| 常用缓冲溶液对解草唑水解的催化效应研究 |
| 摘要点击 3337 全文点击 2243 投稿时间：2007-09-29 修订日期：2007-11-11 |
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| 中文关键词 解草唑 水解 缓冲催化 降解机制 |
| 英文关键词 fenchlorazole-ethyl hydrolysis buffer catalysis degradation mechanism |
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| 中文摘要 |
| 研究了温度、pH值以及常用缓冲溶液对解草唑水解的影响.结果表明，解草唑在不同pH值和温度下的水解遵循一级动力学反应，其水解速率随着pH和温度的升高而增大.利用Bronsted酸碱催化理论推导了所用缓冲溶液对解草唑水解的影响，结果表明缓冲溶液对解草唑水解存在明显的催化作用，加快了解草唑的水解速率.而且不同缓冲盐体系的缓冲催化能力也不同，同一缓冲盐体系在不同pH值条件下的缓冲催化能力也不同.其中pH = 7的磷酸盐缓冲溶液表现出最大的催化作用.通过建立基于缓冲因子校正的以温度和pH值为变量的方程，预测了模拟天然水体中解草唑的水解半减期，结果表明其水解半减期为7～790 d.液相色谱-质谱分析表明，在碱性条件下(pH 8～10)，解草唑通过乙酸乙酯基团水解生成解草唑酸. |
| 英文摘要 |
| The purpose of this study was to elucidate the effects of temperatures, pH levels and buffer catalysis on the hydrolysis of FCE. The hydrolysis of FCE follows first-order kinetics at different pH levels and temperatures. FCE hydrolysis rates are greatly increased at elevated pH levels and temperatures. The maximum contribution of buffer catalysis to the hydrolysis of FCE was assessed based on application of the Bronsted equations for general acid-base catalysis. The results suggest that the buffer solutions play an obvious catalysis role in hydrolysis of FCE and the hydrolysis rates of FCE are quickened by the buffer solutions. Besides, the buffer catalysis capacity of different buffer solutions is diverse, and the buffer catalysis capacity at different pH levels with the same buffer solutions is different, too. The phosphate buffer at pH = 7 shows the maximal buffer catalysis capacity. The hydrolysis rate constants of FCE as a function of temperature and pH, which were remedied by the buffer catalysis factor, were mathematically combined to predict the hydrolytic dissipation of FCE. The equation suggests that the hydrolysis half-lives of FCE ranged from 7 d to 790 d. Hydrolysis metabolites of FCE were identified by liquid chromatography-mass spectrometry. In basic conditions (pH 8_10), fenchlorazole was formed via breakdown of the ester bond of the safener. |
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