Studies on thermal degradation of riot control agent dibenz[b,f]-1,4-oxazepine (CR)

摘要

The riot control agent dibenz[b,f]-1,4-oxazepine (CR) is widely used by the law enforcement agencies. Since it is mostly dispersed using explosive device to cause the desired effect, studies have been carried out by exploding CR shells and adsorbing the emanated gases on Tenax TA (R) sorbent tubes. The adsorbed gases are then subjected to automatic thermal desorption - gas chromatography mass spectrometry (ATD-GC-MS) for identification of the components. Flash (analytical) pyrolysis and thermo gravimetric analysis (TGA) have also been conducted in inert atmosphere to simulate the thermal conditions that CR experiences during the process of explosive dispersion. The study has helped to understand thermal stability, identification and quantification of gaseous pyrolysis products of CR. The data has revealed that CR undergoes sublimation with trace decomposition below 500 degrees C. Apart from the products found in real time studies, a large number of mono aromatics and polycyclic aromatic hydrocarbons are observed to be formed at about 800 degrees C. The mechanism of pyrolysis is proposed on the basis of the determined pyrolysates and their relative abundance. The investigation results provide significant information for understanding thermal behaviour of CR.