Process for making alpha,omega-siloxanediols
AssigneeSWS Silicones Corporation
InventorsRichard N. Lewis, Eugene R. Martin
Life of this patent
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Abstract
Alpha,omega-siloxanediols are prepared from siloxanes by a two-step process. In the first step, the siloxane is converted to a linear alpha,omega-diacyloxysiloxane by heating with an acid anhydride and a carboxylic acid in the presence of acid clay. The diacyloxysiloxane is hydrolyzed to the siloxanediol by heating with an aqueous solution of a weak base.
Claims8
A process of making alpha,omega-siloxanediols of the formula HO(R.sub.2 SiO).sub.n H, in which at least 50 percent of the R groups are methyl and the remaining R groups are selected from the class consisting of vinyl and phenyl and n is a number of from 3 to 25, which comprises heating an alpha,omega-diacyloxysiloxane with an aqueous solution having a pH of from 8 to 11 to a temperature of at least 50.degree. C.
A process for making alpha,omega-diacyloxysiloxanes which comprises heating a siloxane with an acid anhydride having from 4 to 8 carbon atoms in the presence of a carboxylic acid having from 2 to 4 carbon atoms and acid clay for at least 1 hour at a temperature of from 120.degree. C to 150.degree. C.
Dependencies are inferred from the claim text.