新农药硫肟醚的水解研究  

Hydrolysis of Novel Insecticide Sulfoxime in Buffered Solutions

作　　者：欧晓明[1] 雷满香[1] 裴晖[1] 任竞[1] 柳爱平 王晓光 

机构地区：[1]湖南化工研究院农药剂型与应用系统研究所,湖南长沙410007 [2]国家农药创制工程技术研究中心,湖南长沙410007

出　　处：《农业环境科学学报》2007年第6期2309-2315,共7页Journal of Agro-Environment Science

基　　金：国家科技攻关项目(2001BA308A02-10;2004BA308A21-4);湖南省自然科学基金项目(06JJ20054)

摘　　要：硫肟醚[O-(3-苯氧苄基)-2-甲硫基-1-(4-氯苯基)丙基酮肟醚]是具有我国自主知识产权的一种新型杀虫剂品种,主要用于防治蔬菜和茶树害虫。报道了硫肟醚在不同pH值和温度下的水解动态及其机理。结果表明,硫肟醚在缓冲溶液中的水解反应比较缓慢,其水解反应速率随反应介质pH值的增大而稍有增加。在25℃时其在pH5、7和9的缓冲液中的水解半衰期分别为1257、879和492d,说明硫肟醚在水体中较稳定,不易分解,但总的趋势是在碱性条件下的水解速率较中性和酸性条件下快。硫肟醚在水体中的水解速率随温度升高而加快,在温度为15、25、35、45℃的pH7缓冲液中的水解半衰期分别为1092、879、490和399d,温度效应系数Q为1.23～1.8。硫肟醚水解反应的活化能与温度之间无明显相关性,其平均活化能和活化焓均较小,分别为28.13kJ·mol-1和25.58kJ·mol-1。而硫肟醚水解反应的活化熵绝对值随温度升高而增加,表现出显著的相关性,其平均活化熵为-219.97kJ·mol-1·K-1,表明硫肟醚在水溶液中的水化学降解主要是由反应的活化熵所驱动的。采用制备HPLC和LC-MS技术对硫肟醚水解产物进行分离和鉴定,初步确定硫肟醚分子在水溶液中生成的水解产物主要有1-(4-氯苯基)-2-(甲基磺酰基)丙烷-1-亚胺、2-甲硫基-1-(4-氯苯基)丙胺、1-(4-氯苯基)-2-(甲基磺酰基)丙基-1-酮肟醚、O-(3-苯氧苄基)-1-(4-氯苯基)丙基酮肟醚和硫肟醚亚砜等,推测硫肟醚的主要水解途径有肟醚键断裂、硫醚氧化和S-脱甲硫基作用等。Sulfoxime [O-（3-phenoxybenzyl）-2-methylthio-1-（4-chlorophenyl）propyl ketone oxime] is a novel oxime insecticide discovered and developed by Hunan research institute of chemical industry, which has been used to effectively control the pests in vegetables and tea plants. The hydrolysis kinetics and mechanisms of sulfoxime were studied in buffered aqueous solutions within the pH of 5-9 at ambient temperature of 25 ℃ and at pH 7 under 15 ℃～45 ℃. The results showed that sulfoxime hydrolyzed very slowly in the buffered solutions, and its hydrolysis rate was characterized by a first-order kinetics, pH- and temperature-dependent, and accelerated by the basic conditions and higher temperature. The calculated half lives of sulfoxime hydrolysis in the solutions of pH 5, 7 and 9 were 1 257 d, 879 d and 492 d at 25℃, respectively, indicating that sulfoxime was very stable in the aqueous environments, but the whole trend was that sulfoxime hydrolyzed much faster in the basic solution than in acidic and neutral solution at the same temperature. The hydrolysis rate of sulfoxime increased as the temperature went up, and its half lives in the buffered solution of pH 7 were 1 092 d, 879 d, 490 d and 399 d at 15 ℃, 25℃, 35℃ and 45℃, respectively. The temperature coefficient of hydrolysis for sulfoxime was 1.23-1.8. There existed no obvious correlations between the activation energies of sulfoxime hydrolysis and temperatures, and its average activation energy and activation enthalpy were 28.13 kJ·mol^-1 and 25.58 kJ·mol^-1, respectively. The activationentropy absolute values of sulfoxime hydrolysis increased with the increasing temperatures in the environment, and averaged-219.97 kJ·mol^-1·K^-1, suggesting that hydrolysis of sulfoxime in the aqueous solutions was driven by the activation entropy. Through isolation and identification of sulfoxime hydrolytic products using preparative HPLC and LC-MS technique, it was found that sulfoxime was degraded largely via the routes such as oxime ether （-C=N-O-）

关 键 词：硫肟醚 水解动力学 水解机理 活化能 活化熵 

分 类 号：X592[环境科学与工程—环境工程]