5,5 -Azotetrazole salts

T able 8.13 Density and water of crystallization contents in one molecule of relevant alkaline and alkaline earth metal salts of AzTZ [89, 91, 92] 

Free 5,5 -azotetrazole forms a yellow solid that is unstable and decomposes within seconds at room temperature. However, it can be handled at —30 °C and stored for several months at —80 °C [89]. 

Most metal salts are yellow (K, Ca, Zn, Pb), while others range from orange (basic lead salt) to brown-colored solids (mercuric, iron) [2, 90, 91]. The cupric salt forms dark green crystals [2]. 

Most metallic salts of 5,5 -azotetrazole form hydrates. The water of crystallization content in these salts is summarized in Table 8.13. During storage of alkaline, alkaline earth metal salts and some trivalent metal salts (Al, La, Y, Ce, Nd, and Gd) all compounds lose water this takes place over a period of hours for lithium, potassium, and the trivalent salts studied, and for other salts it takes between days and weeks. Upon loss of water of crystallization, magnesium and the trivalent salts of AzTZ decompose to colorless substances [89, 91, 92]. The cupric and mercuric salts form anhydrous salts, and the monobasic lead salt (PbAzTZPb0-5H20) forms a pentahydrate [2]. 

According to Bagal [2], the sodium salt forms a pentahydrate at room temperature that loses two molecules of crystalline water above 30 °C and forms an anhydride salt above 75 °C. Contrary to other authors, Reddy and Chatterjee [90] have reported the formation of a monohydrate for the sodium and barium salts (on the basis of TGA results). Lead and mercury salts form as anhydrides [90]. 

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The research in this direction commenced with the studies on materials from the class of azotetrazolates and tetrazines that can be relatively easily isolated [280-284]. The high potential of some nitrogen-rich compounds such as diamino azobistetrazine (DAATz) [Structure (2.65)] [280], 1,4-dihydrazino tetrazine (DHTz) [Structure (2.66)] [281] and azotetrazolate salts [Structure (2.67)] [282-284] has been reported in the literature. The structures of these compounds are shown in Figure 2.4. 

Azotetrazoie (or Bis-5,5 -azotetrazole). See in Voi 1, A659-R to A660-L and the following Addnl Refs 1) H. Morisson, Chemistry of Tetrazole Explosives Derivatives , IntSymp on Utilisation Des Elements Pyrotechniques et Expiosifs Dans Les Systemes Spatiaux , Tarbes (Fr), Dunod (1968) translated by M. Blais, US Army ARRADCOM, Dover (1970) [The impact sensy of various bis-5-azotetrazole salts is presented in Table 7, below... 

The sodium salt of the pentazine derivative (31) can be obtained by treatment of the azotetrazole salt (30) with acid. This reaction has also been used to make some N analogues of (31) (Equation... 

US Army ARRADCOM, Dover (1970) [The impact sensy of various bis-5-azotetrazole salts is presented in Table 7, below... 

The sodium salt of the previously unknown pentazine mesoion (21) has been obtained, as well as some analogues, from treatment of the azotetrazole salt (20) with acid. The compound is unstable and readily loses nitrogen in solution or decomposes, explosively, on heating [93CHE39S]. 

Sensitivity of metallic salts of 5,5 -azotetrazole noticeably depends on the presence of water of crystallization. Upon loss of water, the sensitivity of the compounds to impact and friction increases dramatically [89, 92,95]. For example, the anhydrous sodium salt is highly sensitive to friction and impact while its hydrates are significantly less sensitive. Pentahydrate and trihydrate of sodium salt only crackle after ignition by a Bickford fuse while the anhydrous salt explodes. It is possible to grind the pentahydrate in a mortar while the anhydrous salt explodes with such treatment [2]. Many explosions of 5,5 -azotetrazole salts have occurred during drying under vacuum [89, 92]. 

Salts of azotetrazole (156) are energetic compounds, the guanidinium and methylammonium salts finding use as gas generators when mixed with inorganic oxidizers. Thiele ... 

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. ... 

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)... 

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). 

K. Bahadur, Study of Some Double Salts of Lead Useful as Initiating Explosives by Thermogravimetry and Thermometric Titrations , Symp-ChemProblConnectedStabExpls[Proc], 3rd 1973 (Pub 1974), J. Hansson, Ed, CA 83, 30455 (1975) [The author reports that Lead-5,5 -Diazoaminotetrazolate Styphnate was found to be superior as an initiator expl to other double complexes with azotetrazolic acid or 5-nitra-minotetrazolic acid investigated, and it is recommended as an ideal replacement for Fb Azide... 

Sometimes called diazotetrazoles. Here, usually only 5-azotetrazole, its salts and derivatives are of ordn interest as primary or initiator expls. Two different molecular structures exist which are identified by this nomenclature ... 

Infra-red spectra of the sodium, 1,1r lead, and l,r silver salts of 5,5 -azotetrazole are included] 4) A.T. Thomas R.J. Wiliiams, Fuse Heads , USP 3763783 (1973) CA 80, 17084 (1974) (Electrically initiated (by resistance-wired bridges) fuse heads contg Pb-Azo-tetrazole are claimed in this patent. Thus, typically, sufficient wet Pb-Azotetrazole particles 6—10 microns long and 1—2 microns wide to give 8.08g of dry Pb-Azotetrazole, adjusted to include 2.0g w and 5cc of an aq suspension contg 5% methyl cellulose, is mixed to give a smooth paste. Bridge wires are then immersed in the paste, withdrawn, and the fuse heads so formed are allowed to dry]... 

Tetrazylazoimide and Salts. See in Vol 1, A659-R to A660-L under Azotetrazole ... 

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