METHOD FOR PRODUCING HIGH-PURITY OCTAMETHYLCYCLOTETRASILOXANE AND DECAMETHYLCYCLOPENTASILOXANE BY SEPARATING MIXTURE OF METHYLCYCLOSILOXANE VAPOURS Russian patent published in 2024 - IPC C07F7/21 C07F7/08 

FIELD: high-purity methylcyclosiloxanes.

SUBSTANCE: invention relates to methods for producing high-purity methylcyclosiloxanes. A method has been proposed for the production of high-purity octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) by separating a mixture of methylcyclosiloxane vapours. In a distillation column for the primary separation of methylcyclosiloxanes, made with a cube and operating at reduced pressure, a stream containing decamethylcyclopentasiloxane is isolated as a side selection, which is sent to the high-purity decamethylcyclopentasiloxane separation column, operating at reduced pressure. The distillates of the primary column and the decamethylcyclopentasiloxane separation column, which are a mixture of hexamethylcyclotrisiloxane (D3) and octamethylcyclotetrasiloxane, are sent to a distillation column for the separation of high-purity octamethylcyclotetrasiloxane, operating at reduced pressure. In this case, octamethylcyclotetrasiloxane is isolated as a bottom selection; a mixture of hexamethylcyclotetrasiloxane and octamethylcyclotetrasiloxane is obtained as a distillate containing octamethylcyclotetrasiloxane in the amount necessary to prevent the formation of the solid phase at ambient temperature.

EFFECT: use of the proposed method ensures the production of high-purity D4 and D5 while simultaneously reducing total energy costs by 31% compared to known methods; at the same time, the risk of D3 solidifying in the process equipment is eliminated.

17 cl, 2 dwg, 1 tbl, 5 ex