METHOD OF PRODUCING LINEAR POLY(METHYL)(HYDRIDE)SILOXANES WITH A GIVEN AVERAGE LENGTH OF A SILOXANE CHAIN Russian patent published in 2020 - IPC C08G77/06 C08G77/16 C08G77/18 

FIELD: chemistry.

SUBSTANCE: invention relates to chemistry and technology of producing linear poly(organo)(hydride)siloxanes. Disclosed is a method of producing linear poly(methyl)(hydride)siloxanes [(CH₃)₃SiO_0.5]₂[CH₃(H)SiO]_m with given average length of siloxane chain (m=5÷60) by acid-hydrolytic copolyukondensation of a mixture of trimethyl-[(CH₃)₃SiOR] and (methyl)(hydride)di-[CH₃(H)Si(OR)₂] alkoxysilanes, where R=CH₃, C₂H_5, with output of linear polysiloxanes of not less than 95 wt%. Process is carried out with acetic acid taken in the calculated amount required for complete hydrolysis and condensation of a mixture of mono- and difunctional alkoxy silanes in the presence of catalyst – concentrated 36 % hydrochloric acid taken in amount not exceeding 0.03 wt% in terms of HCl. Process is carried out at temperature of 80÷90 °C for 2 hours with subsequent distillation of ester, alcohol and hydrogen chloride for 1 hour to increase pH of product of not less than 6.5 and completion of distillation of volatile products in rotary evaporator at temperature of not more than 70 °C under vacuum for 1 hour.

EFFECT: disclosed is a method of producing linear poly(methyl)(hydride)siloxanes with a given average length of a siloxane chain.

1 cl, 3 ex