Separation of chlorosilanes by liquid extraction

摘要

This invention relates to a method of separating close-boiling chlorosilanes from mixtures by employing the technique of liquid extraction with sulfolane and a hydrocarbon compound as co-solvents. The hydrocarbon compound employed is substantially immiscible in sulfolane and is present in sufficient amounts so that two liquid phases are formed, one being suloflane-rich and the other being hydrocarbon-rich. The mixture of chlorosilanes is intimately mixed with the two solvents and allowed to partition between the two phases. The preferred liquid extraction procedure is where the sulfolane and hydrocarbon solvent are in a countercurrent relationship within an extraction tower. Experimentally determined selectivity coefficients show that mixtures of (1) dimethyldichlorosilane and methyltrichlorosilane, (2) phenylmethyldichlorosilane and phenyltrichlorosilane, and (3) trimethylchlorosilane and tetrachlorosilane can be successfully separated by the techniques of this invention.