Potentiometric investigations of molecular heteroconjugation equilibria of substituted phenol + n-butylamine systems in dimethyl sulfoxide

Abstract

Molecular heteroconjugation constants, K BHA DMSO and K AHB DMSO , expressed as their logarithms, have been determined by potentiometric titration for eleven substituted phenol + n-butylamine systems in a polar protophilic aprotic solvent, dimethyl sulfoxide (DMSO). An increasing tendency towards molecular heteroconjugation in these systems without proton transfer has been found with increasing p K a DMSO (HA), i.e., with decreasing phenol acidity. Moreover, a linear correlation has been established between the determined lg K BHA DMSO values and p K a DMSO (HA). Furthermore, overall stability constants, lg K o DMSO , could be correlated linearly with p K a DMSO (HA) values.