HMS -991

HMS -991 by Gelest (Mitsubishi Chemical) is polymethylhydrosiloxanes. It exhibits the highest compressibility of the silicone fluids, 9.32% at 20,000 psi and the lowest viscosity temperature coefficient, 0.50. This trimethylsiloxy terminated hydride functional homopolymers undergoes three main classes of reactivity: hydrosilylation, dehydrogenative coupling and hydride transfer. It is a versatile low cost hydride transfer reagent with the hydride equivalent weight of 60. The reactions are catalyzed by Pd⁰ or dibutyltin oxide and the choice of reaction conditions lead to chemo selective reduction, e.g. allyl reductions in the presence of ketones and aldehydes. HMS -991 is used as water-proofing agents, reducing agents, components in some foamed silicone systems and in encapsulant applications.