Influences of organic additives on inhibiting by-products in zinc-catalyzed synthesis of alkynylsilane
(2.School of Material Science and Engineering, East China University of Science and Technology, Shanghai, China 200237)
(3.College of Materials and Energy, South China Agricultural University, Guangzhou, Guangdong, China 510642)
【Abstract】Silylation of phenylacetylene with trimethylchlorosilane (TMCS) in the presence of zinc powder catalyst will produce around 33% alkene by-products. Different organic additives were used as H scavengers to reduce the production of styrene (ST). From the results via GC analysis, pyridine and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) were found to be effective to increase the selectivity but the conversion rate was decreased. The concentration of organic additives, reaction time and temperature were then optimized. The concentration optimization showed that 6 mol DBU was effective to decrease the generation of ST but the yield of the main product phenylethynyltrimethylsilane (PT) dropped significantly. It was found that 6 mol was the optimal pyridine concentration for its relatively high conversion and selectivity. The yield of ST decreased to around 13% while the yield of PT was 57%. The optimal reaction time was 20 h. The conversion and selectivity rarely changed with a longer reaction time. As for temperature, it was found that a higher temperature was beneficial to improve the conversion but unfavorable to selectivity. The results showed that the conversion was the highest at 110 °C while the selectivity was the best at 100 °C with 6 mol pyridine.
【Keywords】 zinc powder; silylation; alkene by-product; selectivity; catalysis; chemical reaction;
(Translated by WANG YX)
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