Thermal decomposition of energetic materials 76: chemical pathways that control the burning rates of 5-aminotetrazole and its hydrohalide salts

The hydrohalide (HCl, HBr, HI) salts of 5-amino-1H-tetrazole (5-ATZ) were flash pyrolyzed under 0.5 MPa of Ar by T-jump/FTIR spectroscopy, and the gaseous products were determined at 350°C, 400°C, and 450°C. Comparison of the products indicated that two global decomposition pathways exist, which give somewhat different products. 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-ATZ]+ ion directly. The ratio of these two channels depends on the compound. The first channel is favored over the second channel in the order HCl > HBr > HI, which is the trend of the pKa 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 of the individual burning rates of these compounds to be rationalized.