Structure/Reactivity relationships for high‐performance polyamides: Kinetics of the reactions of N,N′‐dihexylphthalamides in the presence of added copper iodide and water

An experimental study to determine the effect of copper(I) iodide and water on the rate and product distribution of aliphatic‐aromatic polyamide degradation was carried out by using N,N′‐dihexylterephthalamide (DHT) and N,N′‐dihexylisophthalamide (DHI) as models of the amide functionality. DHT was reacted in an inert argon atmosphere at 350°C in the presence of CuI added in amounts ranging from 0–5% by weight. The rate of disappearance of DHT was enhanced by a factor of three with the addition of 0.5% CuI. Increases to 5 wt % did not change the disappearance kinetics further. Comparison of the behavior of DHT and DHI revealed that changes in rate of disappearance and product yields were dependent on the relative positions of the amide substituents. Reaction of DHI was enhanced more significantly at a given CuI loading. The rate of disappearance of DHI and DHT and the selectivity to N‐hexylbenzamide increased with the addition of water in loadings ranging from 0.148M to 0.193M. The reactivity of DHI was more greatly enhanced at a given water loading. These differences were attributed to electronic effects, as evaluated by differences in atomic partial charges, and physical effects. © 1995 John Wiley & Sons, Inc.