Mechanism research on the disproportionation for preparing dichlorodimethylsilane catalyzed by (AlCl2)+ modified 4T NaAlCl4/ZSM-5

Abstract

Disproportionation for preparing (CH₃)₂SiCl₂ can effectively solve some problems caused by the accumulation of by-products during direct synthesis. In this paper, the disproportionation for preparing (CH₃)₂SiCl₂ catalyzed by (AlCl₂)⁺ modified 4T NaAlCl₄/ZSM-5 was studied, and the reaction mechanism was investigated under B3LYP/6-311G++(3df, 2pd) basis using density functional theory. It was found that the activation energies of the rate determining step in the main reaction and side reaction were 97.89 kJ•mol^-1 and 169.50 kJ•mol^-1, respectively. Moreover, the skeleton stability of 4T cluster NaAlCl₄/(AlCl₂)⁺-ZSM-5 was higher and its activity was better than (AlCl₂)⁺ modified before due to its lower Mayer bond order and slightly larger four-center bond order. Our results from activation energy analysis, vibration analysis, IRC calculation, LOL analysis and bond order analysis showed good consistency with each other and agreed well with those of previous experiments.

KEY WORDS: AlCl₃/ZSM-5, Disproportionation, DFT, (CH₃)₂SiCl₂

Bull. Chem. Soc. Ethiop. 2019, 33(2), 269-276.

DOI: https://dx.doi.org/10.4314/bcse.v33i2.7