Studies on the kinetics and mechanism of drug degradation. I. Kinetics and mechanism of degradation of chlorphenesin carbamate in strongly alkaline aqueous solutions.
作者:MATSUJI HARA、HIDEHUMI HAYASHI、TSUGUCHIKA YOSHIDA、HIROSHI MURAYAMA
DOI:10.1248/cpb.34.1764
日期:——
The kinetics and mechanism of the degradation of chlorphenesin carbamate (α-CPC) in strongly alkaline aqueous solutions were studied at 0 to 20°C. The degradation did not obey pseudo-first order kinetics, but was shoun to involve a complex reaction accompanied by consecutive, parallel and reverse reactions. The rate law of degradation could be approximated in terms of specific base-catalyzed hydrolysis, that is k=kOH αOH, from the rate constant-pH profile. The Arrhenius plots of the degradation were approximately linear. Chlorphenesin-2-carbamate (β-CPC) and chlorphenesin (CP) were detected as alkaline degradation products of α-CPC.The mechanism proposed for the degradation of α-CPC involves migration of the carbamoyl group to the adjacent OH group and removal of the carbamoyl group in the presence of hydroxide ions.
研究了0~20°C强碱性水溶液中氯苯甘醚氨基甲酸酯(α-CPC)的降解动力学和机理。该降解不遵循伪一级动力学,而是避免涉及伴随连续、平行和逆反应的复杂反应。降解速率定律可以根据特定的碱催化水解来近似,即 k=kOH αOH,来自速率常数-pH 曲线。降解的阿伦尼乌斯图近似线性。检测到氯苯甘醚-2-氨基甲酸酯 (β-CPC) 和氯苯甘醚 (CP) 是 α-CPC 的碱性降解产物。α-CPC 的降解机制涉及氨基甲酰基迁移到相邻的 OH 基团并去除氨甲酰基在氢氧根离子存在下。