Patent ID: 7741504
Filing Date: 2010-06-22
Classification: C07F

Abstract:
1. A method for preparing an ω-haloalkyl dialkylhalosilane of formula (I): by reacting a silane of formula (II): with an alkene halide of formula (III): in the presence of a catalytically effective amount of a platinum metal hydrosilylation catalyst, wherein said platinum metal is selected from the group consisting of platinum, iridium, palladium, rhodium, ruthenium and osmium, wherein, in the above formulas: the symbol Hal represents a halogen atom selected from the group consisting of chlorine, bromine and iodine, the symbols R represents an integer between 2 and 10, inclusive, said process comprising distilling the reaction mixture at the end of the hydrosilylation reaction and separating the product of formula (I) from the reaction mixture, wherein said distillation forms a liquid residue comprising the product of formula (I) that was not separated by distillation, by-products and the platinum metal catalyst, said process further comprising recovering the catalytic metal from said residue, wherein said method of recovering the catalytic metal from said residue comprises: 1) performing the controlled hydrolysis of the residue resulting from distillation of the reaction mixture containing the catalytic platinum metal by the addition of water wherein the rate of introduction of the water is controlled to avoid any accumulation of water in the medium so that the H-Hal acid formed at each moment is not dissolved in the aqueous phase, said metal being in its original form as catalyst or in a converted form, wherein said controlled hydrolysis: a) reacts the Si-Hal functions of the product of formula (I) present in the residue with water, b) releases the halogen-containing acid, H-Hal, formed in the hydrolysis essentially in the gaseous state, and c) the aqueous medium present after the completion of the addition of water containing the catalytic metal has a content of hydrolyzable halide Si-Hal≦2%, expressed by weight of Hal; and, 2) recovering the catalytic platinum metal without the use of any adsorbent solid and using ordinary apparatus that does not need to be acid-resistant.