Collect. Czech. Chem. Commun. 1981, 46, 2091-2103

Solvent effect as a criterion of solvolysis mechanism. Solvolysis of 3-acyl-1,3-diphenyltriazenes

Oldřich Pytela, Petr Svoboda and Miroslav Večeřa

Department of Organic Chemistry, Institute of Chemical Technology, 523 10 Pardubice


Solvent dependence of hydrolysis rate constants of 3-acetyl-1,3-diphenyltriazene (I) and 3-(N-methylcarbamoyl)-1,3-diphenyltriazene (II) has been followed in the solvent mixtures ethanol-water, methanol-water, dioxane-water, and formamide-water within the mole fraction x = 0.0 to 0.5 at 25, 35 and 45 °C. A criterion has been suggested, based on sign of change of logarithm of the observed rate constant in dependence on change of the solvent composition, for evaluation of the reaction molecularity and, hence, participation of water in the hydrolysis mechanism. It has been found that water takes part as a proton donor in the transition state of hydrolysis of the substrates studied.