Study On Hydrosilylation Of Dimethylchlorosilane

Reactive carbon functional group terminated silanes are widely used in the preparation of silane coupling agent, modification of organic polymer and daily necessities. An important method to synthesize carbon functional group terminated silane is hydrosilylation of hydride silane and unsaturated hydrocarbon.Trichlorosilane, dichloromethylsilane and dimethylchlorosilane are all hydride silanes. Dimethylchlorosilane is the least reactive and till now scientists are paying more attention on the research of trichlorosialne and dichloromethylsilane, but the products of hydrosilylation of dimethylchlorosilane are important carbon functional silanes in organic silicon industry.The research purpose was to synthesize the products of hydrosilylation of dimethylchlorosilane, and the main research work was summarized as follows:(1) 1,3-bis(y-chloropropyl)-1,1,3,3-tetramethyldisiloxane was synthesized via hydrosilylation and hydrolytic condensation. With dimethylchlorosilane and allyl chloride as raw materials, reaction intermediate y-chloropropyldimethylchlorosilane was obtained by hydrosilylation, then hydrolyzed to produce 1,3-bis(y-chloropropyl)-1,1,3,3-tetramethyldisiloxane.The factors that influence the yield of hydrosilylation reaction was investigated, such as the type and amount of catalyst, the mixing way of reactants, reaction time and the ratio of reactants. Through the experiments, the optimized conditions were found:the catalytic efficiency and economic benefits were considered at the same time,2×10-5 g/mL H2PtCl6 (the concentration of Pt in reaction system) was chosen as catalyst, the ratio of reactants was 1:1, mixing reactants together and the reaction time was 5 h. Under the optimized conditions, the yield of hydrosilylation could reach 83.8%. The yield of hydrolytic condensation was 96.7%. And the total yield of product was 81%.IR,'H NMR and GC-MS were used to characterize the structure of reaction intermediate and target product.(2) The mechanism of hydrosilylation reaction catalyzed by platinum was studied with chloroplatinic acid catalyzed hydrosilylation of dimethylchlorosilane and allyl chloride as the study object. Field emission transmission electron microscopy was used to observe the morphology change of platinum catalyst before and after reaction. Chloroplatinic acid was found to be reduced to Pt nanopaticles. The energy change of hydrosilylation was calculated and studied using the theory of quantum chemistry, which was helpful to know the reaction mechanism of hydrosilylation.(3) Methacryloxypropyldimethylchlorosilane was prepared via hydrosilylation of dimethylchlorosilane and allyl methacrylate. The effect of temperature, type and amount of catalyst on yield were studied. With the optimized conditions of 1×10-5 g/mL Karstedt catalyst (the concentration of Pt in reaction system), the reaction temperature of 55?, the yield of product was 81.8%.GC-MS was used to analyze the reaction mixtures. After studying 7 kinds of substance's fracture way, the structures of primary product and by-products were determined, and the reaction pathway was proposed. The structure of target product was characterized by IR,'H NMR.The originality in this thesis:(1)1,3-bis(?-chloropropyl)-1,1,3,3-tetramethyldisiloxane as a reactive functional group contained siloxane, was synthesized from dimethylchlorosilane and allyl chloride via hydrosilylation and hydrolytic condensation. This is a new method to prepare 1,3-bis(?-chloropropyl)-1,1,3,3-tetramethyldisiloxane. The synthesize way was easy to process and gotten less by-products.(2) The reaction mixtures of dimethylchlorosilane and allyl methacrylate were separated and analyzed by GC-MS. And the reaction pathway was studied. The work provide a theoretical guidance to optimize the reaction conditions and purify the products.