| 摘要 |
High molecular weight polycarbonates are prepared from hindered bisphenols in a reaction sequence involving conversion of the hindered bisphenol to the corresponding bischloroformate and subsequent treatment with an amine catalyst and aqueous base to effect polymerization by hydrolysis and condensation of the bischloroformate groups. Tertiary aliphatic and cycloaliphatic amine catalysts bearing at least one methyl group are found to be especially effective in promoting this polymerization reaction. Reaction rates and selectivities are shown to be superior to known methods employing tertiary amines lacking methyl groups attached to nitrogen, such as triethylamine. The inclusion of chain stoppers allows the preparation of well defined mixtures of polycarbonate oligomers from hindered bisphenols. Additionally, the methodology may be used to prepare symmetrical diaryl carbonates from hindered phenols. |
