Process for co-alkoxylation of halosilanes and separation of the

Abstract

A process for converting a mixture of at least two different halosilanes having the general formula, R.sub.n SiX.sub.4-n, which are difficult to separate, to at least two different alkoxysilanes having the formula, R.sub.n Si(OR').sub.4-n, where R and R' are saturated or unsaturated alkyl groups of 1 to about 8 carbon atoms or aromatic; X is halogen; and n is 0-3; and separating the alkoxysilanes, is disclosed. The co-alkoxylation of the halosilanes is carried out by charging a reboiler equipped with a reflux column with an alkoxylating agent, such as, an aliphatic alcohol, and, optionally, at least one of the halosilanes being alkoxylated; feeding at least two halosilanes to be co-alkoxylated into the upper section of the column; introducing the alkoxylating agent, such as, an aliphatic alcohol, into the upper section of the column to react with the halosilanes in a reaction zone in the column and thereby form alkoxysilanes and hydrogen halide; removing the hydrogen halide; collecting at least two alkoxysilanes formed in the column and separating the alkoxysilanes. In one preferred embodiment, the alkoxysilanes are separated and collected at two different points in the column in a distillation zone below the rection zone. Two halosilanes, which are co-methoxylated and thereafter separated, are dimethyldichlorosilane and methyltrichlorosilane which form dimethyldimethoxysilane and methyltrimethoxysilane, respectively, when heated in the presence of the alkoxylating agent, methanol.