Studies on formaldehyde resins, 18. Kinetics of acid-catalyzed hydrolysis of bis(hydroxymethyl)melamine

Kinetics and mechanism of the acid-catalyzed hydrolysis of N,N′-bis(hydroxymethyl)melamine [6-amino-2,4-bis(hydroxymethylamino)-1,3,5-triazine] (M2F) were studied in the pH region of 0,5 ? 7,6 at 30°C, where 30 vol.-% DMSO aqueous solution was used as a solvent. The main results are as follows. The hydrolysis of M2F was of ca. 1,5th order in [M2F]₀ at constant pH of 2,7 ? 7,6, and was of ca. 1st order in the strongly acidic region of pH 0,5 ? 1,0. Moreover, the hydrolysis rate of M2F attained a maximum at pH 4,0 corresponding to [HCl]₀/[M2F]₀ = 0,5 and a minimum at pH 1,9. On the basis of these results and kinetic investigations, the main reaction of the hydrolysis of M2F is plausible to be a reaction of the conjugate acid of M2F with a M2F molecule in the acidic range of pH > 2,7.