Kinetics and Mechanism of Decompositions of N-Methyl-N′-aryl-N-nitrosoureas and Related Compounds in Aqueous Buffer Solution

The decomposition reactions of N-methyl-N′-aryl-N-nitrosoureas (1) and of N,N′-dimethyl-N′-aryl-N-nitrosoureas (2) were studied kinetically in phosphate buffer solution. All nitrosoureas 1 were easily hydrolyzed even under neutral conditions and the rates of hydrolysis were found to be proportional to the hydroxide ion concentration over pH range 5.4–7.6. General base catalysis by buffer components was negligible. The reaction was subjected to the elimination mechanism in which an abstraction of the ureido proton was involved as an initial step. On the other hand, nitrosoureas 2 had no significant reactivity under the same conditions.