Thermochemical Decomposition of TNT: Radical Identification and Theoretical Studies

摘要

The thermochemical decomposition of 2,4,6-trinitrotoluene (TNT) has been studied experimentally with EPR and theoretically with the MNDO and MINDO/3 methods. Analysis of the EPR spectra of pure TNT and hexamethylbenzene (HMB)-doped TNT at elevated temperatures has afforded an identification of one of the initial radicals formed in these systems. In both cases the radical is the one formed by removal of the nitro group from TNT. MNDO and MINDO/3 results indicate that removal of a nitro group from 1-nitropropene, used as a model system for TNT, is likely. Comparisons of the theoretical activation energy and the deuterium kinetic isotope effect for this step are in excellent agreement with measured values for these quantities early in the TNT decomposition. The nitro group removal is apparently facilitated by interaction with a second molecule in the system (HMB in the binary system or another TNT in the pure TNT system), which weakens the C-NO2 bond either by transferring a hydrogen atom or forming a charge-transfer complex. Other potential first steps in the mechanism have been investigated theoretically. (Author)