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Brooks/Cole: Pacific Grove, CA,
1998. ISBN 0 5343 5254 5. $94.95.
The publisher's advertisements tout this text as
"efficiently organized by mechanisms so students can group
and learn reactions more easily" and a text that "greatly
enhances their ability to remember reactions". These
characterizations are true with the emphasis on "remember reactions".
However, an organic chemistry course is more than just presenting a
series of reactions to be remembered. I generally think of
the introductory organic chemistry course as an interplay of
three aspects: structure, reactions, and synthesis of organic
molecules. This text uses reaction mechanisms as the organizing
principle, introduces structure where it is necessary to
support the reactions to be studied, and considers synthesis after
the mechanisms of appropriate reactions have been discussed.
As a first edition, this text is technically very good.
There are very few typographical or diagram errors, and in
general colors are used to advantage to help readers understand
diagrams and tables. Each chapter includes several tables,
diagrams, examples, and problems that should help students follow
the development of material. However, many of the tables
and diagrams are located on pages following text
discussions, making it difficult to use the diagram or table to best
advantage. The diagrams are quite well annotated and easy to
follow on their own, but the text discussions can be confusing
when the reader has to keep flipping pages to refer to the
diagram. Also, the yellow color used in the text is difficult to
see, especially in diagrams with a tan background. Use of
this color significantly reduces the effectiveness of several
tables and diagrams.
"Elaborations" that are spread throughout the text
and discuss applications of the material to relevant
medical, biological, industrial, or experimental situations are likely
to be of general interest to students. Early use of curved
arrows to interconvert resonance structures helps students
become accustomed to "thinking with arrows". The consistent use
of resonance structures throughout the text helps reinforce
the need to show resonance structures whenever
resonance arguments are invoked.
Chapter summaries generally have two elements:
an enumeration of the topics including lists of reactions, and
a list of "After completing this chapter you should be able
to:" operations. The latter list should be more useful to
students in developing an understanding of the material. In
fact, students should read each summary of operations
before reading the chapter to help them understand the
author's goals for the chapter.
Interestingly, the preface seems to address the
instructor rather than the student. It mentions students in the third
person and explains the text's approach in a way that
is understandable only to someone familiar with
alternative approaches. The tone of the preface suggests
assumptions about the abilities of readers to appreciate the logic of
the discipline. This sense of assumptions is reinforced
throughout the text.
The chapter introductions are brief and truly
informative only to those already familiar with the subject matter.
Although the organization of the text follows a logical
sequence of increasing reaction complexity in terms of the number of
steps in the reaction mechanisms and provides structural
background as needed to support discussions of reactions, the logic is
not explicitly emphasized in the introductions or discussions.
The logic may be apparent to someone familiar with
organic reaction mechanisms, but is not likely to be obvious
to students as they work their way through the material.
Thus, instructors should be sure to emphasize the logic of
the developing material.
The reaction chapters (7, 8, 10, 14-16, 18-20) all
have a similar format. The reaction and mechanism are
presented quite clearly using curved arrows, but there is
no explanation of how we know that the reaction operates by the
provided mechanism. The mechanism is then used to predict the
effects of structural changes on the rates of reactions, and finally,
a variety of examples is enumerated. Most discussions result
in the formulation of a set of rules that help predict the
outcome for a particular combination of reactants.
Sets of rules can be memorized and be helpful in
getting answers. But the text explanations of how and why
each mechanism operates are likely to be quite mysterious to
students. Although most of these explanations are understandable
to someone familiar with the material, they tend to be
uneven, and most students will need considerable assistance from
an instructor to appreciate their significance and how they
were devised. Four representative examples are provided below.
In the comparison of rates of electrophilic
aromatic substitution vs addition to alkenes (pp 838-839),
relative stabilities of both the reactants and transition states
are systematically considered to predict relative free energies
of activation. However, in the discussion of substituent effects
on SN2 reactions (pp 263-264), only steric effects are
considered and they are explained as hindrance of back-side
approach of the nucleophile, with no mention of the stabilities
of reactants or transition states. A few pages later (pp
274-275), the discussion of effects of substituents on the rates of
SN1 reactions considers only hyperconjugation effects on
the stability of the intermediate carbocation, indicating that
"Any change that makes the carbocation more stable will also
make the transition state more stable, resulting in a faster
reaction." The stability of the transition state is considered with
no mention of reactant stabilities. Later, the discussions
of inductive and resonance effects on the rate of
substitutions at the carbonyl group (p 695) include the statement
"Electron-withdrawing groups make the carbonyl carbon more
electrophilic and increase the rate", suggesting that rate can
be judged from the structure of the reactant without
considering transition state stability.
Although each explanation correctly identifies the
most important factor, the last three consider only one aspect of
the reaction. So only the first discussion considers all of
the factors that should be explored; the others do not
indicate how the specific factor discussed was selected or how
others were deemed less important. Thus, the student is likely to
be left confused when asked to analyze an unfamiliar reaction.
The discussions of IR include a large number of
nicely explained example spectra using color coordination
between structural features and spectral peaks. However, in the
explanation of IR and the absorption frequencies of
individual bonds (p 505), the Hooke's law equation is introduced
without reference to the spring model for bonds, so that it seems
to come from nowhere. The explanation of NMR is
reasonably good, with the exception of a rather confusing method
for predicting chemical shifts of protons near more than
one functional group.
Discussions of organic syntheses are likely to
overwhelm students. Chapter 9 explores simple syntheses using
SN1, SN2, E1, and E2 reactions. It is organized according to the
functional group synthesized and ends with a brief introduction
to retrosynthetic analysis. The approach of working back from
the target molecule to reasonable starting materials is
introduced; however, retro arrows are not used. The syntheses are
short, but the number of reactions is quite large and there is not
much emphasis on how to recognize potential synthetic
reactions from their products. In Chapter 16, enolate reactions
are added to the synthetic tools, the formalism of retro arrows
is established, and there are a few illustrations of
retrosynthetic analyses. Again, there is no systematic discussion of the
logic for recognizing potential synthetic steps from the
products of the step, and the number of potential reactions is
really unmanageable for students who are just learning the
process. Chapter 21 adds 13 pages of reactions (from the
summary list, pp 1021-1033), with only a short discussion of the
retroanalysis of two of the reactions.
The three synthetic chapters are excellent references
for quite specific information on a wide variety of
reactions. These chapters contain enough material for a reasonable
one-semester synthetic organic course. Consequently, just
about any desired reaction should be included, but most
instructors will need to be quite selective in choosing a subset of
the synthetic reactions for their introductory courses and
the discussion of retrosynthetic analysis will need
considerable reinforcement.
Special topics chapters include Industrial
Organic, Synthetic Polymers, Carbohydrates, Amino Acids,
Peptides and Proteins, Nucleotides and Nucleic Acids, and
Natural Products.
This text has many positive characteristics, and the
negative aspects relating to explanations are shared by most
other texts on the market. Thus, instructors who prefer
to organize their courses along mechanistic lines should give
this text careful consideration.
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