourth volumc of the Seurcli series. In
this book thc editors havc set out to
provide a broadly based introduction to
the structurcs, enei-gctics, and reactivities
of free radicals, by including multidisciplinary contributions from a number of
recognized expcrts.
Frcc radical rcactions occur much more
commonly in thc biosphere and atmosphere around us than onc might at first
suppose in view of the short-lived nature
of these intermediates. Chevcs Walling,
author of the article “Frcc Radical Reactions”, has several decades of expcrience
in this ficld of research. He bcgins with thc
basic principlcs of free radical chemistry,
and cxplains thc meanings of thc various
thermochemical quantitics involved. The
concept of an elemcntary reaction is then
dcfined, with appropriate examples, and
on this basis some important rcaction
mechanisms are identified. This approach
enables thc reader to gain a sound undcrstanding of encrgy barriers and thc factors
that contribute to thcm, and of the rate
constants for some important processes.
Since reactions involving free radicals
mostly take place under neutral conditions, thc thermochemistry of the educts,
intermediates, and products is of great importance for predicting thc behavior of
proccsses with applications in synthesis.
The various mcthods for determining
standard enthalpies of formation, for example from kinetic measurements, from
calculations based on thermodynamic
cyclic processes, o r cvcn directly from
mass-spectronietric data, arc describcd
hcrc in two articles, by Wing Tsang and by
John C. Traeger and Barbara M. Kompe.
But how does onc obtain meaningful values for heats of formation in systems for
which it is difficuit to sct up precise expcrimcnts. such as those involving ethynyl,
vinyl or chloroxyl radicals? In fact, for
many such systems theoretical methods
have been developcd to such an cxtent
that, after first carefully cvaluating the
available methods and choosing the one
best suited to the problem, it is possible to
calculate thc required thermodynamic
quantities with reasonable accuracy. In
some cases this gives vcry good results indeed, as exemplificd in thc article “Theoretical Studies of the Energetics of Radicals”, by Joseph S. Francisco and John A.
Montomery, Jr. One method for the direct
mcasuremcnt of reaction enthalpies in solution is photoacoustic calorimetry, described in the article by Joshua L. Goodman, with examples of applications to
photochemical reactions and to the reactions of 1,2- or 1,3-biradicals. The data
thus obtained can be used to cstimate thc
behavior of allowed or forbidden processes. By applying such Considerations to
free radical 1,2-rcarrangcincnts, which arc
common in thc chemistry ofcarbocations,
it has becn shown that thcrc is a high cncrgy barrier to such processes if a paramagnetic intermediate is involved. However,
in the articlc “Resonance and 1,2-Rearrangement Enthalpies in Radicals: From
Alkyl Radicals to Alkylcobalamins”,
Arthur Grccnberg and Joel F. Liebinan
describe how the lattcr reactions can be
carried o u t remarkably easily with the
help of the coenzymc B I Z . Against this
background onc can well understand why
the editors have included in this book on
free radicals the articlc “A Short and 11lustrated Guide to Mctal-Alkyl Bonding
Energetics”, by J. A. Martinho SoniBcs
and M. E. Minas D a Piedadc. This article
and the last one, which deals with a topic
that will undoubtedly remain vcry important in the future: “Solvent Effects of
Neutral Frec Radicals”, by James M.
Tanko and N. Kamrudin Sulenian, are the
two inost impressive in the book.
The book is intended mainly for advanced and postgraduate students whose
particular interests include organic and
physical Chemistry. It offers a thoroughly
up-to-date trcatmcnt of the methods, with
many refercnces to the relevant litcrature.
The introductory sections on basic concepts are seldom longer than necessary,
while adequate space is devoted to dcscribing the mcthods and critically cvaluating the extensive (and sometimes contradictory) literature data on the
thermodynamics of frce radical reactions.
Such an evaluation is an important aid for
anyonc involved in mechanistic studies or
synthetic work using free radicals. The
tables of thcrniochemical data and the dcscriptions of the methods used to determine them will cnablc the reader to quickly gain an appreciation of the factors
affecting thc quality of such data.
Jens Hurtzing
Institut fur Organischc Chemie
dcr Universitiit Wiirzburg (Germany)
The Chemistry of Free Radical Polymerization. By G. Moad and D . H .
Solomon. Pergamon/EIsevier, Oxford, 1995. 408 pp., hardcover
E 75.00. - ISBN 0-08-42078-8
Interest in free radical polymcrization
has increased greatly in the last fcw years.
This is due mainly to a combination of
two factors. Firstly, thc conventional thcories d o not give a coinplctely satisfactory
description of free radical polymerization; in particular, thcy d o not cnable one
to predict the dcpendcnce of the polymer-
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