Highly selective monosubstitution of symmetrical dialkoxysilanes in continuous flow: Kinetics and mechanisms research

Monosubstituted symmetrical dialkoxysilanes, intermediates in the production of numerous well-known materials, present challenges for selective monosubstitution due to the presence of two alkoxy groups in similar chemical environments. Notably, kinetic studies on this phenomenon have not been documented. In addressing this knowledge gap, we developed a continuous flow system to the reaction kinetics between diethoxydimethylsilane and vinyl magnesium chloride, enhancing our understanding of these reactions. We initially analyzed the reaction order, pre -exponential factors, and activation energies systematically. The kinetic investigation revealed that the partial reaction order for diethoxydimethylsilane was first-order, the partial reaction order for vinyl magnesium chloride was also first-order, and the overall reaction order was second-order. The activation energy of the main reaction was 39.21 kJ/mol, and the activation energy of the side reaction was 59.72 kJ/mol. Therefore, precise control of the reaction conditions is essential for improving the yield. This kinetic investigation identified a potential reaction mechanism, which was later confirmed through a series of experiments. These experiments accurately determined the applicable concentration and temperature ranges for our kinetic model. Further, simulations of the model assessed the influences of reaction temperature and molar ratios on the monosubstitution selectivity, aiming to achieve controlled reaction outcomes. This study provides new insights into the reaction kinetics of Grignard reagents with symmetrical dialkoxysilanes and offers valuable guidance for optimizing reaction conditions in industrial applications. This study demonstrates selective monosubstitution of symmetrical dialkoxysilanes in a laminar flow reactor. Compared to traditional batch processes, the laminar flow reactor achieved milder conditions and higher selectivity, reaching 99.5% selectivity and 97.9% yield through kinetic studies and model simulations.