GB1518591A - Epoxy-functional organopolysiloxanes - Google Patents

Abstract

1518591 Epoxy-functional organopolysiloxanes SWS SILICONES CORP 7 April 1976 [7 April 1975] 14094/76 Heading C3T An epoxy-functional organopolysiloxane is prepared by a process which comprises reacting an epoxy-functional organosilicon compound containing a hydrocarbonoxy group with an organocyclopolysiloxane in the presence of a lithium compound. Little, if any, equilibration occurs in the process. The epoxy-functional organosilicon compound may be a silane of the formula or a siloxane of the formula where R<1> denotes a hydrogen atom or a monovalent hydrocarbon radical having up to 18 carbon atoms, or the two R<1> radicals together with the carbon atoms to which they are attached denote a carbocyclic group; R<2> denotes a monovalent hydrocarbon radical of up to 18 carbon atoms; R<3> denotes a divalent hydrocarbon or oxahydrocarbon radical of from 2-18 carbon atoms; R<4> denotes a radical of the formula R<1>O0À5 or R<2>3SiO0À5; X denotes a hydrogen atom or a monovalent organic radical; Z denotes a radical of the formula R<1>O, R<1> or R<2>3SiO; a denotes a positive-integer up to 20,000; b denotes 1, 2 or 3, c denotes 0, 1, 2 or 3 with the proviso that if c denotes o or if no symbol R<4> denotes a radical of the formula R<2>O0À5 then at least one symbol Z must denote the radical R<2>O; d denotes 0, 1, 2 or 3, with the proviso that the average value of d exceeds 0; and e denotes 0, 1 or 2 with the proviso that b + e and d + e do not exceed 3. Preferably R<1> and R<2> denote alkyl groups. The organocyclopolysiloxane preferably has the formula [R<2>2SiO]z where Z is 3 or 4. The lithium compound may be a lithium alkoxide, a lithium alkyl, a lithium alkenyl, a lithium aryl, lithium hydroxide, a lithium hydride or a lithium silanoate. The reaction may be carried out at a temperature of 25-150‹ C. under an inert atmosphere and optionally in the presence of an aprotic solvent, at least part of which has Lewis base characteristics, e.g. tertiary amines, ethers and dimethyl sulphoxide, the rest of the solvent being a hydrocarbon aprotic solvent. After completion of the reaction the lithium compound is preferably removed, e.g. by washing with water or by neutralization with an acid. In the Examples epoxy-functional organopolysiloxanes are prepared either (1) by reacting hexamethylcyclotrisiloxane or octamethyl cyclotetrasiloxane and gamma-glycidoxypropyltrimethoxysilane in the presence of n-butyllithium using benzene and diethylene glycol dimethyl ether as solvent, or (2) by first heating a mixture of gamma-glycidoxypropyltrimethoxy silane, lithium hydroxide, water and methanol, then removing the volatiles and then reacting the product with hexamethylcyclotrisiloxane using benzene and tetrahydrofuran as solvent. The catalyst is neutralized with acetic acid.