Steric Effects on the Base Strengths of Cyclic Amines

Abstract

A series of 1- and 2-methyl derivatives of piperidine exhibiting a wide variation in degree of steric hindrance was prepared. Their base strengths in water and in acetonitrile wrere measured. Those of the tertiary amines rose markedly as the degree of substitution increased, but those of the secondary amines rose only slightly. Our interpretation is that the methyl groups interfere with hydration of the secondary ammonium ions, thus offsetting the polar effects of the former. © 1957, American Chemical Society. All rights reserved.