Tetranitroacetimidic acid (TNAA) is an exotic new compound that shows promise as an oxidizer in propellants for rockets and missiles (J. Am. Chem. Soc. 2014, DOI: 10.1021/ja5074036). Although ammonium perchlorate has long been used for that purpose, it comes with a number of environmental concerns, including groundwater contamination, acid rain, and ozone layer depletion. Thao T. Vo and Jean’ne M. Shreeve of the University of Idaho and Damon A. Parrish of the Naval Research Laboratory came up with TNAA as a possible green substitute. The researchers treated the well-known insensitive energetic material 1,1-diamino-2,2-dinitroethene (FOX-7) with fuming nitric acid at room temperature to make TNAA in better than 93% yield. The new compound has high enough oxygen content for promoting complete oxidations, they note. Compared with ammonium perchlorate, TNAA is more impact stable, and calculations suggest that it would be a more efficient propellant, although the compound is less stable to heat and friction. The researchers also found that combining TNAA with triflic acid yields a cocrystal salt, which they suggest could be used as a precursor for other energetic materials.