Research Of Technology For The Synthesis Of γ-chloropropyl Methyl Dimethoxy Silane

Organosilieon material has excellent performance and a great variety,which arewidely used in aviation, building,transportation,electronics,medicine,food, spinning,machinery and other industrial sectors. The silane coupling agent is one of the fourpillars of organic silicon products, which can be used as raw material to preparethousands of organosilieon products.γ-Chloropropyl methyl dimethoxy silane is oneof the silane coupling agents,which is used widely in many areas，and it also can bean important intermediate to synthetise a series of γ-chloropropyl silane couplingagents.It has become one of the fastest growing materials in the new chemicalindustrial area in recent years. The synthesis of γ-chloropropyl methyl dimethoxysilane is generally through silicon-hydrogen addition reaction to add alcoholysisreaction.This paper studied on the synthesis of γ-chloropropyl methyl dimethoxysilane,γ-chloropropyl, dichloromethylsilane and methanol were used as raw materials.The synthetic route was as follow：first,γ-chloropropyl methyl dichlorosilane wassynthesized by hydrosilylation；next, the intermediate obtained in the first step andmethanol were used for alcoholysis reaction to synthesis γ-chloropropyl methyldimethoxy silane.Optimized the synthesis conditions and investigated the catalyticperformance of the catalysts.The results are meaningful for the development andindustrial applications of such products.In the hydrosilylation experiment,isopropanol solution of chloroplatinic acid wasused as catalyst, high-pressure infusion pump was used to transport γ-chloropropyl ata certain rate to the extra tight autoclave. The synthesis technologic conditions wereoptimized by orthogonal and single factor experiments，found that the most importantfactor for the hydrosilylation was reaction temperature, then the amount of catalystand the ratio of raw materials. Under optimum conditions,88.4％conversion ofγ-chloropropyl and48.9％yield of γ-chloropropyl methyl dichlorosilane were gained.The product was characterized by FT-IR and1H-NMR.Under experimental conditions optimized before, the chloroplatinic acid was used as main catalyst, PhNH2、PhNMe2、Bu3N、NEt3and PPh3were selected to bepromoters. Optimized the ratio of each promoter and the chloroplatinic acid, in thecase of each promoter mixed with chloroplatinic acid with the optimal molar ratio,investigated their effects on the catalyst performance of chloroplatinic acid,found thatthese promoters could improve the catalyst performance of chloroplatinic acid atdifferent degrees, made the reaction rate accelerated and the reaction time shorter,theconversion of raw materials and the yield of the product were both improved. NEt3was found to be the most effective one of the promoters,made the reaction timeshortened from two hours to90minutes, and the conversion of γ-chloropropylreached95.7％, the yield of γ-chloropropyl methyl dichlorosilane reached67.9％.Theresults showed that amine additives could effectively shorten the induction period andmake the catalytic performance of the chloroplatinic acid better.In the alcoholysis experiment，methanol and γ-chloropropyl methyl dichlorosilanesynthesized by hydrosilylation were used as raw materials, methanol vapor andγ-chloropropyl methyl dichlorosilane reacted in the ubular reactor with the latterdropping. The byproduct HCl generated during the reaction was excluded by passinginto dry nitrogen gas. During the reaction,no need to add any solvent, the separationand purification of the target product were greatly simplified.The synthesis technologi-c conditions were optimized by orthogonal and single factor experiments,the yield ofγ-chloropropyl methyl dimethoxy silane reached more than82％. The product wascharacterized by FT-IR and1H-NMR.