NMR spectra of pyrimidines. Effect of substituents on the chemical shift of the protons of the amino group of p-substituted 2- and 5-aminopyridines and anilines

Abstract

The chemical shifts of the protons of the amino groups of p-substituted anilines and 2- and 5-aminopyrimidines in dimethyl sulfoxide were measured, and their dependence on the inductive and conjugative constants of the substituents was studied. On the basis of an analysis of the correlation equations it was concluded that there is a rather close similarity in the pyrimidine and benzene rings with respect to their conductivity of the inductive effect of substituents in the para position. A difference in the conductivity of the electronic effects of substituents over the system of π bonds of the pyrimidine ring as a function of the relative orientation of the substituents and the reaction center is demonstrated.