Dynamic Equilibrium of Forward and Reverse Chain Reactions in the Quinoneimine-Hydroquinone System

摘要

Both reactions proceed until the deficient component is consumed almost completely;i.e.,they do not exhibit pronounced reversibility.However,a study of the effect of 4-hydroxydiphenylamine HQIH additives on the rate (w_0)of the reaction of QI with 2,5-di-tert-butylhydroquinone [3,4]provided the first piece of evidence for reversibility of some elementary steps of the (gross)reaction (s).It was found that,at low concentrations of HQIH,the reaction rate w_0 first increases and then,upon further increase in [HQIH]_0,decreases.The experimental results were interpreted quantitatively with the assumption that,in the presence of HQIH,one chain termination step and one chain propagation step that involve HQIH become reversible.