Mechanism Study on the Preparation of Dimethyldichlorosilane Catalyzed by -Al2O3

Disproportionation method for the preparation of dimethyldichlorosilane can effectively solve a series of problems caused by the accumulation of by-products generated by direct synthesis. This method can turn wastes into treasures but the mechanism is still unknown. The B3LYP/6-31G and MP2/6-311++ G(3df, 2pd) methods were used to calculate the mechanism of the disproportionation catalyzed by -Al2O3. The results showed that the active center of the reaction system of -Al2O3 is proton. The first step and the fifth step were the rate-limiting step of main reaction and side reaction respectively, which the activation energy barrier is 151.60 and 389.25 (kJ•mol-1) respectively. By comparing the activation energy values, it was found that the reaction path which produce the main product dimethyldichlorosilane could proceed smoothly, and thus matches the results of the experiments.