Aminotetrazole salts

5-Amino-l//-tetrazole (subsequently just 5-ATZ) was first synthesized by Johannes Thiele in 1892. He obtained this compound by cyclization of azidoformamidme in a boiling aqueous solutimi [28, 29]. 

Free 5-ATZ contains the acidic tetrazole ring and the basic amino group. Its chemical behavior is similar to that of amino acids. Free 5-ATZ forms a monohydrate that loses water of crystallization above 100 C. The melting temperatore of 5-ATZ is 203 °C [2]. This compound is very hygroscopic, soluble in hot water, acetone, and ethanol [1,2]. 

Most metalUc salts of 5-ATZ are soluble in water as well (except the silver, cupric, and mercurous salts). Many metallic salts form various hydrates [1], The sodium salt forms yellow crystals, crystallizes with three molecules of water of crystallization and is soluble in water [2], Some physical properties of heavy metallic salts are summarized in Table 8.2 [30]. 

Pb(ATZ)2 Colorless Precipitated with acetone from water 

Most metallic salts of 5-ATZ are not typical primary explosives. Similarly to free 5-ATZ, the sodium salt is not sensitive to impact [2] and even the sensitivity to impact of heavy metal salts is relatively low in comparison with common primary explosives (see Table 8.3). 

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See 5-Aminotetrazole Nitrous acid See other DIAZONIUM SALTS, TETRAZOLES... 

Diazotised 5-aminotetrazole is unstable under the conditions recommended for its use as a biochemical reagent. While the pH of the diazotised material (the cation of which contains 87% nitrogen) at 0°C was being reduced to 5 by addition of potassium hydroxide, a violent explosion occurred [1], This may have been caused by a local excess of alkali causing the formation of the internal salt, 5-diazoniotetrazolide, which will explode in concentrated solution at 0°C [2], The diazonium chloride is also very unstable in concentrated solution at 0°C. Small-scale diazotisation (2 g of amine) and susequent coupling at pH 3 with ethyl cyanoacetate to prepare ethyl 2-cyano-(l//-tetrazol-5-ylhydrazono)acetate proceeded uneventfully, but on double the scale a violent explosion occurred [3], The importance of adequate dilution of the reaction media to prevent explosions during diazotisation is stressed [4]. 

The reaction sequence starts from tetrazolyldiazonium salt 42 prepared from aminotetrazole 41 by diazotation. This compound when reacted with arylformylacetonitrile 43 leads to the intermediate formation of the condensation product 44, which easily undergoes ring closure to 45. This tetrazolo[5,l-z][l,2,4]triazine compound, however, forms an equilibrium with the valence bond isomeric azide 46, which can participate in a different ring closure than the reverse route, and yields the tetrazolo[l,5-A][l,2,4]triazine product 47. The reaction was carried out with a series of various aryl derivatives and proceeded in good to excellent yields (68-87%). 

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. ... 

Treatment of the bis(pyrazoyl)tetrazine (197) with an excess of hydrazine hydrate generates 3,6-bis(hydrazino)-l,2,4,5-tetrazine (208), a compound which might find use as an energetic additive in high performance propellants. Several salts of (208) have been reported, including the dinitrate and diperchlorate. 3,6-Dichloro-l,2,4,5-tetrazine (209), the product from treating (208) with chlorine in acetonitrile, reacts with the sodium salt of 5-aminotetrazole (210) to yield (211) (C4H4N14 - 79 % N). ... 

The reaction of aminoguanidine bicarbonate (84) with sodium nitrite in the presence of excess acetic acid produces 1,3-ditetrazolyltriazine (89), another nitrogen-rich heterocycle (C2H3N11 = 85 % N) which readily forms explosive metal salts. The reaction of aminoguanidine bicarbonate (84) with sodium nitrite in the presence of mineral acid yields guanyl azide (90), of which, the perchlorate and picrate salts are primary explosives. Guanyl azide (90) reacts with sodium hydroxide to form sodium azide, whereas reaction with weak base or acid forms 5-aminotetrazole. ... 

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. ... 

The ditetrazolium salts (309) have been patented for use in electrochromic electrodes which are used in display devices <89JAP01230026) and tetrazolium salts have also been developed for cell bioassays for neurotoxins active on voltage-sensitive sodium channels <93MI 417-03). Tests for inhibition of corrosion of zinc and brass carried out on 5-aminotetrazole showed it to be ineffective relative to other azoles <86MI 417-01). A number of tetrazoles including the 5-amino, 5-methyl, and 5-phenyl derivatives have been separately incorporated into surfactants used for corrosion inhibition with copper in water <9lMl4l7-07). Photopolymerizable resin compositions which are highly resistant... 

Halotetrazole Salts. The hazards heretofore encountered in the prepn of halotetrazoies have been eliminated, and a safe method for diazoti-zing 5-aminotetrazole has been devised. Several salts of halotetrazoies were prepd, and aside from results of practical importance such as the production of compds of interest as initiator materials, this work may give rise to some important theoretical consideration as to the fundamental chemistry of initiators... 

Azotetrazole was prepd by J. Thiele, and its expl salts were recommended by E. von Herz and by H. Rathsburg for use in detonators. Its derivatives were described by L.F. Aufrieth J.F. Currier in Umv of Illinois Kept, Derivatives of 5-Aminotetrazole , pp 22—23 (1954) (See Vol 1 of Encycl, pp A659 A660)... 

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. 

I, 4-Dimetbyl-5-iminotetrazole, crysts (from benz), mp 108.5-09 5° was obtd by saturating with anhyd K carbonate the aq filtrate from the HC1 salt resulting from the methyl-ation of l-methyl-5-aminotetrazole. Also prepd were its Picrate, fine ndls (from 95% ale), mp 211.5-12.5° dec Hydrochloride, long thin ndls (from 90% isopropyl ale), mp 242-44° dec and Hydrobromide, crysts (from abs ale), mp dec 190-91°(Ref 2)... 

Reaction of bis(2,4,6-trichlorophenyl)malonates (624) with 5-aminotetrazole in the presence of Et3N yielded the ammonium salts 625. Upon treatment of 625 with strong acids, a mixture of 626 and the 2-azidopyrim-idines (627) was obtained (93JHC1267) (Scheme 125). 

This substance forms salts with acids, and was first isolated in the form of its nitrate. The nitrate is not detonated by shock but undergoes a rapid decomposition with the production of light when it is heated. The picrate and the perchlorate explode violently from heat and from shock. Guanyl azide is not decomposed by boiling water. On hydrolysis with strong alkali, it yields the alkali metal salt of hydrazoic acid. It is hydrolyzed by am-moniacal silver nitrate in the cold with the formation of silver azide which remains in solution and of silver cyanamide which appears as a yellow precipitate. By treatment with acids or weak bases it is converted into 5-aminotetrazole. 

When the reaction between aminoguanidine and sodium nitrite occurs in the presence of an excess of acetic acid, still another product is formed, namely, 1,3-ditetrazolyltriazine, the genesis of which is easily understood from a consideration of the reactions already mentioned. 5-Aminotetrazole is evidently formed first the amino group of one molecule of this substance is diazo-tized by the action of the nitrous acid, and the resulting dia-zonium salt in the acetic acid solution couples with a second molecule of the aminotetrazole. 

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