Application of infrared spectrometry to the study of tautomeric equilibria and hydrogen bonding basicity of medical and biochemical agents: N,N′-disubstituted amidines

Abstract

The hydrogen bonding basicity of 20 N,N′-disubstituted formamidines, acetamidines and benzamidines containing the same or different groups at the amino and imino nitrogen atoms was measured by means of the formation constant K_HB of their complexes with 4-fluorophenol in carbon tetrachloride. A method for the prediction of tautomeric equilibrium constants is proposed and was applied to unsymmetrically N,N′-disubstituted amidines. The results obtained were compared with those found on the basis of pK_a measurements in azeotropic ethanol.