POTENTIOMETRIC DETERMINATION OF RELATIVE BASICITIES OF ALIPHATIC-AMINES IN PYRIDINE

Potentiometric titrations of methyl-, ethyl-, n-propyl-, n-butylamines and ammonia were carried out in pyridine using a standardized tetrabu tylammonium hydroxide solution. The relative basicities were found in all cases to be in the order RNH(2) > R(2)NH > R(3)N, R being an alkyl group. Basicity of any amine was assumed to be the sum of the inducti ve contribution of alkyl group(s) and a contribution from pyridine sol vent through hydrogen bonding. On this assumption, the experimental ba sicity order was rationalized. The order in pyridine is different from the order of gas phase basicities.