Lanzhou Greenchem ILs (Center for Greenchemistry and catalysis), LICP, CAS. Ionic Liquids

The process of hydrosilylation of a polydimethylsiloxane can be represented as:

The hydrosilylation of the CLC double bond with silanefunctionalised polydimethylsiloxanes is a widely applied reaction in industrial synthesis for the production of organosilicon compounds on a technical scale. Degussa have used ionic liquids as a means of catalyst heterogenisation: the catalyst (ionic) is dissolved in the ionic liquid, from which there is no significant leaching, but in which the product is insoluble. Their aim was the synthesis of polyethersiloxanes, an important class of surface active compounds which find use in a broad range of industrial applications. The experimental procedure is rather simple, and can be described as a one-pot biphasic synthesis.

The hydrophobicity of the organosilicon products increases with increasing chain length and decreasing silane-functionalisation of the polydimethylsiloxane. The polyethers are more hydrophobic, the higher the content of propylene oxide. The ionic liquid phase separates more easily from the organosilicon products the more hydrophobic they are.