The decomposition of spent PETN nitration acids

The decomposition of PETN in pure nitric acid and of spent acids from nitrating pentaerythritol (PE) was followed by a continuous differential temperature measurement against a blank. Decomposition was more rapid as the temperature was raised and attained a maximum rate between 65–75% HNO 3 . Spent nitrating acids decomposed more rapidly than pure acids with PETN, due to the presence of about 0.5% dipentaerythrital hexanitrate (DiPEHN) formed from dipentaerythritol in the original PE. The decomposition of PETN in nitric acids was strongly catalysed by NO 2 , especially at high acid strength. The course of the decomposition as deduced from this evidence appeared to embrace (1) hydrolysis, (2) oxidation of hydrolysis products liberating NO 2 , (3) destruction of PETN by a mechanism catalysed by NO 2 in which hydrolysis plays no part.