Patent ID: 7645894
Filing Date: 2010-01-12
Classification: C07F,C08G

Abstract:
1. A continuous process for making cyclic dimethylsiloxane oligomers which comprises continuously feeding a mixture of methyl bromide and dimethyl ether within a direct reaction zone containing a dynamic bed of activated direct synthesis quality silicon metal particles associated with direct synthesis quality copper catalyst and promoter at an elevated temperature between 200° C. and 400° C., which bed is rendered dynamic by either gas fluidization or by stirring in the form of a slurry in an inert liquid solvent having a boiling point greater than said elevated temperature, to effect a reaction between the methyl bromide, dimethyl ether and silicon to produce cyclic dimethylsiloxane oligomers such that there is at least one complete silicon metal bed turnover during the continuous process, and the proportion of dimethylsiloxanes inclusive of cyclic dimethylsiloxane oligomers produced in said bed is greater than 75 mole % of the methylsiloxanes produced from said reaction, continuously recovering dimethylsiloxanes inclusive of such cyclic dimethylsiloxane oligomers from the direct reaction zone, and recycling methyl bromide as formed in the direct reaction zone to the feed of such mixture.