The silicon-hydrogen addition reaction refers to the addition reaction between an organosilicon compound containing silicon-hydrogen bonds and a compound containing unsaturated bonds under certain conditions. It is the main form of silicon-carbon bond formation, and is the most basic and most basic in organosilicon chemistry. One of the important types of reactions. The unsaturated bond may be a carbon-carbon double bond, a carbon-carbon triple bond, a carbon-oxygen double bond, a carbon-nitrogen double bond, and the like. Among them, the addition reaction between the silicon-hydrogen bond and the carbon-carbon double bond is the most common silicon-hydrogen addition reaction in the silicone industry, and it is the core reaction of many addition-formed silicone products.

For the hydrosilylation reaction, in addition to the hydrosilylation compound and the unsaturated compound, the catalyst is an indispensable component, which plays a role in accelerating the reaction speed, shortening the reaction time and lowering the reaction temperature. The catalysts for the hydrosilylation reaction are mainly compounds of platinum, palladium, nickel and rhodium and their complexes of the transition metal elements of group ⅧB in the periodic table. Among them, the platinum catalyst has the highest catalytic activity and is the most widely used.
Platinum catalysts used to catalyze the hydrosilylation reaction are mainly divided into homogeneous catalysts and heterogeneous catalysts. Among them, the homogeneous catalyst and the reactants are in the same phase, and there is no phase interface. In the hydrosilylation reaction, the homogeneous catalyst generally refers to a liquid catalyst.
There are three main homogeneous platinum catalysts: The first is to dissolve chloroplatinic acid (H2PtCl6 6H2O) in organic solvents such as ethanol, isopropanol, and tetrahydrofuran, and let them interact to form a complex, called "Speier catalyst". This kind of catalyst is simple, quick and easy to use; the second type of platinum catalyst is a complex of platinum and vinyl with double caps, called Karstedt's catalyst, which has high reaction activity and can be stored stably , And good compatibility with various types of polysiloxanes, it is the most widely used catalyst in addition type silicone release agents; the third type of platinum catalyst is formed by chloroplatinic acid in addition to some other unsaturated compounds The complexes also form complexes with ketones, cyclopentadiene, esters, alcohols, crown ethers, crown ethers containing heteroatoms and polysiloxanes, which are used as catalysts.

Homogeneous platinum catalysts have high activity and reaction selectivity, but because they are in the same phase as the reactants, they are difficult to separate after the reaction is completed and cannot be reused. Therefore, the cost is high, and heavy metal ion pollution may be caused at the same time. Therefore, researchers have solid-supported homogeneous catalysts into heterogeneous catalysts. The so-called solid support of homogeneous catalyst is to combine homogeneous catalyst with solid support by physical or chemical methods to form a special catalyst. The heterogeneous platinum catalyst and the reactants are in different phases, and the common form is that the solid catalyst catalyzes the hydrosilylation reaction of the liquid mixed reactant.

The heterogeneous catalysts for the hydrosilylation reaction are mainly divided into two types, the traditional heterogeneous platinum catalyst and the polymer metal complex catalyst. Among them, the traditional heterogeneous catalyst is formed by adsorbing transition metals on inorganic particles such as carbon black and alumina. This type of catalyst has high stability and can be recycled and reused, but its catalytic activity and selectivity are low. Need higher temperature and pressure. The polymer metal complex catalyst is composed of a polymer carrier, a ligand bonded to the carrier, and a transition metal. In general, although the heterogeneous catalyst has the advantages of high stability and recyclability, its application is subject to certain restrictions due to its low activity and selectivity, and the complicated preparation process, which reduces its catalytic activity when used again. limit.

There are many types and forms of platinum catalysts. Therefore, in the application process, a suitable platinum catalyst must be selected according to the characteristics of the reaction system to achieve the best catalytic effect.