| 摘要 |
Polycarbonates having aliphatically bound chlorine are made by (a) forming an intermediate polycarbonate having recurring units of formula <FORM:1084601/C3/1> wherein each R unit is of the formula <FORM:1084601/C3/2> in which R1 and R11 are chlorine or hydrogen atoms, (b) dissolving the intermediate polycarbonate in a solvent, e.g. a chlorinated hydrocarbon, and (c) passing chlorine or a chlorinating agent into the solution in the presence of a chlorination promoting agent. The intermediate polycarbonate is made by reacting the corresponding bisphenol with phosgene either (i) in the presence of a tertiary amine and, possibly, an inert solvent or (ii) by the usual interfacial method. Chlorination may be effected by means of chlorine, sulphuryl chloride or phosphorus pentachloride in the presence of visible light and/or ultra-violet radiation and/or a free-radical catalyst and, possibly, a hydrogen halide acceptor (e.g. water and/or calcium carbonate). |
