Study On Transmetal Catalysts For Hydrosilylation Of Olefins

Hydrosilylation is a common method to prepare the carbon-silicon organosilicon products. Although the hydrosilylation of olefins predominantly uses platinum catalysts in industry at present, the deficiencies are obvious. First, the platinum-containing catalysts are very expensive. The recovery of catalysts is not easy. Second, in the case of silanes with electron-donating substituents or olefins with electron-drawing substituents, hydrosilylation with platinum catalysts is not effective. In this paper, ruthenium complexes are studied as a novel catalyst of hydrosilylation. Ruthenium-containing catalysts are investigated for three kind of hydrosilylation. Catalyzed by ruthenium complexes, trimethoxysilanes reacting with varies olefins to prepare y-chloropropyltrimethoxysilanes, dodecanyl trimethoxysilanes andγ-methacryloxypropyltrimethoxysilane respectively.The main results of study in this paper are summarized below:1. Ru₃(CO)₁₂ and a carbonyl chloride ruthenium complex are synthesized and characterized by X-Ray, IR and Raman spectrometry.2. The activities of eight ruthenium-containing catalysts including K₂RuCl₅, Ru/Al₂O₃, RuO₂, Ru/C, Ru₃(CO)₁₂, RuCl₃ · 3H₂O, RuCl₂(PPh₃)₃ and carbonyl chloride ruthenium complex are investigated for the hydrosilylation of trimethoxysilanes and allyl chloride. Ru₃(CO)₁₂, RuCl₃ · 3H₂O and carbonyl chloride ruthenium exhibit a high activity. The order of activity of the three effective catalysts for the hydrosilylation of trimethoxysilanes and allyl chloride is as follows: Ru₃(CO)₁₂ > RuCl₃ · 3H₂O>arbonyl chloride ruthenium. And the activity of K₂RuCl₅ is less. The yield of hydrosilylation products catalyzed by K₂RuCl₅ is low. And the other catalysts are not effective at all. When catalyzed by Ru₃(CO)₁₂ at 80℃ and concentration of ruthenium is 20μg·g^-1, the ratio of trimethoxysilanes and allyl chloride is 1.6:1, the yield of y-chloropropyltrimethoxysilanes is more than 92%. The main product of the reaction is y-chloropropyltrimethoxysilanes, and the byproducts include propyl chloride, chlorotrimethoxysilanes, tetramethoxysilanes and propyltrimethoxysilanesetc.3. Ru3(CO)i2 is an effective catalyst for the hydrosilylation of trimethoxysilane and 1-dodecene. When catalyzed by Ru3(CO)i2 at 80°C and concentration of ruthenium is 20ug*g"1, the ratio of trimethoxysilanes and 1-Dodecene is 1.2:1, the yield of dodecanyl trimethoxysilanes is more than 62%. The order of activity of the three effective catalysts for the hydrosilylation of trimethoxysilanes and 1 -dodecene is as follows: Ru3(CO)i2 >RuCl3 ? 3H2O>carbonyl chloride ruthenium. The main product of the reaction is dodecanyl trimethoxysilanes, and the byproducts include tetramethoxysilanes et al.4. The order of activity of the three catalysts for the hydrosilylation of trimethoxysilanes and allyl methacrylate is as follows: RuCl3 ? 3H2O>Ru3(CO)i2>carbonyl chloride ruthenium. When catalyzed by RuCl3 ? 3H2O at 80 °C and concentration of ruthenium is 20ug*g'', the ratio of trimethoxysilanes and allyl methacrylate is 1.2:1, the yield of y-methacryloxypropyltrimethoxysilane is more than 54%. The main product is Y-methacryloxypropyltrimethoxysilane, and byproducts include propylene, tetramethoxysilane et al.In the case of silanes with electron-donating substituents or olefins with electron-drawing substituents, hydrosilylation with platinum catalysts is not effective. Ruthenium complexes is proved to be effective to this kind of reaction. The process of this paper uses a relatively low molar excess of the trimethoxysilanes, and can operate with a much lower level of the ruthenium catalyst, and with shorter reaction times. The process produces low levels of byproducts, and can provides a higher yield per unit volume of equipment.