Synthesis of polyamides by direct polycondensation with (1,2-benzisoxazol-3-yl) diphenyl phosphate as a new activating agent

A new activating agent for amide condensations, (1,2-benzisoxazol-3-yl) diphenyl phosphate ( 1 ), was readily prepared in high yield by the reaction of 1,2-benzisoxazol-3-ol ( 2 ) with diphenyl phosphorochloridate ( 3 ) in the presence of triethylamine in benzene. The new activating agent 1 was found to be very useful for the preparation of amides from carboxylic acids and amines. The direct polycondensation of several dicarboxylic acids with aromatic diamines using the activating agent 1 in the presence of triethylamine proceeded slowly at room temperature to produce polyamides with inherent viscosities up to 1.2 dL g^?1.