Nitrotetrazole Salts

The complex disilver 5-amino-l//-tetrazolium perchlorate and nitrate are formed by the reaction of an aqueous solution of silver perchlorate with 5-ATZ in presence of perchloric acid [38], 

Free 5-nitro-l//-tetrazole (subsequently just 5-nitrotetrazole HNT) is an extremely sensitive substance that explodes with the slightest stimulus or even spontaneously [40-42]. However, its metallic salts are stable and heavy metallic salts have the characteristics of primary explosives. 

Free 5-nitrotetrazole forms colorless, extremely hygroscopic, crystals which, if exposed to humid air, dissolve into a simple solution (the material shows strong deliquescence). Melting point of HNT is 101 °C enthalpy of formation is 

CufNTlyHNTTHzO Light blue needles [1] Slightly soluble in wato [44] 

Cu(en)2(NT)2 Violet crystals [4] Slightly soluble in eold watea, readily soluble in hot watea [4] 

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It has been claimed that in contrast with LA, the 5-nitrotetrazole salts possess the advantage of good inflammability even in a moist environment. Their stability is not influenced by the presence of C02 and they may be stored without deterioration in hot climates. Additionally, these compds develop extremely high temps on combustion or expin. If it is desirable to raise the thermic effect, brisance, sensitivity, etc, of the 5-nitrotetrazoles they may be combined with oxygen carriers, combustible substances, abrasives, etc, for use in priming compns. To this end the US Navy is currently proceeding to replace LA with Hg-5-nitrotetrazoIe (Ref 8)... 

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. 

Nitrotetrazole salts have good flammability that is not affected by moisture [45]. Most of them (even the alkaline salts) are powerful primary explosives, e.g., the cesium salt has a performance similar to that of lead azide [42]. 

Klapdtke, M, Sabate, C.M., Welch, J.M. Alkali metal 5-nitrotetrazolate salts prospective replacements for service lead(II) azide in explosive initiators. Dalton Trans. 6372-6380 (2008)... 

An acidified solution of the sodium salt was allowed to evaporate during 3 days and spontaneously exploded 2 weeks later. The nature of the explosive species, possibly the aci-tetrazolic acid, was being sought [1]. The silver and mercury salts are explosive [2], The chemical properties of the free nitrotetrazole have been studied. The sodium salt tetrahydrate loses water above 50°C, greatly increasing its friction and shock sensitivity [3],... 

Given the role that low thresholds of 5-AT and 1H tetrazole impurities clearly play in the successful synthesis of DBX-1 from NaNT, we endeavoured to develop a procedure for synthesizing pure NaNT as efficiently as possible, while avoiding the tedious, time consuming, and reduced yield Cu11 titration and filtration, which is currently required. As an added refinement, we also desired to eliminate the handling of the intermediate acid salt of copper(II) 5-nitrotetrazolate, Cu(NT)2 HNT ... 

Nitrotetrazole is readily prepared from the diazotization of 5-aminotetrazole in the presence of excess sodium nitrite and is best isolated as the copper salt complex with ethylenediamine. The salts of 5-nitrotetrazole have attracted interest for their initiating properties. The mercury salt is a detonating primary explosive. The amine salts of 5-nitrotetrazole are reported to form useful eutectics with ammonium nitrate. ... 

Aminotetrazole (91) reacts with potassium permanganate in excess aqueous sodium hydroxide to yield the disodium salt of 5-azotetrazole (92). 5-Azotetrazole is unstable and attempts to isolate it by acidification yields 5-hydrazinotetrazole (93). Diazotization of 5-aminotetrazole (91) in the presence of excess sodium nitrite yields 5-nitrotetrazole (94), a powerful explosive whose mercury and silver salts are primary explosives. ... 

Nitrotetrazole copper salt 2,4,6-Trinitro-lead-ll-resorcinate... 

Mercuric-5-nitrotetrazole [Structure (2.13)] was prepared according to the methods reported by Gilligan et al. [14] and Redman and Spear [15]. Thus, 5-aminotetrazole was treated with sodium nitrite and copper sulfate to obtain Cu(NT)2HNT-4H20 (where NT nitrotetrazole). The copper salt was subsequently converted to the ethylene diamine complex MNT was then obtained by treating the complex with mercuric nitrate in HN03 medium. The precursors and final product were air dried. The synthesis of these compounds is carried out in a fume hood behind a protective polycarbonate shield in a stainless steel reaction vessel. 

Silver and mercury salts of 5-nitrotetrazole were also investigated as possible replacements for LA and at the end of the investigation, it was concluded that MNT is very effective in small detonators with a superior performance than LA... 

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]. 

The silver(I) salt of tetrazole, Ag(tta), was mentioned by Bladin in 1892 (25) more recently, silver(I) tetrazolates Ag(5-R-tta) have been obtained from silver nitrate and the free tetrazole or 5-substituted tetrazole (78, 94,134). The silver salt of 5-nitrotetrazole, Ag(5-02N-tta),... 

Interest in mercury(II) tetrazolates, notably Hg(5-02N-tta)2, as detonators (12, 190) has prompted thermal decomposition studies on mercury salts of 5-nitrotetrazole (34) and 5,5 -azotetrazole (169). Cycloaddition of methyl isocyanide to Hg(N3)2(PPh3)2 under mild conditions yields the C-bonded tetrazolate complex Hg(l-Me-tta)2 (15). Mercury(II) adducts HgX2(l,5-pmtta) (X = Cl, Br, or CN) and Hg(N03)2(l,5-pmtta)2 have been described (174, 236). 

The salts of 5-Nitrotetrazole could also be ranked according to their sensitiveness. The salts of Ag, Hg, and Pb gave more sensitive compns and greater initiating power than the alkali metal salts. The same salts of 5-Chloro-tetrazole were too sensitive and corrosive, and those of 5-Azidotetrazole were too hazardous (Ref 9b)... 

E. vonHerz (Refs 2 3) first proposed using the w-insol heavy metal salts of 5-nitrotetrazole ie, Ag, Hg and basic Pb, as initiating substances. 

It has been claimed that the initiating power of these salts (when comparing the loading limits) exceeds even that of Pb Azide (LA). This can be seen from the following data which gives the grams required to initiate equal amts of Tetryl LA 0.02, basic Pb-5-nitrotetrazole 0.02, Hg-5-nitrotetrazole 0.006, and Ag-5-nitrotetrazole 0.005g... 

N 21.80% OB to C02 0% pale yel granular crysts mp, detonates at 220°. Sol in hot w si sol in cold w. Prepn is by saturating a hot (80°) 10% soln of free 5-Nitrotetrazole with two milliequiv of Pb peroxide. The mixt is stirred rapidly while hot, and on cooling the product crystallizes out. The basic Pb salt is detonated on impact or friction, being more sensitive to percussion than MF because of its brittleness... 

Kamlet, Improved Method of Preparing the Acid Copper Salt of 5-Nitrotetrazole , PatAppl 794197 (1977) (AD-DOO-4164) 12) DJ. 

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