process for the production of octaphenylcyclotetrasiloxan and sym - tetramethyltetraphenylcyclotetrasiloxan

摘要

A process for the production of octaphenylcyclotetrasiloxane (I) comprises: (a) reacting a dihalodiphenylsilane of formula (C6H5)2Si(X)2 (2) with an alcohol of formula ROH (3) to produce a dialkyloxydiphenylsilane of formula (C6H5)2Si(OR)2 (4). X = a halogen selected from Cl, Br and I; R = a 1-10C monovalent hydrocarbon radical; (b) mixing (4) with a solvent to form a mixture. (I) is sparingly soluble in the solvent; (c) adding to the mixture a base catalyst and water to hydrolyse (4). A base concentration of 1-5,000 ppm is provided by the base catalyst; and (d) refluxing the mixture to precipitate (I) from the solvent. Also claimed is a similar process for producing symm-tetramethyltetraphenylcyclotetrasiloxane (5), except that: in (a) a compound of formula (CH3)(C6H5)Si(X)2 (6) is used in place of (2) and reaction proceeds via an intermediate of formula (CH3)(C6H5)Si(OR)2 (7) c.f. (4). (7) is then mixed with solvent in (b) and subsequently hydrolysed in (c).