Verbeterde werkwijze voor het bereiden van hoogmoleculaire lineaire thermoplastische polycarbonaten

In the manufacture of linear polycarbonates by reacting an aqueous alkaline solution or suspension of a dihydric phenol with phosgene or a dichlorocarbonic acid ester of a dihydric phenol in the presence of a water-immiscible organic solvent for the polycarbonate formed, there is added as a catalyst a quarternary phosphonium compound, a quaternary arsonium compound or a tertiary sulphonium compound, either as a free base or as a salt thereof. The reaction mixture may also include an acid chloride of an aliphatic, cycloaliphatic or aromatic dicarboxylic acid or a dichlorocarbonic acid ester of an aliphatic or cycloaliphatic glycol. The dihydric phenol may be a dihydroxy benzene or naphthalene or it may be a bis-phenol in which the hydrogen benzene radicals are connected together by one or more groups selected from alkylene, alkylidene, cycloaliphatic, tertiary amino, carbonyl, sulphide, sulphoxide, sulphone or ether radicals. The alkylene is alkylidene, groups may be substituted by hydrocarbon or halogenated hydrocarbon groups and the hydroxyaromatic groups may be substituted by hydrocarbon, hydrocarbonoxy, halogenated hydrocarbon, halogenated hydrocarbonoxy, nitro or halo groups. In examples, in which the dihydric phenol is dissolved in aqueous sodium hydroxide solution and the organic solvent used is methylene chloride, polycarbonates are made by reacting (1)-(7), (10)-(15), (22)-(25), (27) and (28), bisphenol-A and the dichlorocarbonic acid ester of bisphenol-A; (8), (9) and (26) bisphenol-A and and phosgene; (16) and (17) 2,2-bis-(4-hydroxy-3,5-dichlorophenyl) propane and the dichlorocarbonic acid ester of bisphenol-A; (18) and (19) bis-(4-hydroxy-3-methylphenyl) methane and the dichlorocarbonic acid ester of bisphenol-A; (20)-(21) 1,1-bis-(4-hydroxyphenol)-2,2,2-trichloroethane and the dichlorocarbonic ester of bisphenol-A. The polycarbonates are suitable for the manufacture of fibres and films.