Study On The Synthesis Of New Efficient Herbicide Mesotrion

Mesotrion is a kind of triketone herbicides, which is developed by Syngenta Participations AG in Switzerland. It is sold by its brand name callisto in Europe since 2001, and authorized to produce in the same year by the United States environmental protection agency, due to its friendly to environment. Its single and mixed agent are sold and widely applied in 2002 in European Union and U.S.In the paper, the synthetic routes and processes of mesotrion were investigated in detail and the aim was to reduce production costs, improve the reaction yield, simplify process operation and be applied in industry. The dissertation included seven chapters:In the first Chapter, it summarized the current situation and development trend of pesticide in china. Then the development history, action principle, weeding behavior and classification of herbicide were summarized, and the detected method by HPLC was introduced. The preparation knowledge was necessary for our works.In the second chapter, mesotrion with physical and chemical properties and development process was discussed and its chemical structure was given. In the synthesis of mesotrion, compound intermediate,4-methylsulfonyl-2-nitrobenzoic acid was a key by the inverse synthetic analysis. On the basis of a mass of related references and experiment research, several practical synthesis routes were proposed. A feasible production process was attained. In the experiment,4-methyl benzenesulfonyl chloride as starting material, mesotrion was attained by a series of chemical reactions, including reduction, sulfonylation, nitration, oxidation, chlorination, condensation rearrangement.In the third to sixth chapter, the synthetic route was optimized, appropriate raw material was screened and the optimum process and separation methods were determined. In the process of reduction and sulfonylation of 4-methylbenzenesulfonyl chloride, the target product had high yield with 92% using sodium sulfite as reducing agent and sodium chloroacetate as sulfonylation reagent. The production with high yield of 96.2% was attained by nitration reaction, which was conducted by nitration mixture. In this process, there are some advantages, including less by-products and higher purity. In the process of oxidating 2-nitro-4-methylsulfonyltoluene by strong nitric acid, V2O5 was used as catalyst, which was good for postprocessing and requiring low pressure during the reaction. The chlorination reaction with yield 92% by means of thionyl chloride as chlorinated agent and DMF as solvent was obtained. The aim production with yield 80% was synthesized by the condensation reaction between 4-mesyl-2-nitro-benzoyl chloride and 1,3-Cyclohexanedione under the reation condition of ethylene dichloride as solvent, triethylamine as the bind acid agent, and acetonitrile as rearrangement catalyst.In the chapterⅦ, the major results and the prospects for the further research were reviewed.