PRODUCTION OF CYCLIC POLYSILOXANE

摘要

PURPOSE:To efficiently and stably obtain a cyclic polysiloxane on an industrial scale in a high yield by keeping the amount of low-boiling point impurities in a Sin-containing cyclic polysiloxane as a raw material below a specified value in the case of hydrosilyl reaction with a platinum catalyst. CONSTITUTION:Firstly, the content of the low-boiling point impurities in a SiH-containing polysiloxane of the formula [R is a univalent hydrocarbon free from an aliphatic multiple bond; (m) is a positive integer; (n) is 0 or a positive integer; (m)+(n)=4-8], (e.g. heptamethylcyclotetrasiloxane) as a raw material is reduced to <=1wt.% preferably by heating in the presence of a platinum catalyst consisting of an isopropyl alcohol solution of platinic chloride. Subsequently, the treated compound is subjected to hydrosilyl reaction with an aliphatic multiple bond-containing compound (e.g. ethylene) in the presence of the platinum catalyst preferably in an inert gas atmosphere to obtain the objective compound. Further, the reaction is preferably carried out at 30-100 deg.C and usually with in 10hr.