Study On Ruthenium-Catalyzed Hydrosilylation And Dynamics

Ruthenium catalysts are wildly applied in the field of organic synthesis. Some of ruthenium catalysts have also been used in the hydrosilylation. However, these studies are mainly concentrated in used in hydrosilylation of alkyne. Until now, for less application in the field of the hydrosilylation of olefin, and the catalytic effect of ruthenium in hydrosilylation of olefin is not very good. Based on this, activity of the catalyst, selectivity of products and the stability of catalyst, the problems existing in the hydrosilylation of olefin has also been analyzed in this paper. Research results show that the catalytic activity of oxidation state ruthenium catalysts is better than reducing state ruthenium catalysts in the hydrosilylation of olefin. Therefore, propose that the deactivation of oxidation state ruthenium catalysts may be avoided by adding additives. The catalytic system of ruthenium-catalyzed hydrosilylation of olefin has been designed and improved. Rich electronic elementary substance or compound was applied in hydrosilylation of ethylene and hydrogen siloxane as a promoter of transition metal ruthenium catalyst. Explored the relationship between the different types of promoter and catalyst performance, promoting mechanism was discussed preliminarily.The study found that elementary substanceand or compound which can offer electron can obviously improve the activity and selectivity of ruthenium catalyst in hydrosilylation of ethylene with trialkoxysilane. The kind of elementary substance and properties of compounds have an important influence on the experiment results of hydrosilylation of ethylene with trialkoxysilane. By contrast, the rich electronic elementary substance has better effect as additive, the effect of elementary substance bromine is best. By using elementary substance bromide as promoter in RuCl3·3H2O-catalyzed hydrosilylation of ethylene with trimethoxysilane,99.5%conversion as well as95.8%selectivity of target product could be obtained under the conditions of n(Ru)/n(Br2)=1/10, n(Ru)/n(trimethoxysilane)=1.8×10-4. The effect of the elementary substance iodine is second only to elementary substance bromide. By using elementary substance iodine as promoter in RuCl3·3H2O-catalyzed hydrosilylation of ethylene with trimethoxysilane,97.8%conversion as well as97.3%selectivity of target product could be obtained under the conditions of n (Ru)/n (I2)=1:10, n (Ru)/n (trimethoxysilane)=1.8×10-4In order to explore catalytic reaction mechanism of promoter in the ruthenium-catalyzed hydrosilylation of ethylene with trimethoxysilane, elementary substance iodine was integrated into catalyst, the study result show that the iodine ion has no obvious promoting role in the ruthenium-catalyzed hydrosilylation of ethylene with trimethoxysilane. However, when rich electronic compound replaced iodine elementary substance as cocatalyst, rich electronic compounds has better catalytic effect than iodine elementary substance in the ruthenium-catalyzed hydrosilylation of ethylene with trimethoxysilane. In this kind of compounds, the effect of cuprous chloride is the best. By using cuprous chloride as promoter in ruthenium-catalyzed hydrosilylation of ethylene with triethoxysilane,99.9%conversion as well as97.5%selectivity of target product could be obtained under the conditions of n(Ru)/n(CuCl)=1:10, n(Ru)/n(triethoxysilane)=1.4×10-5.In addition, the effect of the clean and undefiled, low cost and extensive source polar compounds water and alcohol on ruthenium-catalyzed hydrosilylation of ethylene with trialkoxysilane was also discussed in this article. The experiment results show not only rich electronic elementary substance and compound can improve the target product selectivity and conversion of raw material but also polar compounds water and alcohol can also greatly improve the target product selectivity and conversion rate of raw material of ruthenium-catalyzed hydrosilylation of ethylene with trialkoxysilane. Catalytic effect decreased with the decreasing polarity of polar compounds. The catalytic activity of the main catalyst RuCl3·3H2O and the selectivity of the target product can be increased significantly with the increase of the amount of cocatalyst CuCl, at the same time, the dosage of the catalyst RuCl3·3H2O can be reduced greatly. Polar compound water was used as promoter of RuCl·3H2O catalyzed hydrosilylation of ethylene with trimethoxysilane,99.4%conversion and98.1%selectivity of target product could be obtained under the conditions of n (Ru)/n (H2O)=1:111n(Ru)/n (trimethoxysilane)=8.4×10-6. The effect of the methanol is inferior to water, by using methanol as promoter,88.7%conversion as well as97.0%selectivity of target product could be obtained under the conditions of n (Ru)/n (MeOH)=1:100, n (Ru)/n (trimethoxysilane)=9.0×10-6.In order to achieve recycling reuse of the catalyst, according to the above experiment results, RuCl3·3H2O/AC (activated carbon), RuCI3·3H2O/γ-Al2O3and RuCl3·3H2O/4A-molecular sieve supported catalyst were prepared in this paper, and the catalytic performance of different supported catalyst were examined, the experiment results show that under the conditions of the same concentration, the effect of supported catalyst is not as good as homogeneous catalyst. Catalytic effect is significantly increased with the increase of the dosage of RuCl3·3H2O/AC, but the reusability is not ideal. Supported catalyst both RuCl3·3H2O/γ-Al2O3and RuCl3·3H2O/4A-molecular sieve have no any catalytic activity in the hydrosilylation of ethylene with trimethoxysilane though the dosage of RuCl3·3H2O/γ-Al2O3and /4A-molecular sieve have been increased. Therefore, AC (activated carbon) can be used as catalyst supporter, the preparation technology and method of supported catalyst remains to be further optimized.