Patent ID: 6437163
Filing Date: 2002-08-20
Classification: A61K,A61Q

Abstract:
A process for preparing polyorganosiloxanes containing (an) arylalkyl function(s), of high purity, by hydrosilylation reaction of a hydrogenopolyorganosiloxane, reagent (SiH), with a monovinylaromatic compound, reagent (Vi) in the presence of a hydrosilylation catalyst, wherein said process comprisescarrying out the hydrosilylation operation at a temperature from 50Â° C. to 150Â° C., in the presence of a solvent (S), which is inert with respect to the reagents, having a boiling point at atmospheric pressure of less than 200Â° C., by simultaneous introduction of the two reagents (Vi) and (SiH) into the reaction medium comprising the solvent (S) and the hydrosilylation catalyst, this introduction being carried out such that the respective amounts of the two reagents (Vi) and (SiH) corresponding to a reagent (Vi)/reagent (SiH) molar ration of more than 0.5 to 1.5, and in that at any moment in the hydrosilylation reaction, the amount of reagent (SiH) present, expressed as the mass of SiH functions (29 g per 1 function), corresponds to less than 2% of the reaction mass, excluding the mass of solvent, and wherein the hydrosilylation operation is followed by an operation for removal of the solvent (S) and any residual reagents (SiH) and (Vi), and/or by a hydrogenation operation, said hydrogenation operation optionally being followed by an operation for removal (or a new operation for removal) of the products other than the polyorganosiloxanes containing (an) arylalkyl function(s).