Distinguishing Amines

Three isomeric (C7H15N) liquid amines are found in separate bottles with no labels. We shall refer to these unknowns as A, B & C. These amines are known to be aminocycloheptane, 4,4-dimethylpiperidine & dimethylaminocyclopentane (structures shown to the right). Each of these compounds is slightly soluble in water (ca. 4%), and each dissolves completely in 10% aqueous HCl.
To discover which is which, two chemical tests may be applied to these unknowns:

1. Treatment with cold nitrous acid (HONO).
2. (i) Treatment with benzenesulfonyl chloride (C6H5SO2Cl) in KOH solution.
    (ii) Acidification of the mixture obtained from (i).

Isomer Treatment
with HONO
in KOH
of resulting mixture


Once you have conducted your tests, make structural assignments to A, B & C in the boxes following the compound names.

Aminocycloheptane   ............. 
4,4-Dimethylpiperidine ............
Dimethylaminocyclopentane ..

This script written by William Reusch, Dept. of Chemistry, Michigan State University. Please send comments and corrections to whreusch@pilot.msu.edu.