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Yet another sophomore organic lab manual, you ask? Why on earth should this
be? It is difficult to offer a unique product in such a well-established market.
With the increasing popularity of desktop publishing, more and more lab instructors
choose to write their own manuals rather than be constrained by commercially available
products. There is also a traditional set of lab techniques and experiments which
has for decades remained mostly unchanged, so why re-invent the wheel? Well, those
who do not wish to go to the trouble of writing their own manual will be pleased
to discover that Hill and Barbaro offer some alternatives to other manuals you
may have seen.
For the traditionally inclined, all the common separation techniques are included,
and the selection is unremarkable. Syntheses for cyclohexene, diphenylacetylene,
Grignard and Diels-Alder reactions, the venerable benzaldehyde/acetone crossed
aldol, the Fisher esterification, and synthesis of aspirin are provided. For variety,
some syntheses offer a choice of targets; four different amides can be made, and
four different aromatics can be nitrated.
But there are some innovations that should not be overlooked. A notable inclusion
is a dozen syntheses labeled "mystery reactions." In these experiments, students
are not informed of the identity of their product. They are told that the product
is one of 4–10 possibilities listed in a table, and that they are required
to find out its identity by methods ranging from simple melting point to derivatization
to IR or NMR analysis. Two of the mystery reactions are the Hofmann rearrangement
and the Cannizzaro reaction. Similarly, students are not told in advance but are
required to determine which product isomer predominates in each of the nitrations
mentioned earlier. Organic qualitative analysis (QA) is a subtle presence in the
book. Instead of there being a single QA section involving extended work over
several weeks, some individual procedures appear as components of different experiments.
The Diels–Alder reaction includes a microwave option that appeared in
this Journal (1). The synthesis of glucose pentaacetate
is followed by an NMR experiment using J values to determine which anomer is the
major product; oddly, the authors omit any discussion of the anomeric effect so
common in carbohydrates and derivatives, so students may not understand why the
more stable conformation of a compound could contain two adjacent diaxial groups.
This book has other positive features. Descriptions of basic techniques are
clear, concise, and readable. Figures are included, none are very complex, and
many are well annotated. The discussion of theoretical yield is exemplary. Directions
for most synthesis experiments are also clear and detailed—both macro and
microscale procedures are provided in most cases. In several places the authors
deftly help students avoid common pitfalls; for example, students are directed
to add cyclohexene to a bromine solution so they don't miss the decolorization.
Students get multiple reminders to avoid common traps such as discarding layers
after performing solvent extractions. Safety instructions are clear, frequent,
and adequately detailed. Explicit, detailed directions are given on pooling of
organic waste for proper disposal. An instructors' manual is available upon adoption
of the text.
Pagination is done by a unique system. The book is divided into sections with
general information (G), lab techniques (T), ordinary experiments (E), and mystery
experiments (M). Each page starts with a letter, then a hyphenated number. For
example, E 6-3 is the third page of experiment six.
No text is without its shortcomings, but there aren't many mistakes. The authors
assert that "The mole percentage composition of a mixture can be obtained directlyÉby
comparing GC peak areas of the various componentsÉ" This is true only for FID
detectors, and even then some compounds can be exceptions. The authors make no
mention of relative response factors, which are needed for TCD, ECD, and even
some MS detectors. On page T 7-2, normal phase TLC is described adequately but
the subsequent discussion of what is apparently reverse-phase (RP) TLC lacks any
mention of a difference in the stationary phase. On the next page, Figure 2 is
evidently a RP plate, but RP chromatography is not discussed until page T 8-5
(GC separations). On page E 6-3, a figure shows a reflux setup with water running
through the condenser as usual, which contradicts directions to not run water
through the condenser. There are no suggested time allotments for experimental
procedures, either in the manual or in the instructor's book.
A lab instructor may have a different point of view from the authors. For most
syntheses, the physical constants are given for the substances involved; no effort
is made to encourage students to look up this data in handbooks; they can simply
transcribe the tables. On page T 5-3 where solvent extraction is discussed, the
value given for an example of KD is too high to convince students that multiple
extractions with smaller batches of solvent are more effective than single extractions.
Despite concerns about the carcinogenicity of CH2Cl2 expressed
in experiment 4A (where ethyl acetate is substituted), CH2Cl2
is used without comment in a number of subsequent experiments.
Overall, this lab manual is worth earnest consideration. If its features aren't
sufficiently attractive, one can just get busy and write one's own manual…
Literature Cited
1. Bari, S. S.; Bose, A. K.; Chaudhary, A. G.; Manhas, M.
S.; Raju, V. S.; Robb, E. W. J. Chem. Educ. 1992, 69, 938.
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