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 polya mide degradation was carried out by using N,N'-dihexylterephthalamide (DHT) and N,N'-dihexylisophthalamide (DHI) as models of the amide func tionality. DHT was reacted in an inert argon atmosphere at 350 degrees 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 w ith the addition of 0.5% CuI. Increases to 5 wt % did not change the d isappearance kinetics further. Comparison of the behavior of DHT and D HI revealed that changes in rate of disappearance and product yields w ere dependent on the relative positions of the amide substituents. Rea ction of DHI was enhanced more significantly at a given CuI loading. T he rate of disappearance of DHI and DHT and the selectivity to N-hexyl benzamide increased with the addition of water in loadings ranging fro m 0.148M to 0.193M. The reactivity of DHI was more greatly enhanced at a given water loading. These differences were attributed to electroni c effects, as evaluated by differences in atomic partial charges, and physical effects. (C) 1995 John Wiley and Sons, Inc.