METHOD OF PRODUCING LINEAR POLYDIMETHYLSILOXANES WITH TERMINAL HYDROXYL GROUPS VIA POLYCONDENSATION OF DIMETHYLDIALKOXYSILANES IN ACTIVE MEDIUM Russian patent published in 2012 - IPC C08G77/06 C08G77/16 

FIELD: chemistry.

SUBSTANCE: disclosed is a method of producing linear polydimethylsiloxanes with terminal hydroxyl groups, involving polycondensation of dimethyldialkoxysilane selected from dimethyldialkoxysilanes of general formula (CH₃)₂Si(OAlk)₂ (I), where Alk denotes an alkyl group from C₁ to C₄, wherein the polycondensation process is carried out in an active medium which is an anhydrous carboxylic acid selected from: formic, acetic, propionic, isobutyric, trimethylacetic acid, with subsequent removal of volatile components. Molar ratio of dimethyldialkoxysilane to carboxylic acid ranges from 1:3 to 1:10. The polycondensation process in the active medium is carried out at temperature ranging from 20°C to boiling point of the reaction mixture, and removal of volatile components is carried out in a vacuum at temperature ranging from 20°C to 150°C. Depending on conditions for polycondensation of the initial dimethyldialkoxysilane, molecular weight of the reaction product ranges from 3500 to 70000.

EFFECT: possibility of regulating molecular weight of linear polydimethylsiloxanes with terminal hydroxyl groups, absence of residual alkoxy groups and cyclic components in the product, low polydispersity of the product and environmental friendliness of the process.

11 cl, 3 dwg, 1 tbl, 6 ex