A continuous economic and environmentally friendly process for preparation of polyorganosiloxanes from organochlorosilanes with complete recycling of the gaseous HCl without accumulation of contaminated waste water

摘要

Continuous process for preparation of siloxanes from silanes, SiCl4 and their mixtures comprises: (A) reaction with HCl to give oligomer with formation of gaseous HCl; (B) conversion of oligomer to siloxane with excess of HCl, separation of siloxanes and HCl, feeding of the separated HCl-water to step A; and (C) neutralization of siloxane, separation of siloxane/water mixture, and feeding of HCl-water mixture to step B. A continuous process for preparation of siloxanes, that are built up from at least two units selected from formulae (I)-(IV), from silanes of formulae (V)-(VII), SiCl4 and their mixtures, comprises: (A) the reactants are reacted with HCl (1) in a first step to give an oligomer with formation of gaseous HCl; (B) the oligomer is converted to a siloxane, using an excess of HCl (2) and is fed to the circuit, the mixture of siloxanes and HCl (1) is separated in a separator,and the separated HCl-water is fed to the first step; and (C) the siloxane is neutralized, mixed with a water excess, the siloxane/water mixture is separated on a separator, and the separated HCl-water is fed to the second step (B). ((R1)3 SiO1 / 2) (I) ((R1)2 SiO2 / 2) (II) ((R1) SiO3 / 2) (III) (SiO4 / 2) (IV) (R)2SiCl2 (V) (R)3SiCl (VI) RSiCl3 (VII) R = 1-6C alkyl or 6-12C aryl, (preferably Me); and R1 = R or OH.