农业环境科学学报2013，Vol.32Issue(8)：1537-1544,8.DOI:10.11654/jaes.2013.08.007
新除草剂甲硫嘧磺隆的水解动力学与机理研究
Kinetics and Mechanisms of Novel Sulfonylurea Herbicide Methiopyrisulfuron Hydrolysis
摘要
Abstract
Methiopyrisulfuron (test code:HNPC-C9908),chemical name:methyl 2-(4-methoxy-6-methylthio-pyrimidin-2-yl) carbamoylsulfamoyl benzoate,is a novel sulfonylurea herbicide researched and developed by Hunan Research Institute of Chemical Industry,which has been used for weed control in wheat.Hydrolysis kinetics and mechanisms of methiopyrisulfuron in the aqueous solutions were studied in the laboratory using HPLC and LC-MS.Results showed that the hydrolytic degradation of methiopyrisulfuron followed first-order kinetics,and the degradation of the herbicide was dependent on the factors such as pH,temperature,clay minerals and surfactants.In the range of pH 1～10,the hydrolysis rate of methiopyrisulfuron decreased slowly with the increasing pH value,and reached the lowest value at pH 7,and increased significantly after that,and reached the maximum at pH 10.The calculated half-lives of methiopyrisulfuron at pH 1,2,3,4,5,6,7,8,9 and 10 were 20.03,25.48,33.36,36.10,55.45,64.78,216.61,169.06,4.26 and 1.17 days,respectively.The hydrolysis rate of methiopyrisulfuron in the buffer solution of pH 5,7 and 9 increased significantly with the increasing temperature.The average activation energy (Ea),enthalpy(△H) and entropy (△S) was calculated as 310.86 kJ· mol-1,308.37 kJ· mol-1 and 1.65 × 10-1 kJ· mol· K-1 at pH 5,230.59 kJ ·mol-1,228.81 kJ ·mol-1 and 2.22×10-2 kJ·mol·K-1 at pH7,and 148.67 kJ·mol-1,146.17kJ·mol-1 and-5.13×10-2 kJ·mol·K-1 at pH 9,respectively,which is required for the hydrolytic degradation of the herbicide,indicating that the hydrolysis was largely driven by the activation entropy.There was less significant difference between the hydrolysis rate constant of methiopyrisulfuron in the sterilized water and non-sterilized water from pond water and rice fields,indicating that microorganisms in the water had little impact on hydrolysis of methiopyrisulfuron.The surfactant 0205 obviously promoted the hydrolysis of methiopyrisulfuron,but no obvious effect of surfactant EL-40 and NP-20 was found.Clay minerals such as bentonite slowed down hydrolysis of methiopyrisulfuron in the aqueous solution.Through the isolation and identification of hydrolysis products of methiopyrsulfuron in pH5,7 and 9 solution by LC/MS,it was proposed that the major hydrolysis pathway of methiopyrisulfuron involved in the sulfonylurea bridge cleavage of the parent molecule to give the four main hydrolytic products such as 4-methoxy-6-(methylthio) pyrimidin-2-amine,4-methoxy-6-(methylsulfinyl) pyrimidin-2-amine,methyl-2-sulfamoyl benzoate and methyl 2-sulfinyl benzoate.关键词
磺酰脲类除草剂/甲硫嘧磺隆/水解动力学/水解机理Key words
sulfonylurea herbicide/ methiopyrisulfuron(HNPC-C9908)/ hydrolysis/ mechanisms分类
资源环境引用本文复制引用
欧晓明,步海燕,裴晖,唐德秀,黄明智,付启明,雷满香,喻快..新除草剂甲硫嘧磺隆的水解动力学与机理研究[J].农业环境科学学报,2013,32(8):1537-1544,8.基金项目
国家科技支撑计划课题(2011BAE06A01) （2011BAE06A01）
国家自然科学基金(21272062) （21272062）
湖南省自然科学基金项目(09JJ3015) （09JJ3015）
