Reactions in the presence of organic phosphites, I: High temperature amidation in the absence of solvents

Abstract

Abstract When reacted for periods of 5–10 min at temperatures of about 280–300°C in the presence of certain organic phosphites polymers that contain available carboxy and aliphatic amine groups undergo amidation. This reaction can increase the molecular weight of many aliphatic polyamides by their self‐reaction in an extruder. Block or graft copolymers can be formed by reacting polymers that contain aliphatic amines with others that contain carboxyl. Studies of model compounds in the companion article (II) indicate that polymerization proceeds through an diaryloxy or dialkoxy amino phosphine intermediate to produce amide bonds and disubstituted phosphite reaction by‐products. In the absence of primary amines in the reaction mixture an ester is slowly formed from the carboxyl end group of the polymer and the oxysubstituent of the phosphite. In no case was a phosphorus‐containing mixed anhydride detected. The mechanistic identity of the low temperature reactions in article II and the high temperature reactions in this article has not been proved conclusively, however.