The Stability of Carboquone in Alcohols. II. : Kinetics and Mechanisms of Degradation of Carboquone in Methanol

Abstract

The kinetics and mechanisms of the degradation of carboquone (CQ) in methanol were investigated.Eight peaks were observed as degradation products of CQ in high performance liquid chromatography, suggesting that the degradation process of CQ in methanol is rather complicated. However, conducting the reaction in proton-rich methanol and methylate-rich methanol made it clear that CQ is degraded in methanol through a combination of two mechanisms : methanolysis of the aziridine ring, which cleaved to a (2-methoxyethyl)amino group, and substitution of the aziridine ring by methylate. Further, some of the degradation products were obtained in pure form by this procedure.Due to the asymmetric structure of CQ, two kinds of mono aziridinyl-mono methoxyethyl-amino compounds and two kinds of mono aziridinyl-mono methoxy compounds are produced. Kinetic studies of these four compounds and 2, 5-bis(1-aziridinyl)-3, 6-dimethyl-1, 4-benzoquinone made it possible to assign their chemical structures. Their deduced structures were confirmed by mass spectroscopy and proton nuclear magnetic resonance spectroscopy.