KINETICS AND MECHANISM OF ACID-HYDROLYSIS OF 1-METHYL-1-NITROSO-3-P-TOLYLSULFONYLGUANIDINE AND 1-METHYL-1-NITROSO-3-BENZOYLGUANIDINE

Kinetics of acid hydrolysis of 1-methyl-1-nitroso-3-p-tolylsulfonylgua nidine 2 and of two 1-methyl-1-nitroso-3-benzoylguanidines (4-unsubsti tuted and 4-chloro) 5 and 6 have been studied. For the acid hydrolysis of 1-methyl-1-nitroso-3-p-tolylsulfonylguanidine 2, the absence of ca talysis by thiocyanate ion, and the value of the kinetic solvent isoto pe effect indicate that either a rate determining proton transfer foll owed by fast denitrosation or a concerted pathway is involved in the m echanism. In the case of the acid hydrolysis of 1-methyl-1-nitroso-3-b enzoylguanidines 5 and 6 it was observed that the protonated form deco mposes via two parallel pathways. One involves a slow nucleophilic att ack concerted with an intramolecular proton transfer, and the other a slow concerted denitrosation, where a second proton transfer and NO+ e xpulsion are simultaneous.