Polymethylhydrosiloxane

Details:

Polymethylhydrosiloxane (PMHS) is a polymer with the general structure -(CH3(H)Si-O)-. It is used in organic chemistry as a mild and stable reducing agent easily transferring hydrides to metal centers.A variety of related materials are available under the following CAS registry numbers 9004-73-3, 16066-09-4, 63148-57-2, 178873-19-3. These include the tetramer ((MeSiHO)4), copolymers of dimethysiloxane and methylhydrosiloxane, and trimethylsilyl terminated materials.
This material is prepared by the hydrolysis of methyldichlorosilane:
n MeSiHCl2 + n H2O → (MeSiHO)n + 2n HCl
The related polymer polydimethylsiloxane (PDMS) is made similarly, but lacking Si-H bonds, it exhibits no reducing properties.
Illustrative of its use, PMHS is used for in situ conversion of tributyltin oxide to tributyltin hydride:
2"(MeSiH)" + (Bu3Sn)2O → "(Me2Si2O" + 2 Bu3SnH

Polymethylhydrosiloxane
Names
Other names
Methyl hydrogen siloxane; Poly(methyl siloxane); Poly(methylhydrosiloxane); Polysilicone 4
Properties
Chemical formula (CH3(H)SiO)n

Product Name:Polymethylhydrosiloxane
Synonyms:METHYLHYDROGENSILOXAN POLYMER;PMHS;POLYMETHYLHYDROSILOXANES;POLYMETHYLHYDROSILOXANE, TRIMETHYLSILYL TERMINATED;Methyl hydrogen polysiloxane~PMHS;METHYLPOLYSILOXANEOIL;Poly[oxy(methylsilylene)];Polymethylhydrosiloxane
CAS:9004-73-3
MF:(CH3)3SiO[(CH3)HSiO] nSi(CH3)
MW:0
EINECS:
bp >177 °C(lit.)
density 1.006 g/mL at 25 °C(lit.)
refractive index n20/D 1.398
Fp 250 °F
Water Solubility PRACTICALLY INSOLUBLE
Sensitive Moisture Sensitive