Conversion of acetamido- and nitro-substituted ortho-azidonitro derivatives of 2,3,4,5-tetrahydrobenzo [b][1,4]dioxocin to the corresponding furoxans and furazans in the gas phase

Electron impact ionization of the five isomeric 2,3,4,5‐tetrahydro‐9‐azido‐7,8‐dinitro‐, 2,3,4,5‐tetrahydro‐8‐azido‐7,9‐dinitro‐, 2,3,4,5‐tetrahydro‐8‐azido‐7,10‐dinitro‐, 2,3,4,5‐tetrahydro‐7‐azido‐8,9‐dinitro‐, 2,3,4,5‐tetrahydro‐7‐azido‐8,10‐dinitro‐ and the related 2,3,4,5‐tetrahydro‐7‐acetamido‐8‐azido‐9‐nitro‐, 2,3,4,5‐tetrahydro‐7‐acetamido‐9‐azido‐8‐nitro‐, 2,3,4,5‐tetrahydro‐9‐acetamido‐7‐azido‐8‐nitro‐, 2,3,4,5‐tetrahydro‐10‐acetamido‐7‐azido‐8‐nitrobenzo[b] [1,4]dioxocin derivatives furnished, after elimination of nitrogen, the corresponding nitro and acetamido dioxocino‐annelated benzofuroxans. Further loss of oxygen from the latter afforded the corresponding benzofurazans. It was shown in two cases that these processes occur primarily upon electron impact ionization, without excluding some small fraction undergoing a thermal degradation process. The proposed fragmentation patterns are supported by high‐resolution and mass‐analyzed ion kinetic energy spectroscopic data. Similar work on the unsubstituted 6,7‐dihydro[1,4]dioxino[2,3‐f]‐ and 7,8‐dihydro‐6H‐[1,4]dioxepino[2,3‐f]‐2,1,3‐benzoxa‐diazole 1‐oxide reveal that loss of oxygen from the molecular ion to furnish the corresponding benzofurazans is the result of electron impact ionization (at least in part).