Study On The Acidity Problem Of Methvltrimethoxvlsilane

The acidity problem of methyltrimethoxylsilane(MTMS)has seriously affected its application.The purpose of this paper is to find out the reason of the acidity problem of MTMS and take appropriate methods to control the acid of MTMS.The reason of acidity problem of MTMS and the strategy to prevent it were studied.The results show that the main reason of acidity problem of MTMS is the isomer with a molecular formula of C6H12 in raw materials.Then several strategies were studied to solve the acidity problem of MTMS.Methyltrichlorosilane which contains unknown impurity components from Zhejiang Xin'an chemical industry group Limited Ltd was studied through GC-MS,GC for both qualitative and quantitative analysis.Meanwhile,unknown impurities in the MTMS were also qualitative analyzed.The results showed that the unknown impurity components of methyltrichlorosilane are olefins with a formula of C6H12.MTMS products contain olefin whose molecular formula is C6H12,and tert chloride alkane whose molecular formula is C6H13Cl.Its pH value is 3.0?4.5,apparent acidic.This is because tert chloride alkane is reversibly hydrolyzed producing hydrogen chloride in the water.In the process of esterification,olefins with molecular formula of C6H12 in the raw materials react with hydrogen chloride leading to the formation of chlorinated alkanes with molecular formula of C6H13Cl.In order to prevent acidity problem of MTMS,this paper proposed five solutions.1)Using methyltrichlorosilane with olefin content less than 0.05%as raw material;2)using raw material of methyltrichlorosilane after pre-distillation treatment;3)Improving the production process by stopping returning esterification tail gas condensate to the esterification system;4)using dechlorination agent for the treatment of acidic products;5)using anhydrous ferric chloride as the catalyst to enable Williamson reaction between chloralkane and sodium methoxide,then performing distillation processing.The results showed that five solutions can prevent acidity problem of MTMS to different levels,and each of them has its advantages and disadvantages.The employment of solution 1 and 5 can solve the acidity problem of MTMS satisfactorily.