Shock-initiation chemistry of nitroarenes

The authors present evidence that the shock-initiation chemistry of nitroarenes is dominated by the intermolecular hydrogen transfer mechanism discussed previously. The acceleration by pressure, kinetic isotope effect, and product distribution are consistent with the bimolecular transition state kinetic isotope effect, and product distribution are consistent with the bimolecular transition state rather than rate-determining C-N homolysis.GC-MS analysis of samples which were subjected to a shock wave generated by detonation of nitromethane shows that nitrobenzene produces aniline and biphenyl, and o-nitrotoluene forms aniline, toluene, o-toluidine and o-cresol, but not anthranil, benzoxazinone, or cyanocyclopentandiene. In isotopic labeling experiments o-nitrotoluene and TNT show extensive H-D exchange on their methyl groups, and C-N bond rupture is not consistent with the formation of aniline from nitrobenzene or nitrotoluene, nor the formation of o-toluidine from o-nitrotoluene. Recent work incorporating fast TOF mass spectroscopy of samples shocked and quenched by adiabatic expansion shows that the initial chemical reactions in shocked solid nitroaromatic explosives proceed along this path.