Pyrolysis Studies Of The Burning Mechanisms Of High-Nitrogen Compounds

The chemical origin of the burning rate differences of 5-amino-1H-tetrazole (5-ATZ) and its hydrohalide (HCl, HBr, HI) salts were revealed by flash pyrolysis at 350degreesC, 400degreesC and 450degreesC by T-jump/FTIR spectroscopy. Comparison of the products indicated that two global decomposition channels exist. The first channel is dissociation of the salt to form HX and 5-ATZ followed by decomposition of neutral 5-ATZ. The second channel involves decomposition of the [5-ATZH](+) ion directly. The ratio of these two channels depends on the compound. The 5-ATZ channel is favored over the [5-ATZH](+) channel in the order HCl > HBr > HI, which is the trend of the pK(a) values of these acids. This information enables both the ordering of the burning rates as a function of pressure as well as the trend in the pressure dependence to be rationalized. Similar studies on the azo and hydraza-bridged amino- and nitrofurazans reveal that the hydraza linkage converts to the azo linkage early in the decomposition sequence and before the remainder of the compound decomposes. This leads to the prediction that the azo and hydraza-bridged compounds may have similar burning rates.