The present invention relates generally to explosive compositions, and more particularly to the ethylenediamine salt of 5-nitrotetrazole and mixtures thereof.
Ammonium nitrate is an inexpensive and readily available oxidizer used extensively in commercial explosives. Unfortunately, one of the disadvantages of this material which limits its utility for military explosives is its nonideal behavior. Generally, detonation pressures and velocities are lower which results in lower power output for nonideal explosives when compared to ideal explosives. Over the past ten years, attempts have been made to obtain ideal explosive behaviour from composites of ammonium nitrate with various fuels. The most promising of these investigations has involved the formation of low-melting eutectic mixtures of the fuel under investigation and ammonium nitrate. The eutectics offer the advantage of being readily castable for military applications. Moreover, the intimate mixing of the component substances which results when eutectic mixtures are cooled below their melting temperatures offers the best opportunity for obtaining close to ideal performance. That is, the fuel and the ammonium nitrate oxidizer interact and detonate as a single component rather than as individual components.
The ammonium salt of 3,5-dinitro-1,2,4-triazole was found to form a low-melting eutectic with ammonium nitrate that was subsequently shown to perform as a near ideal explosive. Indeed, eutectic compositions involving ammonium nitrate and ammonium salts of several nitroheterocycles have been described in U.S. Pat. No. 4,300,962 "Ammonium Nitrate Explosive Systems," issued to Mary M. Stinecipher and Michael D. Coburn. However, the ammonium salt of 3,5-dinitro-1,2,4-triazole performed best as an explosive. This discovery was the basis for searching for a more efficient and less hazardous procedure for producing this compound which is the subject of U.S. Pat. No. 4,236,014. "Production of the Ammonium Salt of 3,5-dinitro-1,2,4-triazole by Solvent Extraction," issued to Kien-yin Lee and Donald G. Ott on Nov. 25, 1980. Neither of the above-described patents teaches the use of the ethylenediamine salt of 5-nitrotetrazole as the fuel in an ammonium nitrate eutectic or the preparation of this material. The former patent does mention the ammonium salt of 5-nitrotetrazole and its preparation, however. The finding that ammonium based mixtures could be made which exhibited near-ideal explosive performance further encouraged the search for other, less expensive materials that would form similar eutectics or solid solutions with ammonium nitrate, which search led to the subject invention.
W. H. Gilligan and M. J. Kamlet describe the preparation of metallic salts of 5-nitrotetrazole in "Synthesis of Mercuric-5-nitrotetrazole," Naval Surface Weapons Center Report NSWC/WOL/TR 76-146, Dec. 1976. However, their procedure involves the step of isolating the extremely sensitive copper salt of 5-nitrotetrazole. The subject process eliminates this hazardous step and demonstrates a one-pot process for obtaining a solution of the insensitive sodium salt as precursor to the organic salts of interest.