| Abstract: | Mechanistic features of the reaction promoted by thionyl chloride and amides such as N-methylpyrrolidone (NMP) were studied. The reaction was effective in the amidation of carboxylic acids, but not effective in the esterification. The amidation was affected by the kind and the amount of amides used, most favorably by two equivalents of NMP with respect to the acid. These amides were assumed to be involved in the intermediate formation, and the reaction was proposed to proceed via Vilsmeier adducts derived from thionyl chloride and the amides, and through activation of a carboxylic acid different from an acyl chloride. The reaction was successfully applied to the direct polycondensation of aromatic dicarboxylic acids and diamines in NMP at 70°C to produce polyamides with high molecular weights. Initial reaction of dicarboxylic acids with the adducts, additive effect of tertiary amines, and polycondensation temperatures were studied in terms of the inherent viscosity of the polymers produced. |
