Cascade synthesis of polyorganosiloxanes in an organodichlorosilane—acetone—carbamide non-aqueous system

Abstract

Нydrolytic polycondensation of organochlorosilanes (OCS) RR´SiCl₂, where R,R´= Me, Et, C₂H₃, and H, in an acetone—carbamide non-aqueous system was studied. It was found by GLC, GPC, ²⁹Si NMR spectroscopy, mass spectrometry, and elemental analysis that linear and cyclic oligoorganosiloxanes were formed in a quantitative yield as a result of hydrolysis. The mechanism of the process includes conjugate mutually dependent reactions: (i) generation of water via dehydrocondensation of acetone and carbamide involving HCl and (ii) hydrolysis of OCS to form HCl. This determines the cascade character of the overall process. The hydrolysis of OCS in the system studied develops with autoacceleration like branched cascade processes because of peculiarities of stoichiometry of the dehydrocondensation of acetone and carbamide.