EVIDENCE OF CARBENES IN THE EXPLOSION CHEMISTRY OF NITROAROMATIC ANION-RADICALS

The solid potassium salts of the nitrobenzene anion radical [K+C6H5NO2 (solid.-)] and all three nitrotoluene anion radicals were generated vi a the potassium reduction of the nitroaromatic in liquid ammonia follo wed by removal of the ammonia. These solid salts were found to be very shock- and impact-sensitive explosives, which emit a number of gasses , including CO, CO2, CH4, and Hz, upon detonation. No other low molecu lar weight products are formed, and mass spectral analysis of the soli d ''ash'' shows that all organic components of it are polymeric in nat ure. The initiation step in the detonations appears to be the cleavage of the C-NO2 bond (e.g., K+C6H5NO2(solid.-) --> C6H5. + KNO2(solid)). The polymerization results in the release of the hydrogen gas, and tr apping experiments indicate that the methane is formed from an interme diate carbene that reacts with the molecular hydrogen. Indeed, carryin g out the explosions under an atmosphere of CH4 results in the formati on of ethane, presumably via carbene insertion into the H3C-H bond. On the basis of this and deuterium labeling experiments, a mechanism is proposed that accounts for the formation of NO2- (detected via IR in t he ash) H-2, CH4, and polymeric material.