Hydrazines tetrazenes

Tetrazane complexes may form as unstable intermediates during the transition metal catalyzed oxidation of hydrazines. Tetrazene adducts are... 

In contrast to the addition products of hydrazines, the interaction of arenediazonium ions with acid hydrazides (Scheme 6-18) yields tetrazenes (6.26), which can be isolated. Tetrazoles (6.27) are obtainable by cyclization (Dimroth and de Mont-mollin, 1910). 

Disubstituted tetrazoles are conveniently prepared from acyl hydrazines (98) and diazonium salts.166 The reaction proceeds through the intermediate tetrazenes (99) followed by cyclization to the tetrazole (100) (Scheme 13). The intermediate can be isolated under mildly basic conditions. Symmetrically 1,2-diacylated hydrazines yield 1-substituted tetrazoles through the elimination of one of the acyl groups.166 - 168 Diformyl-hydrazine is a very convenient starting material for 1-substituted tetrazoles.166, Unsymmetrically 1,2-diacylated hydrazine usually results in mixtures.169... 

One of the oldest-known reactions of N-nitrosamines is their reduction to 1,1-disubstituted hydrazines discovered by Fischer (19) The most common method to perform this transformation has been zinc dust in acid, generally acetic acid tetrazenes are sometimes formed as by-products (20) and denitrosation can also occur. Several other reducing methods have been investigated reduction with lithium aluminum hydride and catalytic hydrogenation are sometimes useful. Sodium dithionite reduction of benzyl substituted N-nitrosamines in base can result in fragmentation to... 

HN N.NH2 Tetrazene (tetrazone, or 2-tetrazene) H2N.N N.NH2 Isotetrazene (1-tetrazene, diazohydrazene, buzylene) HN N.NH.NH2 Ammonium Azide, NH4.N3 Hydrazine Azide,... 

Dinitrobenzene diazo-oxide reacts with hydrazine hydrate to yield 2,4-dinitro-6-[tetrazene-(l)]-phenolhydrazine salt (XIV)... 

Tetrazenes. 1,1-Disubstituted hydrazines (1) are oxidized by this reagent to telrazenes (2) in 75-95% yield.1... 

In the first stage of the reaction an alkoxyl anion and the nitrohydrazine cation are formed which afterwards react together to give the corresponding alcohol and nitrohydrazine. Nitrohydrazine reacts with excess hydrazine to produce tetrazene, nitrous acid and di-imid. Then the tetrazene decomposes to form ammonia and nitrogen from di-imid on the other hand tetrazene, hydrazine and nitrogen are formed. Hydrazoic acid and ammonia are then formed as decomposition products of tetrazene. 

However, the reactivity of 5-hydrazinotetrazole 422 in reactions typical of a hydrazine is poorly documented. An example of the reactivity of some derivatives of 5-hydrazinotetrazole (e.g., 405) in the synthesis of high-nitrogen tetrazole derivatives, such as l,4-bis-[l-methyltetrazol-5-yl]-l,4-dimethyl-2-tetrazene 47, is shown in Scheme 48 <2004MI325>. 

The reaction between aryl azides and lithiated aryl amines leads to tetrazenes, which give cyclic silatetrazenes with halosilanes (equation 7)17. Also, the new mono-, bis- and tris-silylamines 15-28 were obtained18-22. The hydrazine 16 was analyzed by electron and X-ray diffraction18. 

Gaseous 2-tetrazene decomposes only slowly at low pressures to form hydrazinium azide. In solution, 2-tetrazene decomposes above 253 K. It can disproportionate to form dinitrogen and hydrazine or to ammonium azide. 

Tetrazene can be purified by sublimation at 253 K. Tetrazenes with organic substituents can be obtained by oxidation of organically substituted hydrazines. 

Tetrazene is a weaker base than hydrazine and forms salts N4Hs+X with strong acids. The salts decompose at temperatures above 253 K to the respective ammonium salt and hydrazoic acid. 

Organic tetrazenes can be formed in high yield by the oxidation of l,l-bis(organyl)hydrazines R2N—NH2 (31). On the other hand, bis(silyl)hydrazine (31) is converted only indirectly [Eq. (34)] to tetra-kis(silyl)tetrazene (32) (1, 32, 33). The last synthetic step, involving dimerization of azosilane, shows low yield thermally, but high yield (90%) in the presence of the Lewis acid Sip4 as catalyst. 

Strikingly, symmetric tetrazene 52 changes into an asymmetric hydrazine. Possibly, it is not 52 that decomposes into the products given in Eq. (61), but tetrazene 51, which exists in a small equilibrium concentration with 52. 

Diethyltribromobenzene-azohydrazine-dicar-boxylate [called l-(2.4.6-Tribrom-phenyl)-tetrazen-(l)-dicarbonsaure-(3.4)-diathylester or (2.4.6-Tribrom-benzoldiazo)-hydrazin-N.N -dicarbonsaurediathylester in Ger],... 

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