The stability of carboquone in alcohols. I. Kinetics and mechanisms of degradation of 2,5-bis(1-aziridinyl)-1,4-benzoquinone in alcohols.
作者:AKIRA KUSAI、SEIJI TANAKA、SEIGO UEDA
DOI:10.1248/cpb.33.2983
日期:——
The kinetics and mechanisms of the degradation of 2, 5-bis (1-aziridinyl)-1, 4-benzoquinone (I) in alcohols were investigated and compared with those in aqueous solution obtained previously. The degradation of I in alcohols follows pseudo first-order kinetics as did that in aqueous solution. Degradation rates in a series of alcohols show a good correlation with Kosower's Z-values (empirical measures of solvent polarity). Degradation mechanisms of I in alcohols were investigated in methanol, where the degradation rate of I is relatively high, being suitable for detailed study. Five compounds were observed as degradation products of I in methanol, and the degradation process of I appeared to be rather complicated. However, the degradation behavior of I and some of these five degradation products in proton-rich methanol and methylate-rich methanol allowed us to deduce the chemical structures of all the degradation products : 5-(1-aziridinyl)-2-(2-methoxyethyl) amino-1, 4-benzoquinone, 2, 5-di (2-methoxyethyl) amino-1, 4-benzoquinone, 5-(1-aziridinyl)-2-methoxy-1, 4-benzoquinone, 2, 5-dimethoxy-1, 4-benzoquinone and 5-methoxy-2-(2-methoxyethyl) amino-1, 4-benzoquinone. Their behavior also made it clear that I is degraded in methanol through a combination of two mechanisms : methanolysis of the aziridine ring, which is cleaved to a methoxyethylamino group, and substitution of the aziridine ring by a methoxy group. Therefore, the degradation mechanisms of I in methanol are concluded to be essentially the same as those in aqueous solution.
研究了2,5-双(1-氮杂环丙烷基)-1,4-苯醌(I)在醇类中的降解动力学和机制,并与之前在水溶液中获得的结果进行了比较。I在醇类中的降解遵循伪一级动力学,和在水溶液中的表现相同。在一系列醇中,降解速率与Kosower的Z值(溶剂极性的经验测量值)之间表现出良好的相关性。I在甲醇中的降解机制被仔细研究,因为I的降解速率相对较高,适合进行详细研究。在甲醇中观察到了五种化合物作为I的降解产物,I的降解过程看起来相当复杂。然而,I及这五种降解产物在质子丰富的甲醇和甲基化丰富的甲醇中的行为使我们能够推断出所有降解产物的化学结构:5-(1-氮杂环丙烷基)-2-(2-甲氧基乙基)氨基-1,4-苯醌,2,5-二(2-甲氧基乙基)氨基-1,4-苯醌,5-(1-氮杂环丙烷基)-2-甲氧基-1,4-苯醌,2,5-二甲氧基-1,4-苯醌和5-甲氧基-2-(2-甲氧基乙基)氨基-1,4-苯醌。它们的行为还清楚表明,I在甲醇中通过两种机制的组合进行降解:环氮杂烯的甲醇解作用,生成甲氧基乙基氨基,和环氮杂烯被甲氧基替代。因此,I在甲醇中的降解机制与在水溶液中的基本相同。