Hydrosilylation reaction refers to the addition reaction between organosilicon compounds containing silicon-hydrogen bonds and compounds containing unsaturated bonds under certain conditions. It is the main form of silicon-carbon bonds and the most important reaction in organosilicon chemistry. One of the types, with mild reaction conditions and high reaction efficiency, it can be widely used in the synthesis of organohalosilanes, the preparation of modified silicone oil, the synthesis of silane coupling agents, the synthesis of liquid silicone rubber, and the synthesis of some functional silicone materials.
Unsaturated bonds in the hydrosilylation reaction can be carbon-carbon double bonds, carbon-carbon triple bonds, carbon-oxygen double bonds, and carbon-nitrogen double bonds. Among them, the addition reaction of silicon-hydrogen bond and carbon-carbon double bond is the most common hydrosilylation reaction in the silicone industry. This article also mainly introduces the addition reaction of silicon-hydrogen bond and carbon-carbon double bond.
According to the different catalytic systems of the reaction, the hydrosilylation reaction can be divided into two types: free radical addition mechanism and coordination addition mechanism. Under the conditions of ultraviolet rays, high temperature, γ-rays, peroxides, azo compounds, etc., the hydrosilylation reaction proceeds according to the free radical addition mechanism; under the action of transition metal catalysts such as platinum, palladium, rhodium, nickel, etc. The coordination addition mechanism proceeds. Due to the high activity and selectivity of transition metal catalysts, common hydrosilylation reactions are mainly carried out under the catalysis of transition metal catalysts, and platinum catalysts are the most widely used transition metal catalysts.
It can be seen from the hydrosilylation reaction formula that the hydrosilylation reaction mainly includes compounds containing carbon-carbon double bonds, compounds containing silicon-hydrogen bonds, and platinum catalysts, all of which are indispensable. Among them, the compounds containing carbon-carbon double bonds can be small organic molecules containing carbon-carbon double bonds, or small organic silicon molecules or high polymers containing carbon-carbon double bonds, such as vinyl silicone oil, vinyl silicone rubber, etc. And vinyl silicone resin, etc.; compounds containing silicon-hydrogen bonds, mainly including small silicone molecules containing silicon-hydrogen bonds, and silicone polymers such as hydrogen-containing silicone oil, hydrogen-containing silicone resin, and hydrogen-containing silicone rubber; platinum catalysts, currently The most widely used is Karstedt's catalyst diluted with a specific diluent. The main component is a complex of platinum and vinyl double-capped heads. It has high catalytic activity and fast reaction speed, but it is also prone to poisoning. The disadvantage of inactivation, so in the process of packaging, transportation and use, it is necessary to prevent the platinum catalyst from coming into contact with organic compounds containing nitrogen, phosphorus, sulfur and other elements and ionic compounds containing heavy metals such as tin, lead, mercury, bismuth and arsenic. It is easy to poison and invalidate the platinum catalyst.
The hydrosilylation reaction can also occur at room temperature, and the reaction speed is extremely fast after heating, and a large amount of heat will be released along with the reaction process. Therefore, when using this reaction for industrial production, attention should be paid to the order of ingredients, and the ratio of each component in the formula should also be controlled within a reasonable range to prevent affecting product performance or accidents. Usually, in addition to the three components of the carbon-carbon double bond-containing compound, the silicon-hydrogen bond-containing compound, and the platinum catalyst, a small amount of polymerization inhibitor is added to the hydrosilylation reaction. The function of the polymerization inhibitor is mainly Inhibit the reaction rate of the hydrosilylation reaction at normal temperature, but under heating conditions, the inhibitor has little effect on the reaction rate of the hydrosilylation reaction.
After understanding the various components and application fields of the hydrosilylation reaction, the specific products used in the hydrosilylation reaction can be improved by selecting raw materials with different indicators, designing different formulas and adding various types of additives. The performance of the product can be controlled by selecting platinum catalysts with different activities and changing the amount of platinum catalyst added to control the reaction speed, improve production efficiency, and finally produce products with excellent performance.
About silicone oil, please check the details:
https://www.siliconefoam.net/product-hydroxyl-blocking-polymethyl-silicone-oil-(general-type)-iota-1203-.html
