Synthesis of aromatic polyamides by 1‐hydroxybenzotriazole‐catalyzed polycondensation of active aromatic diesters with aromatic diamines

Catalytic actions of various additives were studied in the polycondensation of di(4‐nitrophenyl) isophthalate with bis(4‐aminophenyl) ether in N‐methyl‐2‐pyrrolidone, and 1‐hydroxybenzotriazole (HOBt) was found to be a highly effective catalyst that yielded high‐molecular‐weight polyamide. In addition to the polycondensation of the 4‐nitrophenyl ester, the polymerization of negatively substituted phenyl esters like di(2,4,5‐trichlorophenyl) isophthalate was also accelerated by HOBt. For the HOBt‐catalyzed aminolysis of esters a bifunctional concerted mechanism that involves an eight‐membered transition state was proposed.