Compelling evidence has been found for the formation and direct detection of the cyclopentazole anion (cyclo-N ) in solution. The anion was prepared from phenylpentazole in two steps: reduction by an alkali metal to form the phenylpentazole radical anion, followed by thermal dissociation to yield cyclo-N . The reaction solution was analyzed by HPLC coupled with negative mode mass spectrometry. A signal with m/z 70 was eluted about 2.1 min after injection of the sample. Its identification as N was supported by single and double labeling with N, which yielded signals at m/z=71 and 72, respectively, with identical retention times in the HPLC column. MS/MS analysis of the m/z=70 signal revealed a dissociation product with m/z=42, which can be assigned to N . To our knowledge this is the first preparation of cyclo-N in the bulk. The compound is indefinitely stable at temperatures below -40 °C, and has a half-life of a few minutes at room temperature.

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Irradiation of the energetic polymer GAP (glycidyl azido polymer) by a high power pulsed UV laser leads to its rapid decomposition. A large amount of solid and gaseous material is released, and in the presence of an inert gas, a shock wave develops. Comparison with an inert polymer indicates that the energy released by the exothermicity of the decomposition reaction contributes significantly to the shock formative energy. The energy released in the micro‐explosion can be estimated from the analysis of the shock front propagation velocity. It is found that irradiation of polymers in which GAP is diluted by an inert polymer, may lead to a higher shock intensity than irradiation of neat GAP. Possible causes for this apparent inconsistency (which is not observed upon initiation by a pulsed infrared laser) are discussed.

The cyclopentazolate anion, N, has been researched extensively over the years and detected in the gas phase more than a decade ago, but was only recently measured in solution. The process whereby aryl pentazole reduction leads to the production of N is still not fully understood. Here, the production of N in solution was investigated using isotopic labeling techniques while implementing changes to the synthesis methodologies. N labeled phenyl pentazole produced appropriately labeled phenyl pentazole radical anions and N which, upon collision induced dissociation, produced the expected N signals. Changing to higher purity solvent and less coated Na metal allowed for a much more rapid pace, with experiments taking less time. However, the best yields were obtained with heavily coated metal and much longer reaction times. Utilization of a vacuum line and ultrapure solvents led to no products being detected, indicating the importance of a sodium passivation layer in this reaction and the possibility that sodium is too strong a reducer. These findings can lead to better production methods of N and also explain past failures in implementing aryl pentazole reduction techniques.