GB685173A - A process for the manufacture of alkoxy siloxanes - Google Patents

Abstract

Alkoxy-polysiloxanes are made by reacting one or more chlorosilanes of the general formula RnSiCl4-n, wherein R is a saturated aliphatic hydrocarbon radical containing less than 7 carbon atoms or a monocyclic aryl radical, and n has a value from 0.9 to 2.1, with a primary or secondary saturated monohydroxy alcohol in amount of 5 to 90 mol. per cent per gram atom of silicon-bonded chlorine in the chlorosilane, and hydrolysing the alkoxylated chlorosilane or chlorosilane mixture so formed by reacting it with water in amount at least sufficient to hydrolyse all the chlorine atoms but in not more than 10 per cent excess of such amount. Silanes specified are those in which R is methyl, ethyl, propyl, butyl, cyclohexyl, cyclopentyl, phenyl, chlorophenyl, tolyl or xylol, and mixtures of SiCl4, RSiCl3, R2SiCl2 and R3SiCl. Alcohols specified are methyl, ethyl, isopropyl, secondary butyl, n-butyl, n-amyl, n-stearyl, cyclohexyl and cyclopentyl alcohols. The reactions are usually effected at 20-30 DEG C. and may be executed in a solvent inert to the chlorosilane(s), e.g. toluene, xylene, benzene, petroleum ether, ether, and tertiary amines. After addition of water, the reactants are preferably heated under reflux, any volatile matter being removed. If desired, any residual acidity may be removed from the products by treatment with sodium bicarbonate. In examples, alkoxy-polysiloxanes are obtained by hydrolysis of reaction products of (1) isopropanol with a mixture of phenyltrichloro- and dimethyldichloro-silanes; (2, 3) isopropanol with a mixture of phenylmethyldichloro-, phenyltrichloro- and methyltrichloro-silanes; (4, 5) isopropanol with a mixture of phenylmethyldichloro- and phenyltrichloro-silanes; and (6) ethanol with a mixture of dibutyldichloro - and chlorophenyltrichloro - silanes. The products find use as intermediates in the preparation of siloxane resins.