Research On The Direct Synthesis Of Dimethyldichlorosilane

Organosilicone materials are composed of silicon rubber, silicon oil and its secondary product, silicone, and silane coupling agent four kinds of products, which are widely used and praised as'monosodium glutamate in the industry'. Chlorosilanes are the foundation of the organosilicone industry. And the Rochow direct process (silicone and methyl chloride under catalysis to form methyl chlorosilane) is the core technique of the production of methyl monomers of organosilicones. In this paper the influencing factors of the direct process and the analytical method of methylchlorosilanes are investigated.Methylchlorosilanes are synthesized by the direct process in a fluidized bed with its inner diameter 25mm and Cu/Cu/Cu₂O as its catalyst. According to the experiment, there is a induction period during the reaction, and methylchlorosilanes can be synthesized under the temperature of 290-330℃. During the reaction, the content of dimethyldichlorosilane first rises and then falls;as the reaction is a high exothermic reaction the temperature control during the reaction is of primary significance and the reactor should bear good heat releasing characteristics;as water in the reactor and the reactants has great influences on the selectivity of dimethyldichlorosilane, moisture in the fluidized bed, the pipelines, methyl chloride, and silicone should be removed before reaction;after reaction, the surface of silicone is analyzed by SEM and obvious pits where active Cu₃Si is formed can be discerned, which accords with the g-s-s catalytic mechanism.The methylchlorosilane product in the direct synthesis is a complex compound, which contains dimethyldichlorosilane as the majority and some trimethylchlorosilane, methyltrichlorosilane, low-boiling products and high-boiling products. With GC-MS the three main products can be detected. Using OV-210 capillary column and FID detector with benzene as the internal standard, the three main products can be analyzed quantitatively. The method is proved to be precise and accurate. As in thepacked column used in the industry now many byproducts in the direct process cannot be detected, the method lays the foundation for further quantitative analysis of some byproducts in the direct synthesis.