Charge Transfer Interaction and Chemical Reaction. III. Reactions of m-Phenylenediamine and Related Compounds with Chloranil

The interactions of chloranil with several aromatic amines were studied by measuring visible and ultraviolet absorption spectra at various temperatures between 70°K and 300°K, m-aminophenol, m-phenylenediamine, N,N-dimethyl-m-phenylenediamine, 1,3,5-triaminobenzene, and 1-methyl-2,4,6-triaminobenzene being taken as electron donors. The m-phenylenediamine-chloranil system was studied in detail and outer and inner complexes were found to exist as reaction intermediates. The structure and stability of the inner complex were discussed. Kinetic studies were made for the m-phenylenediamine-chloranil and 1,3,5-triaminobenzene-chloranil systems. The enthalpy change, ΔH, for the formation of the outer complex was determined from the temperature dependence of the equilibrium constant. The activation energies, ΔE1 and ΔE2, for the processes from the outer complex to the inner complex and from the inner complex to the succeeding intermediate, respectively, were determined by analysing the time dependence of the absorptionpeak intensity of the inner complexes measured at several temperatures. The results are as follows: ΔH=−3.7, ΔE1=10, and ΔE2=22 (kcal/mol) for the m-phenylenediamine-chloranil system; ΔH=−2.6, ΔE2=16, and ΔE2=14 (kcal/mol) for the 1,3,5-triaminobenzene-chloranil system.