Novel Triazenes and Triazolines from the Base-Catalyzed Hydrolysis of 1,3-Dialkyl-3-acyltriazenes

Article abstract of DOI:10.1021/jo00050a016

The products and mechanism of hydrolytic decomposition of a series of 1,3-dialkyl-3-acyltriazenes were studied in alkaline buffers.In general the mechanism of decomposition involves deacylation leading to the formation of the parent 1,3-dialkyltriazene.The solvent deuterium isotope effect (k_H2O/k_D2O) is less than 1.0, indicating specific base catalysis.A plausible mechanistic explanation is rapid reversible attack by hydroxide ion, followed by rate-limiting heterolysis of the N(1)-acyl bond.The resultant, 1,3-dialkyltriazene is somewhat unstable under the reaction conditions and undergoes subsequent hydrolysis, a reaction previously shown to be specific acid-catalyzed.When the N(1) alkyl group is 2-chloroethyl, unusual products are obtained.For the 3-acetyl and 3-carbethoxy derivatives, the initial deacylation product, 1-(2-chloroethyl)-3-methyltriazene, efficiently cyclizes to form 1-methyltriazoline.The 3-(methylcarbamoyl) derivative does not deacylate, but instead undergoes dehydrohalogenation to 1-vinyl-3-methyl-3-(methylcarbamoyl)triazene.