The hydrolytic polycondensation of diethoxydimethylsilane and hexamethyldisiloxane in an active medium in the presence of a catalytic amount of chlorotrimethylsilane has been studied. It is shown that this method allows for the selective synthesis of low-molecular-weight oligodimethylsiloxanes which do not contain residual reactive groups. The ratio of the reagents and the catalyst amount serve as effective tools for controlling the length of the resulting oligomers and the process duration.

A method for the synthesis of linear oligomethylphenylpentasiloxanes with terminal trimethylsilyl and methyldiphenylsilyl groups in one step by the alkaline hydrolysis of diethoxy(methyl)phenylsilane and subsequent interaction of sodium trimethyltriphenyltrisiloxanediolate with chlorotrimethylsilane or chloro(methyl)diphenylsilane has been studied.

A method for the directed synthesis of hexamethyltrisiloxanediol and 1,1,3,3,5,5,7-heptamethyl-7-phenylcyclotetrasiloxane from sodium hexamethyltrisiloxanediolate in 90% and 55% yields, respectively, is suggested.

The polycondensation of diethoxy(methyl)phenylsilane in an active medium in the presence of acetyl chloride or cation exchanger Purolite CT 175 has been studied, and their effect on the rate and selectivity of the process has been evaluated. It is shown that the use of the sulfonic cation exchanger allows for achieving 100% yields of methylphenylcyclosiloxanes.

The process of hydrolytic polycondensation of diethoxymethylsilane in water under pressure was investigated without the use of organic solvents in non-catalytic conditions and in carbonic acid. It is demonstrated that in both cases the process of the formation of methylsiloxane polymers proceeds with 100% conversion of the monomer and complete preservation of hydrosilyl groups. The conditions for the selective production of linear products were found.

The hydrosilylation of polyallylcarbosilane dendrimers with hydride-containing six- and eight-membered dimethylcyclosiloxanes affords a series of hybrid carbosilane–siloxane dendrimers featuring different densities of the surface cyclosiloxane layers, while retaining all other molecular parameters. The main physicochemical constants of the resulting dendrimers are defined. The possibility of functionalization of these dendrimers by the opening of cyclosiloxane structural moieties in the external shell is demonstrated by the example of the zero-generation dendrimer bearing heptamethylcyclotetrasiloxane terminal groups.

The 1,5-disodiumoxyhexamethyltrisiloxane has been isolated in high yield with a purity of up to 98%, by simple interaction of dimethylsiloxanes with sodium hydroxide. The reasons of high selectivity of the reaction towards 1,5-disodiumoxyhexamethyltrisiloxane were analyzed. It was found that variation of reaction time, type of dimethylsiloxane precursor and ratio between sodium hydroxide and dimethylsiloxanes in wide range led to the materialization of most part of used sodium hydroxide in 1,5-disodiumoxyhexamethyltrisiloxane. Its fast crystallization and precipitation from the homogeneous reaction media were found to be the main reason of the high selectivity of the reaction towards 1,5-disodiumoxyhexamethyltrisiloxane. The crystalline structure of 1,5-disodiumoxyhexamethyltrisiloxane was determined and its packaging peculiarities were discussed and illustrated.

The process of condensation of dimethyldiethoxysilane in the active medium in a presence of acetyl chloride, trifluoroacetic acid, and sulfocationites has been investigated. Their impact on the rate and selectivity of the process has been estimated. The prospects of the application of sulfocationites for the polycondensation of dimethyldiethoxysilane in anhydrous acetic acid with an 99% yield have been demonstrated.