Prepn. of methyl:alkoxy:oligo(di:silyl)-siloxane cpds. - by two stage alkoxylation of distn. residue from methyl:chlorosilane synthesis or di:silane(s) from residue

摘要

In prepn. of methylalkoxyoligo(disilyl)-siloxanes (I) by alkoxylation of distn. residues from synthesis of methylchlorosilane, contg. disilanes, or of the disilanes, followed by conversion of residual SiCl, (a) the distn. residue or the disilanes is reacted with at least 65 wt.% of the amt. of 1-8C aliphatic alcohols needed for complete con-alkoxylation, under reflux, (b) excess alcohol is removed, and (c) reaction is continued with at least the amt. of 1-8C aliphatic alcohol needed for complete alkoxylation, and with at least the amt. of CaCO3 needed for neutralisation of the HCl formed from the residual SiCl. USE/ADVANTAGE - (I) are used as hydrophobising agents in building, and are raw materials for organo-Si cpds. Substitution of the SiCl is quantitative, with no attack on the Si-Si bond and no formation of polysiloxanes. The prods. have almost no residual Cl and 5-50 wt.% of alkoxy gps., and may be solvent-free or in soln. in organic solvents.