Thermally stable polyfluorinated monoalkoxysilanetriols and dialkoxydisiloxanetetrols.

Abstract

The reaction of the polyfluorinated lithium triarylmethanolates Ar3COLi (Ar = C6F5, 3,5-(CF3)2C6H3) with SiCl4 provided the monosubstituted products Ar3COSiCl3 (1a, Ar = C6F5; 1b, Ar = 3,5-(CF3)2C6H3). The hydrolysis of 1a and 1b produced the silanetriols Ar3COSi(OH)3 (2a, Ar = C6F5; 2b, Ar = 3,5-(CF3)2C6H3) without the aid of an HCl scavenger. The reaction of two equivalents of Ar3COLi (Ar = C6F5, 3,5-(CF3)2C6H3) with (Cl3Si)2O afforded the disubstituted products [(C6F5)3COSiCl2]2O (3a) and {[(3,5-(CF3)2C6H3)3CO]SiCl2}2O (3b), the hydrolysis of which gave the corresponding disiloxanetetraols [(C6F5)3COSi(OH)2]2O (4a) and [(3,5-(CF3)2C6H3)3COSi(OH)2]2O (4b). At high concentrations in the presence of HCl, 2b undergoes controlled condensation to yield 4b. In the solid-state, 2a, 4a and 4b are mainly associated by hydrogen bonds of the type SiO-H⋯O(H)Si whereas the competing SiO-H⋯O(C)Si type was not observed.