| abstract |
The preparation of thermoplastic copolycarbonates, containing no unwanted branching, comprises the melt phase reaction of 0.1-35 mol.% 4,4-dihydroxydiphenylene of formula (I) and 65-99.9 mol.% other diphenol of formula (II) in the presence of 10<-4> to 10<-8> moles phosphonium compound catalyst of formula (R13)(R14)(R15) P<+>R15 Y<-> (III) per mole (II). In the formula, R1-R8 = H or 1-3C alkyl; R9-R12 = H, CH3, Cl or Br; X = 1-5C alkylene, 2-5C alkylidene, 5-6C cycloalkylene, 5-10C cycloalkylidene, -C(O)-, S or O; R13-R16 = 1-10C alkyl, 6-10C aryl, 5-10C cycloalkyl, 7-10C methyl-substituted aryl or 6-10C methyl-substituted cycloalkyl; and Y = anion belong to an acid-base pair (HY) with a pKb less than 11. |