| 摘要 |
Polycarbonates are made by reacting phosgene with a dihydric phenol of formula <FORM:1028151/C3/1> where the sum of x and y is 6 or 8. Reaction may be effected in the presence of (a) a solvent selected from toluene, methylene chloride and an aqueous solution of an alkali metal hydroxide, (b) an agent combining with the liberated hydrogen chloride (e.g. an amine or an alkali metal hydroxide), (c) a catalyst (e.g. a quarternary ammonium salt or a tertiary amine and (d) an antioxidant (e.g. sodium dithionite). A one-stage reaction may be used or the dihydric phenol may first be converted into its bischloroformate which is then reacted with additional dihydric phenol. The chlorinated dihydroxybiphenyl may be partly replaced by other dihydric phenols, e.g. dihydroxy diphenyl alkanes, -sulphones, -sulphoxides, -sulphides or -ethers or by dihydroxy diphenyls or the same nuclear substituted by alkyl, acyl, alkoxy or halogen groups. The products are soluble in methylene chloride, chloroform and dimethyl formamide. |
