Explosion and Decomposition Characteristics of Hydrazoic Acid in the Gas Phase

The formation of hydrazoic acid HN3 is inherent to many azide processes due to the presence of small amounts of protic components in the reaction mixtures. Hydrazoic acid is an unstable component which may decompose violently. To ensure safe working conditions during the development or the production of azides, the lower decomposition limit (LDL) of this substance in a nitrogen atmosphere was determined using a 5-L explosion sphere. No decomposition could be observed for HN3 concentrations below 10%. Moreover, the influence of solvent vapors was investigated to demonstrate that they can be used to inhibit the decomposition reaction of hydrazoic acid.