The Influence of HCl Concentration on the Rate of the Hydrolysis-Condensation Reaction of Phenyltrichlorosilane and the Yield of (Tetrahydroxy)(Tetraphenyl)Cyclotetrasiloxanes, Synthesis of All Its Geometrical Isomers and Thermal Self-Condensation of Them under "Pseudo"-Equilibrium Conditions.

The rate of hydrolysis-condensation reaction of phenyltrichlorosilane in water-acetone solutions and the product yields were shown to significantly depend on the concentration of HCl (CHCl) in the solutions. The main product of the reaction was all-cis-(tetrahydroxy)(tetraphenyl)cyclotetrasiloxane. This was different from the earlier published results of analogous reactions of m-tolylSiCl3, m-ClPhSiCl3, and α-naphtylSiCl, in which some products of other types were formed. For example, trans-1,1,3,3-tetrahydroxy-1,3-di-α-naphtyldisiloxane was obtained in the case of α-naphtylSiCl3. All-cis-(tetrahydroxy)(tetraphenyl)cyclotetrasiloxane was treated in acetone with HCl to give the other three geometric isomers (cis-cis-trans-, cis-trans-, and all-trans-). The thermal self-condensation of these four isomers under "pseudo"-equilibrium conditions (under atmospheric pressure) was investigated in different solvents, in quartz or molybdenum glass flasks. The compositions of the products were monitored by APCI-MS and 29Si NMR spectroscopy. It was shown that all-cis- and cis-cis-trans-isomers in toluene or anisole mostly gave the cage-like Ph-T8,10,12,14 and uncompleted cage-like Ph-T10,12OSi(HO)Ph compounds. In contrast to these two isomers, the cis-trans-isomer in toluene mainly formed dimers with the loss of one or two molecules of water. However, in acetonitrile, significant amounts of Ph-T10,12 and Ph-T10,12OSi(HO)Ph species were formed along with the dimers. All-trans-isomer did not enter into the reaction at all.

A Study of the Influence of the HCl Concentration on the Composition and Structure of (Hydroxy)Arylsiloxanes from the Hydrolysis-Condensation Reaction of Aryltrichlorosilanes.

The hydrolysis-condensation reactions of m-tolyl, m-chlorophenyl, and α-naphtyl-trichlorsilanes, (1, 2, and 3, respectively) in water-acetone solutions were examined for how they were influenced by the change in the concentration of HCl (CHCl). The composition of the products was monitored by 29Si NMR spectroscopy and atmospheric pressure chemical ionization mass spectrometry (APCI-MS). The acidity of the medium was shown to affect the yields of the products, and so, what products were formed. For 3, e.g., APCI-MS showed peaks of α-naphtyl-T8 and α-naphtyl-T10 as the most abundant in the spectra taken after 48 and 240 h for the reaction conducted at CHCl = 0.037 mol L-1. Unlike this, at CHCl = 0.15 mol L-1, those peaks were of [α-naphtyl(HO)2SiO]2(α-naphtyl)(HO)Si and/or [α-naphtyl(HO)Si]3, [α-naphtyl(HO)Si]4,5, and α-naphtyl-T8 after 192 h. However, at both CHCl values, the main product (and an intermediate) after 24 h was trans-1,1,3,3-tetrahydroxy-1,3-di-α-naphtyldisiloxane. It was isolated and its structure established by 1H-, 29Si-NMR, and X-ray powder diffraction.

A Study of the Polycondensation of (Tetrahydroxy)(Tetraaryl)Cyclotetrasiloxanes under Equilibrium and Non-Equilibrium Conditions in the Presence and Absence of Montmorillonite.

Oligo- and polycyclosiloxanes were obtained by the polycondensation of (tetrahydroxy)(tetraaryl)cyclotetrasiloxanes in equilibrium and non-equilibrium conditions in the presence and absence of montmorillonite (MMT). Their composition and the structures of their components were investigated by infrared (IR) spectroscopy, 29Si nuclear magnetic resonance (NMR) spectroscopy, atmospheric pressure chemical ionization (APCI) mass spectrometry, powder X-ray diffraction (XRD), and gel-penetrating chromatography (GPC). Also, a comparison of polymers formed in the presence of MMT and via anionic polymerization was performed showing differences in their structures.