Kinetics and mechanism of solvolysis of N-aryl sulfuric diamides

Abstract

The methanolysis and hydrolysis kinetics have been studied with the following sulfuric diamide derivatives: N-methyl-N-phenyl- (IIIa), N-methyl-N-(4-methoxycarbonylphenyl)- (IIIb), N-(4-methoxycarbonylphenyl)- (IIIc), N-methyl-N-(2-methoxycarbonylphenyl)- (IIId), N-(2-methoxycarbonylphenyl)- (IIIe), and N-methyl-N-(2,4-dibromophenyl)- (IIIf). The solvolyses of the neutral substrates IIIa and IIIb proceed by the addition-elimination mechanism. In the presence of the solvent lyate ions the solvolyses go by the E1cb mechanism. The solvolyses of the conjugated bases of compounds IIIa and IIIb are subject to general acid catalysis, the effects of the ring substituents being opposite to those in the addition-elimination mechanism. The solvolyses of compounds IIId and IIIf exhibit a distinct catalytic effect of neighbouring group; the reaction goes via a reactive intermediate, the transformation of the intermediate into the solvolysis product being subject to general acid and base catalysis.