Synthesis of 1,1,3,3,5,5-Hexamethyl-7,7-diorganocyclotetrasiloxanes and Its Copolymers

Abstract

This paper reports a method for the synthesis of 1,1,3,3,5,5-hexamethyl-7,7-diorganocyclotetrasiloxanes by the interaction of 1,5-disodiumoxyhexamethylsiloxane with dichlorodiorganosilanes such as methyl-, methylvinyl-, methylphenyl-, diphenyl- and diethyl dichlorosilanes. Depending on the reaction conditions, the preparative yield of the target cyclotetrasiloxanes is 55–75%. Along with mixed cyclotetrasiloxanes, the proposed method leads to the formation of polymers with regular alternation of diorganosylil and dimethylsylil units. For example, in the case of dichlorodiethylsilane, 70% content of linear poly(diethyl)dimethylsiloxanes with regular alternation of units can be achieved in the reaction product. Using 7,7-diethyl-1,1,3,3,5,5-hexamethylcyclotetrasiloxane as an example, the prospects of the mixed cycle in copolymer preparation in comparison with the copolymerization of octamethyl- and octaethylcyclotetrasiloxanes are shown.

Ring-Opening Polymerization (ROP) and Catalytic Rearrangement as a Way to Obtain Siloxane Mono- and Telechelics, as Well as Well-Organized Branching Centers: History and Prospects

“…This problem can be solved using mixed dimethylcyclotetrasiloxanes, the synthesis of which is considered in the work Talalaeva E.V. et al [146].…”

“…Polymers 2022, 14, x FOR PEER REVIEW 23 of 37 should be noted that the substituents at the silicon atom strongly affect the rate of polymerization of cyclosiloxanes; as a result, it is difficult to obtain copolymers by polymerizing a mixture of cyclosiloxanes with different groups at the silicon atom. This problem can be solved using mixed dimethylcyclotetrasiloxanes, the synthesis of which is considered in the work Talalaeva E. V. et al [146].…”