A methodological approach to N,N-dialkylamide thermal degradation at low temperatures

N,N-dialkylamides such as N,N-di-(2-ethylhexyl)-3,3-dimethylbutyramide (DEHDMBA) are of interest as extractants for the reprocessing of nuclear fuel. The aim of this study was to investigate the thermal behaviour of these extractants at low temperatures by a Doehlert experimental design. According to the three second-order models proposed, DEHDMBA degradation appeared to be complex. The oxygen level was the most influential parameter, almost four times as significant as the temperature and time. Moreover, the residual amount of DEHDMBA between 174 and 215C in ambient air could be predicted very accurately within 6%, which was close to the experimental error. The formation of the major degradation products was also very dependent on the oxygen level. However, yields of low molecular weight carboxylic acids and primary amides were increased by operating at high temperature and with long reaction times