| Abstract: | Tristrimethylsilyl-3-amino-4-hydroxybenzoic acid was condensed with various aromatic acetoxy carboxylic acid chlorides in Marlotherms-S® at 20–350°C. Under these conditions formation of an amide group, ring closure to benzoxazole groups and polycondensation occur step by step in a “one-pot procedure”. The crude polyesters were hydrolyzed to yield pure 2-(hydroxyaryl) benzoxazole-5-carboxylic acids which were acetylated and polycondensed. The pure polyesters obtained in this way were characterized by viscosity and DSC measurements, WAXS-powder patterns, and thermogravimetric analyses. The polyester of 2-(4-hydrophenyl) benzoxazole-5-carboxylic acid has a degree of crystallinity > 90% and a short term in thermostability in air up to 500°C. |
