Hydrosilylation reaction refers to the addition reaction between silicone compounds containing silicon hydrogen bonds and compounds containing unsaturated bonds under certain conditions. It is the main form of forming silicon carbon bonds. It is one of the most important reaction types in silicone chemistry. The reaction conditions are mild and the reaction efficiency is high. It can be widely used in the synthesis of organohalosilanes, the preparation of modified silicone oil The synthesis of silane coupling agent, liquid silicone rubber and some functional silicone materials.

Unsaturated bonds in hydrosilylation can be carbon carbon double bonds, carbon carbon triple bonds, carbon oxygen double bonds and carbon nitrogen double bonds. Among them, the addition reaction between silicon hydrogen bond and carbon carbon double bond is the most common silicon hydrogen addition reaction in silicone industry. This article also mainly introduces the addition reaction between silicon hydrogen bond and carbon carbon double bond.

According to the different catalytic systems, hydrosilylation can be divided into free radical addition mechanism and coordination addition mechanism. Under UV, high temperature γ- Under the conditions of X-ray, peroxide and azoate, the hydrosilylation reaction proceeds according to the free radical addition mechanism; Under the action of transition metal catalysts such as platinum, palladium, rhodium and nickel, it is carried out according to the coordination addition mechanism. Because transition metal catalysts have high activity and selectivity, common hydrosilylation reactions are mainly carried out under the catalysis of transition metal catalysts, among which platinum catalyst is the most widely used transition metal catalyst.

Three components of hydrosilylation reaction

It can be seen from the hydrosilylation reaction formula that hydrosilylation reaction mainly includes compounds containing carbon carbon double bonds, compounds containing silicon hydrogen bonds and platinum catalysts. Among them, compounds containing carbon carbon double bonds can be small organic molecules with carbon carbon double bonds, small organic silicon molecules with carbon carbon double bonds or organic silicon polymers, such as vinyl silicone oil, vinyl silicone rubber and vinyl silicone resin; Compounds containing silicon hydrogen bonds mainly include silicone small molecules containing silicon hydrogen bonds and silicone polymers such as hydrogen containing silicone oil, hydrogen containing silicone resin and hydrogen containing silicone rubber; At present, the most widely used platinum catalyst is karstedt's catalyst diluted with specific diluent. The main component is the complex of platinum and vinyl double head. It has high catalytic activity and fast reaction speed, but it is also easy to be poisoned and inactivated. Therefore, during packaging, transportation and use, it is necessary to avoid the platinum catalyst from contacting nitrogen Organic compounds of phosphorus, sulfur and other elements and ionic compounds containing heavy metals such as tin, lead, mercury, bismuth and arsenic are easy to poisoning and failure of platinum catalyst.

Hydrosilylation can also occur at room temperature. After heating, the reaction speed is very fast, and a large amount of heat will be released with the reaction process. Therefore, when using this reaction for industrial production, we should pay attention to the batching sequence, and the ratio of each component in the formula should also be controlled within a reasonable range to prevent affecting the product performance or accidents. Generally, in addition to the three components of carbon carbon double bond compound, silicon hydrogen bond compound and platinum catalyst, a small amount of polymerization inhibitor will be added in the hydrosilylation reaction. The polymerization inhibitor is mainly used to inhibit the reaction speed of hydrosilylation reaction at room temperature, but under heating conditions, the polymerization inhibitor has little effect on the reaction speed of hydrosilylation reaction.

After understanding the components and application fields of hydrosilylation reaction, for the specific products using hydrosilylation reaction, the performance of the products can be improved by selecting raw materials with different indexes, designing different formulas and adding various types of additives, The reaction speed can be controlled by selecting platinum catalysts with different activities and changing the amount of platinum catalyst, so as to improve the production efficiency and finally make products with excellent performance.