| Popis: |
The review is concerned with the analysis of the published data on the synthesis of polybenzazoles (polybenzoxazoles, polybenzimidazoles, polybenzthiazoles) in presence of acid catalysts. It is shown that all the main methods of synthesizing polybenzazoles — “Marvel reaction”, “Iwakura reaction” two-stage polycyclocondensation, high temperature polycyclocondensation in organic solvents, reductive polyheterocyclization—contain in themselves elements of catalytic polycyclocondensation. From a number of examples it is shown that the use of acid catalysts allows one not only to lower the temperature and shorten the duration of synthesis of the polybenzazoles but also to obtain polymers with an essentially new complex of properties. |
