Hydrazoic acid, from decomposition

The first-order decomposition rates of alkyl peroxycarbamates are strongly influenced by stmcture, eg, electron-donating substituents on nitrogen increase the rate of decomposition, and some substituents increase sensitivity to induced decomposition (20). Alkyl peroxycarbamates have been used to initiate vinyl monomer polymerizations and to cure mbbers (244). They Hberate iodine quantitatively from hydriodic acid solutions. Decomposition products include carbon dioxide, hydrazo and azo compounds, amines, imines, and O-alkyUiydroxylarnines. Many peroxycarbamates are stable at ca 20°C but decompose rapidly and sometimes violently above 80°C (20,44). 

The slow, thermal decomposition of hydrazoic acid in a static system has been studied by Meyer and Schumacher58. It turned out to be completely governed by heterogeneous catalysis. There are no studies on the kinetics of the homogeneous decomposition of this substance save for the investigation of its decomposition flame59. From the variation of flame properties with pressure it can be deduced that second-order reactions control the over-all rate. The unimolecular reaction... 

Using Norrish s flash photolysis method [54], Thrush [55] examined the decomposition of hydrogen azide in the presence of an excess of inert gas. The absorption spectra characteristic of the radicals NH and NH2 were observed. He therefore suggested an alternative scheme for the decomposition of hydrazoic acid, different from that proposed by Beckmann and Dickinson [56] ... 

The formation of hydrazoic acid and its derivatives together with ammonia from diazo compounds under the influence of hydrazine or its derivatives was explained by Thiele [68]. At an intermediate stage a diazohydrazine, e.g. C6H5N2NHNH2, is formed which then undergoes decomposition according to two parallel reactions ... 

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. 

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. 

Dr. Rudolf Meyer was born on 4. 3. 1908 in Spandau (Berlin) and took his degree in Physical Chemistry. He began his initial studies in the area of energetic compounds in connection with his Doctor s degree in 1931 at Professor Boden-stein s Institute in Berlin with a paper on the enthalpy of formation and thermal decomposition of hydrazoic acid. After taking his Doctor s degree, he entered the Dynamit Nobel Company in 1934 as assistant to Dr. Ph. Naoum. He worked there from 1936-1945 on the development of pourable ammonium nitrate explosives and on hollow charges. 

Hydrazoic acid is conveniently prepared in situ by hydrolysis of azidotrimethylsilane over silica gel. Only a catalytic amount of trifluoromethanesulfonic acid is required to achieve the hydroazidation of cyclic alkenes the completion of the reaction is preferentially controlled by gas-chromatographic analysis, as prolonged reaction time causes the partial decomposition of the organic azide by the acid catalyst. From norbornene the exo-azide 5 was exclusively produced, but no diastereoselectivity was observed with 1,2-dimethylcyclohexene106. 

The intramolecular aziridination of alkoxycarbonyl azides derived from ( )-5-hydroxymethyl-2(5//)-furanone, via thermal decomposition to nitrenes, gave the tricyclic compound 34 which was successively converted to the bicyclic compound 35. The aziridine ring opening with hydrazoic acid/ sodium azide ion of the aziridines 34 and 35 gives azido lactones 36 with the xylo configuration mixtures of xylo- and (y.w-forms were obtained by partial epimerization in equilibrating conditions and were easily separated60. 

In a much poorer yield, compound (8) was the product from the thermal decomposition of 5-(2-pyridyl)tetrazole (305) at 400°C/10 Torr (78HCA1755). Compound (305) was prepared by treating pyridine-2-carbonitrile with hydrazoic acid. [l,2,3]Triazolo[l,5-a]pyridines are also the products from the treatment of 1-aminoquinolizinium salts (306a) with nitrous acid in a process proceeding via (306b) (69TL1549). 

Recently, a series of papers has been published concerning the Schmidt reaction of / -quiriones , and the acid-catalysed decomposition of azidoquinones " . The Schmidt reaction of various p-quinone derivatives gave rise to substituted 2,5//-2,5-azepindiones in yields ranging from 75-85% . For example, 3,4-benzo-6-methyl-2,5-azepindione (73) was obtained from the reaction of hydrazoic acid with 2,3-benzo-5-methyl-l,4-quinone (69) in concentrated sulphuric... 

The reaction was discovered in 1923 in interesting circumstances. Products from the decomposition of hydrazoic acid in various solvents were investigated and the decomposition catalysed by sulphuric acid in benzene was found to lead to aniline Schmidt considered an imine radical NH to be the species responsible and on attempting to trap this with benzophenone he obtained benzamide. The reacdon was generalized and rapidly exploited, mainly by its discoverer. The currently accepted mechanism was proposed in outline shortly after-wards and is shown in its modern form in scheme (19) for carboxylic... 

Tlie formation of free radical HN by decomposition of hydrazoic acid has been suggested by a number of authors since 1928 (see Vol. HI, p. 167). This was substantiated by experiments on the decomposition of HNj by the flasli photolysis of Thrush (Vol. Ill, p. 167). The formation of nitrene radicals from azides by flash photolysis was reported simultaneously and independently by Koto (56], Reiser et al. [57—59]. Reiser rationalized the reaction derived from flash pl otolysis of formation of azo compounds (5) ... 

The hydrazoic acid resulted from the hydrolysis reaction. Iron in contact with the slurry resulted in 40% decomposition of the lead azide within 90 days, and iron held in the gas phase above the lead azide slurry resulted in 70% destruction of the lead azide within 90 days. The alcohol-water solution turned dark red-brown, and the iron oxidized when the capsule was opened. The hydrazoic acid and ammonia concentrations inside and outside the polyethylene bags were the same. There was spectrophotometric evidence for the [Fe(N3)2] complex. 

In the soil, azides are not degraded microbiologically but purely chemically, according to the two different mechanisms shown above. In acid soil and with adequate humidity, the main route of decomposition is the formation of hydrazoic acid. The highly volatile acid rapidly volatilises from the soil (Ketchersid and Merkle, 1976). Alkalinity of soil and the admixture of cyanamide to the azide increase the herbicidal efficiency and persistence (Danielson, 1965 Colby and Freemy, 1967). 

I rifications of crystalline lA and IIA metal azides were commonly conducted by repeated recrystallization from water, or reprecipitation with organic solvents. These operations are ineffective, however, at least with respect to soluble impurities which usually precipitate together with the azide. In fact, one can argue that additional impurities were likely introduced with the organics or by hydrolytic decomposition of the azides, unless the latter was checked by repeated replacement of the evaporating hydrazoic acid. These facts went largely unnoticed, mainly because the need for establishing impurity profiles after the purification was not seen or because analysis was performed with inappropriate methods. 

The above preparations in aqueous media incorporate some unavoidable hydrolytic decomposition (therefore recrystallization from hydrazoic acid), which is reduced in alcohol media. For example, lithium chloride [82] may be... 

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