For hydrogen silane addition reaction, in addition to hydrogen silane and unsaturated compounds, catalyst is an indispensable component, which plays a role in accelerating the reaction speed, shortening the reaction time and reducing the reaction temperature. The catalysts for the addition reaction of hydrogen silane are mainly the compounds and complexes of group ⅷ B transition metals in the periodic table, such as platinum, palladium, nickel and rhodium, among which platinum catalyst has the highest catalytic activity and is most widely used.
The platinum catalysts used to catalyze the addition reaction of hydrogen silane are mainly divided into homogeneous catalysts and heterogeneous catalysts. Among them, homogeneous catalyst and reactant are in the same phase, no phase interface exists, in the addition reaction of hydrogen silicon, homogeneous catalyst generally refers to liquid catalyst.
There are three kinds of homogeneous platinum catalysts. The first is to dissolve chloroplatinic acid (H2PTCl6-6H2O) into organic solvents such as ethanol, isopropyl alcohol and tetrahydrofuran, and let them interact to form complexes, which is called "Speier catalyst". This catalyst is simple, quick and easy to make and use. The second type of platinum catalyst is platinum and vinyl double head complex, called Karstedt's catalyst (Karstedt's catalyst), its reaction activity is high, stable storage, and good compatibility with various types of polysiloxane, is the most widely used catalyst in the addition of silicone release agent; The third type of platinum catalyst is that in addition to forming complexes with other unsaturated compounds, chloroplatinic acid also forms complexes with ketones, cyclopentadiene, esters, alcohols, crown ethers, crown ethers containing heteroatoms and polysiloxane, which are used as catalysts.