Method for the preparation of diorganopolysiloxanes
AssigneeDow Corning Toray Silicone Co., Ltd.
InventorTadashi Okawa
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Abstract
A method for the high-purity synthesis of a diorganopolysiloxane having a functional group at only one molecular chain terminal, that is characterized by the preliminary silylation with a silylating agent of the silanol group-containing impurity present in the cyclic trisiloxane, and that is characterized by preliminarily converting the silanol group-containing impurity in the cyclic trisiloxane into a lithiated material by lithiation with an organolithium compound and then silylating this lithiated material using a silylating agent that contains silicon-bonded halogen.
Claims4
A method for the preparation of a diorganopolysiloxane with the formula
- R(R.sub.2 SiO).sub.p B
- in which R is a monovalent hydrocarbon group, p is an integer with a value of at least 1, and B is the hydrogen atom or a group with the formula
- --SiR.sub.2 R.sup.1
- in which R is a monovalent hydrocarbon group and R.sup.1 is the hydrogen atom, vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, 3-methacryloxypropyl, 3-acryloxypropyl, 3-chloropropyl, 3-glycidoxypropyl, 3-aminopropyl, or 3-hydroxypropyl, by first subjecting
- (A) a cyclic trisiloxane with the formula
- (R.sub.2 SiO).sub.3
- in which R is a monovalent hydrocarbon group to nonequilibration polymerization, optionally in the presence of
- (B) a silane or siloxane with the formula
- R(R.sub.2 SiO).sub.m H
- in which R is a monovalent hydrocarbon group and m is an integer with a value of at least 1, under the effect of a
- (C) a lithium polymerization catalyst with the formula
- R(R.sub.2 SiO).sub.n Li
- in which R is a monovalent hydrocarbon group and n is an integer with a value of at least zero to twenty, and subsequently terminating said nonequilibration polymerization with
- (D) a compound selected from the group consisting of an acid and a halosilane with the formula
- R.sup.1 R.sub.2 SiX
- in which R and R.sup.1 are defined above, and X is a halogen atom, characterized in that the silanol-containing impurity present in the cyclic trisiloxane (A) is preliminarily silylated with
- (E) a silylating agent.
A method for the preparation of a diorganopolysiloxane with the formula
- R(R.sub.2 SiO).sub.p B
- in which R is a monovalent hydrocarbon group, p is an integer with a value of at least 1, and B is the hydrogen atom or a group with the formula
- --SiR.sub.2 R.sup.1
- in which R is a monovalent hydrocarbon group and R.sup.1 is the hydrogen atom, vinyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, 3-methacryloxypropyl, 3-acryloxypropyl, 3-chloropropyl, 3-glycidoxypropyl, 3-aminopropyl, or 3-hydroxypropyl, by first subjecting
- (A) a cyclic trisiloxane with the formula
- (R.sub.2 SiO).sub.3
- in which R is a monovalent hydrocarbon group, to nonequilibration polymerization, in the presence of
- (B) a silane or siloxane with the formula
- R(R.sub.2 SiO).sub.m H
- in which R is a monovalent hydrocarbon group and m is an integer with a value of at least 1, under the effect of
- (C) a lithium polymerization catalyst with the formula
- R(R.sub.2 SiO).sub.n Li
- in which R is a monovalent hydrocarbon group and n is an integer with a value of at least zero to twenty, and subsequently terminating said nonequilibration polymerization with
- (D) a compound selected from the group consisting of an acid and a halosilane with the formula
- R.sup.1 R.sub.2 SiX
- in which R and R.sup.1 are defined above, and X is a halogen atom, characterized in that the silanol-containing impurity present in the cyclic trisiloxane (A) is preliminarily converted into a lithiated material by lithiation with
- (F) an organolithium compound and said lithiated material is then silylated with
- (G) a silylating agent that contains silicon-bonded halogen.
Dependencies are inferred from the claim text.