The synthesis and hydrolytic decomposition of l,3-dimethyl-3-(diethoxyphosphinyl)triazene (DMP), 1,3-dimethyl-3-carboethoxjrtriazene (DMC), l,3-dimethyl-3-acetyltriazene (DMA), and l,3-dimethyl-3-(AT-methyl-carbamoyl)triazene (DMM) are described. The kinetics of hydrolysis of DMP and DMC were investigated in aqueous buffers as a function of pH. DMP was found to be subject to acid catalysis up to pH 4.5 but then followed uncatalyzed kinetics up to pH 11.5. DMC, on the other hand, was catalyzed by acid at pH <4.5 and base catalyzed at pH >9.5. It exhibited uncatalyzed kinetics in the intervening pH region. DMA and DMM also appear to follow uncatalyzed kinetics in the vicinity of neutral pH. The order of reactivity of the four triazenes at pH 7.5 was found to be DMP > DMC > DMA > DMM. The mechanism of the hydrolytic decomposition in the uncatalyzed region is seen as a direct dissociation of the acyltriazenes to the methyldiazonium ion and the respective acylamidyl anions; The intermediacy of the methyldiazonium ion during the decomposition of DMC was established by deuterium exchange studies when the decomposition was carried out in deuterium oxide buffers. The four triazenes were tested in a bacterial mutagenesis assay by using the His-strains of Salmonella typhimurium. DMP, DMC, and DMA were found to be directly acting mutagens in strains that require a base substitution to revert to wild type. These results are consistent with the methyldiazonium ion acting as the ultimate mutagen. The mutagenicity of DMC was enhanced by porcine liver esterase, which suggested that this enzyme was capable of hydrolyzing the carboethoxy group to release the highly reactive dimethyltriazene.
ASJC Scopus subject areas
- Organic Chemistry