Synthesis of polycarbonates by a silicon-assisted alkoxy/carbonylimidazolide coupling reaction

The investigation of a silicon-mediated coupling reaction between hydroxyl and carbonylimidazolide functional groups in the preparation of carbonate linkages is described. Application of this reaction to the formation of aliphatic polycarbonates was accomplished by the polymerization of an AB monomer unit, which was composed of 1,4-cyclohexanediol, where one of the hydroxyl groups was protected as a dimethylphenylsilyl ether and the other carried the carbonylimidazolide functionality. Reaction of this monomer with cesium fluoride removed the silicon protecting group and the resulting alkoxy anion promoted polymerization. Poly(1,4-cyclohexanecarbonate)s with typical molecular weights of M_w = 20,000 and M_n = 7300 a.m.u. (from GPC based upon polystyrene standards) were prepared in ca. 65% yield. The polymer showed a glass transition temperature at 138°C by DSC. TGA gave 85% mass loss between 275 and 350°C. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1133–1137, 1997.