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[方法]4,5-二氢-3-甲基-1-(4-氯-2-氟苯基)-1,2,4-三唑-5(1H)酮是唑酮草酯的重要中间体。以4-氯-2-氟苯肼为原料,乙酸乙酯为反应溶剂,PEG-1000为相转移催化剂,经过脱水缩合、1,3-偶极加成、氧化脱氢等3步反应,合成4,5-二氢-3-甲基-1-(4-氯-2-氟苯基)-1,2,4-三唑-5(1H)酮。[结果]研究了催化剂种类与用量、溶剂、反应温度、物料配比对反应收率的影响,得到优化后的反应条件:n(乙醛)∶n(氰酸钠)∶n(乙酸)∶n(次氯酸钠)∶n(聚乙二醇-1000)∶(4-氯-2-氟苯肼)为1.80∶1.60∶1.84∶1.60∶0.04∶1.0,反应温度20~25℃。[结论]该工艺原料易得、反应条件温和、操作简单、收率较好,具有良好的工业应用价值。
[Method] 4,5-Dihydro-3-methyl-1- (4-chloro-2-fluorophenyl) -1,2,4-triazol-5 (1H) Intermediate. Using 4-chloro-2-fluorophenylhydrazine as raw material and ethyl acetate as the reaction solvent, PEG-1000 as phase transfer catalyst was synthesized by three steps of dehydration condensation, 1,3-dipolar addition and oxidative dehydrogenation 4,5-Dihydro-3-methyl-1- (4-chloro-2-fluorophenyl) -1,2,4-triazol-5 (1H) one. [Result] The effects of the type and amount of catalyst, solvent, reaction temperature and the ratio of materials on the reaction yield were investigated. The optimized reaction conditions were as follows: n (acetaldehyde): n (sodium cyanate) n (sodium hypochlorite): n (polyethylene glycol-1000): (4-chloro-2-fluorophenylhydrazine) was 1.80: 1.60: 1.84: 1.60: 0.04: 1.0. The reaction temperature was 20-25 ° C. [Conclusion] The raw materials of the process are easy to obtain, the reaction conditions are mild, the operation is simple, the yield is good, and has good industrial application value.