Cupric salt of 5-nitrotetrazole

Fig. 8.2 Crystals of the cupric salt of 5-nitrotetrazole [47]. Reprinted by permission of the Department of the Navy employees, M. Bichay, K. Armstrong, R. J. Cramer and the Pacific Scientific employess, J. Fronabarger and M. D. Williams...

Metallic salts are mostly soluble in water (e.g., alkaline, salts of alkaline earths, cadmium, and thallium). The silver, mercury, cobalt, and nickel salts are insoluble in cold water cobalt and cupric salts give a dihydrate [4]. Nitrotetrazole salts have good chemical stability and are not sensitive to carbon dioxide nor influenced by moisture. They may be stored without deterioration in hot and humid climates [1]. The cupric salt of 5-nitrotetrazole is not hygroscopic [48]. The crystals of this salt are shown in Fig. 8.2. 

The cupric salt of 5-nitrotetrazole has been studied as a potential green primary explosive by Fronabarger, Sanborn and Bichay et al. [48]. The values of sensitivity and performance reported by these authors are sununarized in Tables 8.8 and 8.9. Bagal reported an ignition temperamre of 224 °C (heating rate 5 °C min ) [2]. 

Table 8.8 Sensitivity and DSC data of the cupric salt of 5-nitrotetrazole [48]...

Brisance of the cupric salt of 5-nitrotetrazole at various densities has been measured by the plate dent test (see results in Table 8.9). Cu(NT)2 detonates even at low density but it did not match the performance achieved by LA [47, 48]. This may be because of its longer DDT compared to LA. It is interesting that the method used for synthesizing has a significant impact on the detonation parameters of Cu(NT)2. The cupric salt of 5-nitrotetrazole prepared from NaNT and a cupric salt detonates in witness plate test while the same compound prepared directly by hydrolysis of an acidic cupric salt of 5-nitrotetrazole does not detonate [48]. 

The cupric salt of 5-nitrotetrazole has also been recendy studied as a promising alternative green LA replacement [47, 48, 60, 62]. 

The cuprous salt of 5-nitrotetrazole is prepared by the reaction of the sodium salt of 5-nitrotetrazole with cuprous chloride suspended in boiling water (reflux) [49, 50]. The addition of acid to the reaction during preparation improves its thermal stability [49]. Recently, Fronabarger et al. improved the preparation procedure by using the more accessible cupric salt as a starting reactant which is reduced to the cuprous salt directly in the reaction mixture. Sodium ascorbate or ascorbic acid is recommended as the reducing agent [68],... 

Preparation of sodium-5-nitrotetrazole dihydrate The diazotization of 5-ami-notetrazole monohydrate (AT) in the presence of excess of sodium nitrite and copper sulfate gives a complex cupric salt intermediate [Cu(NT)2 HNT-4H20] which is then converted to the sodium salt [NaNT-2H20]. 

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