| 摘要 |
1,267,568. Polymerization of cyclic siloxanes in the presence of metal complexes. GENERAL ELECTRIC CO. 10 June, 1969 [24 June, 1968], No. 29430/69. Heading C3T. Essentially linear polydiorganosiloxanes are prepared by heating a cyclic organosiloxane [R<SP>1</SP>R<SP>11</SP>SiO]x, wherein R<SP>1</SP> and R<SP>11</SP> are each H or a monovalent hydrocarbon, halohydrocarbon or cyanoalkyl radical and x is 3-7 with a complex of a compound M<SP>++</SP> R- - or M<SP>++</SP> (R<SP>-</SP>) 2 , wherein M is Be, Mg, Ca, Sr or Ba and R is a polynuclear hydrocarbon or conjugated hydrocarbon, with an aprotic dipolar solvent. The complex is prepared by reaction of the metal with the hydrocarbon in the presence of the solvent; it may be used after isolation with the molten cyclic siloxane or dispersed in the complexing solvent or a different aprotic solvent. In Examples complexes are prepared of hexamethyl-phosphoramide with Ba diphenylethylene, Ba and Ca cyclooctatetraenes, Ba trans-stilbene, Sr tetraphenylethylene and Mg m-terphenyl and of tetrahydrofuran with Ba diphenylethylene. A few drops of the product solutions are added to melts of: trans- or cistrimethyl triphenyl cyclotrisiloxane, alone or mixed with tetramethyl tetrakis-cyanoethyl cyclotetrasiloxane or hexaphenyl cyclotrisiloxane; hexamethyl cyclotrisiloxane, alone or mixed with tetramethyl tetrakis-cyanoethyl cyclotetrasiloxane; or tricyclopentamethylene cyclotrisiloxane. |
