Amines introduces the first of the nitrogen-containing groups.
In this unit structure, nomenclature, physical properties, preparations,
reactions, and both chemical and spectroscopic analysis are included.
The relationship between the familiar structure of ammonia and the
subsequent structure of amines provides an introduction to both
the structure and the classification of amines. The naming of amines
includes the common names as well as the systematic (IUPAC) names
students should know. Aromatic names are included.
The section on physical properties of amines addresses the usual
properties of boiling points and solubilities with emphasis on the
ability or inability to form hydrogen bonds. The sharp difference
in the boiling points of first, second, and third degree amines
having the same molecular weights are explained, as are the differences
in water solubility. The solubility increase resulting from salt
formation is treated as a way of making aqueous solutions of otherwise
insoluble amines. Structural features impacting Lewis basicity are
discussed and explained. The basicity of aqueous solutions is addressed
by using equilibrium problems involving Kb as a means of stressing
the distinctly basic nature of these solutions.
Reduction reactions, substitution reactions, the Gabriel Synthesis,
the Hofmann rearrangement and reduction of azides are treated in
the section on preparation of amines. Reductive amination involving
Schiff's bases is only one of the reduction methods described.
Reduction of nitros, amides, and nitriles is also included. The
mechanism for the SN2 reaction of phthalimide with alkyl halides
(the Gabriel Synthesis) is shown. It is strongly advised that the
student have completed the unit on substitution vs. elimination
reactions prior to undertaking the study of amines. The intricacies
of the Hofmann rearrangement of amides is discussed in detail. The
reduction of azides is treated so that the student understands the
many possibilities which arise from thinking of this reaction when
The reactions of amines addressed include the Hinsberg, electrophilic
aromatic substitution, nitrosation, and the Hofmann elimination.
The Hinsberg is carefully developed as an appropriate test tube
test to determine the degree of amine encountered. Electrophilic
aromatic substitution recalls the activating nature of the aromatic
amine. The formation of diazzonium salts as an intermediate pathway
for the formation of numerous other types of compounds is addressed.
The problems encountered when second degree amines are treated to
nitrosation is addressed with the view that organic students must
be aware of the dangers of many of the compounds with which they
work. The E2 mechanism for Hofmann elimination using quaternaries
The unit on amines concludes with discussion of chemical analysis.
Not only is chemical analysis discussed, but the spectral analyses
using IR, NMR, and CMR with amines is covered.