Polymethylhydrosiloxane

Polymethylhydrosiloxane

Names
Other names Methyl hydrogen siloxane; Poly(methyl siloxane); Poly(methylhydrosiloxane); Polysilicone 4
Identifiers
CAS Number	9004-73-3 Y
Abbreviations	PMHS
ChemSpider	none
ECHA InfoCard	100.119.568
Properties
Chemical formula	(CH3(H)SiO)n
Molar mass	variable
Density	1.06 g/cm3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

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 dimethylsiloxane and methylhydrosiloxane, and trimethylsilyl terminated materials.

This material is prepared by the hydrolysis of methyldichlorosilane:

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: