Study On The Synthesis And Industrialized Technology Of Methyl 2-Fluoroisobutyrate

The structure and variety of pesticide change very quickly under increasing concern about environmental protection and sustainable development of agriculture.The modern pesticide has high herbicidal activity, safety and lower residue.The study on fluoro-containing herbicide becomes an important aspect of research on modern pesticide,because the herbicide containing fluorine atoms or fluorinated groups(for example trifluoromethyl, trifluoromethoxy,difluoromethyl,difluoromethyl and so on)has higher herbicidal activity than ones containing other groups.Based on the evaluation of the bibliographer and the analysis of the principle of reactions,Methyl 2-fluoroisobutyrate,the key intermediates in the synthesis of triazine herbicides,was synthesized from methyl 2-hydroxyisobutyrate,thionyl chloride and fluorine hydride by esterification and fluorine substitution.The influences of esterification and fluorination reaction were investigated in molar ratio,temperature,time and charging-up mode and so on.Optimum reaction conditions of esterification were selectred as follows:n(thionyl chloride):n(methyl 2-hydroxyisobutyrate)=1:1.7, -10～0℃,3～5h.Optimum reaction conditions of fluorination were selected as follows:pyridine as catalyst,its dosage is 2～3%based on the amount of methyl 2-hydroxyisobutyrate,n(HF):n(methyl 2-hydroxyisobutyrate)=1: 10,40℃,3～5h.The yield of Methyl 2-fluoroisobutyrate was more than 75%.Based on the results of experiments,the rational scheme for the renovating of the process was discussed.The novel process and reactors, stirring device,separate system etc.were designed.The total yield of the product in the pilot experiment reached about 74.2%.The results of the process data in test were accorded with those of the experiments.There were several typical advantages of the novel process such as the better safety, stability of the process and the low-cost of the product.It provided the theoretical basis for the industrial production of Methyl 2-fluoroisobutyrate and the fluoro-containing herbicide.