Study of the reversible reaction between the diphenylaminyl radical and sterically hindered phenol

Abstract

Two methods of determining the equilibrium constant of the reaction of the diphenyl-aminyl radical with 2,4,6-tri-tert-butylphenol were proposed; they are based on the high reactivity of aminyl radicals in cleavage of a H atom from phenol and phenoxyl radicals in cleavage of an H atom from an amine. In the first method (generation of aminyl radicals in a system containing phenol and amine), the forward reaction goes into quasiequilibrium, and the maximum concentration of phenoxyl radical formed and the concentrations of the other components calculated from the stoichiometry are used for calculating the equilibrium constant. In the second method (kinetic features of consumption of the phenoxyl radical in the presence of amine and phenol), the reverse reaction goes into quasiequilibrium, and the equilibrium constant is calculated in this case using the initial segments of the kinetic curve of consumption of phenoxyl. Both methods give similar values of the equilibrium constant.