Collect. Czech. Chem. Commun. 1987, 52, 2217-2224

Kinetics and mechanism of acid catalyzed decomposition of substituted 1,3-diphenyltriazenes

Petr Svoboda, Oldřich Pytela and Miroslav Večeřa

Department of Organic Chemistry, Institute of Chemical Technology, 532 10 Pardubice


The kinetics of acid catalyzed decomposition of 3-substituted and 1,3-disubstituted 1,3-diphenyl-3-methyltriazenes have been studied in 40% aqueous ethanolic buffers at 25 °C. The reaction constant for substitution of the phenyl ring at the 3 position of the triazene chain has been determined and the reaction constants of the protonation and bond splitting between the nitrogen atoms 2 and 3 have been estimated. By the covariance analysis it has been found that the standard constants of the Hammett relation are better than the constants determined in the media of organic solvents. Also estimated were the values of the slope β1g of the linear relation between the rate constants and the equilibrium between the diazonium salt and diazotate. The A-SE2 mechanism is suggested as probable, the bond between nitrogen atoms of triazene chain being more than half split in the transition state and the nitrogen-proton bond formation being more advanced than the nitrogen-nitrogen bond splitting.