Ammonium azide

The preparation of ammonium azide by the interaction of ammonia with hydrazoic acid in ethereal solution has been described by Frierson. A second preparative method using ammonium nitrate or sulfate is also described in the same reference. Both methods have disadvantages, in that the former requires the preparation of hydrazoic acid, whereas the latter is limited to small quantities because of explosion hazards. 

Two German patents by Muller describe preparative methods which avoid the use of hydrazoic acid by heating sodium azide with ammonium chloride or sulfate in aqueous solution. A recent Japanese patent describes a reaction between sodium azide and ammonium carbamate in liquid ammonia to give ammonium azide. Evans, Yoffe, and Gray have suggested the reaction of sodium azide with ammonium chloride in iV,iV-dimethylformamide. A modification of the last method has been made it involves the reaction of sodium azide and ammonium sulfate in dimethyl-formamide to give anhydrous ammonium azide of high purity. 

Caution. Although this procedure has been repeated many times without requiring fecial precaution s, it is essential that 

The apparatus is assembled as shown in Fig. 1. All connections and joints exposed to the corrosive hot vapors of 

The stopper is cut off the lower leg of the Dean-Stark trap, leaving the tube with an opening of about 5 to 6 mm. To the end of this tube is connected a suction flask F by means of a short rubber tube. Flow through the tube is controlled by means of a pinch clamp E. A vacuum connection is made through trap K, which is cooled by an ice-salt mixture. The pressure in the system is determined by means of the mercury-filled manometer J. 

This compound, of the interesting empirical composition N4H4, has the properties of a typical ammonium salt. At 20°C, 100 ml water dissolve 20.16 g 100 ml methanol, 3.27 g and 100 ml ethanol, 1.06 g [47]. It is easily recrystallized from hot methanol or precipitated with ether. 

Like ammonium chloride, N4H4 dissociates thermally below the melting point according to NH4N3 HN3 +HN3, but the tendency here is so pronounced that the vapors are completely dissociated at room temperature [302], and the substance volatilizes quickly when left uncovered [1,62]. 

The thermal dissociation of N4H4 is frequently mistaken for sublimation. It has been reported with a note of surprise, for example, that the salt explodes when heated in a sealed system, but not in open air [303,304]. These explosions stem from a pressure build-up of free HN3 in the vapor phase (see hydrogen 

N4H4 is made by simple metathetic reaction in liquid, solid, or gaseous media which may involve distillation or precipitation. For example, equimolar amounts of ammonium chloride and sodium azide may be distilled with an equal quantity of water. At 160°C pot temperature, the product volatilizes with water vapors and solidifies in the condenser tube which should, therefore, be at least 1 inch wide [305]. Equally clean and safe is a gas-phase reaction which requires, however, the preparation of hydrazoic acid gas. The reaction takes place in a long, 1-inch-wide glass tube which has two inlet tubes with orifices 20 inches apart, and a vent. The HN3 gas, carried with nitrogen, and excess ammonia stream in and precipitate the product as fine needles [39]. N4H4 is also precipitated when ammonia gas is bubbled into an ethereal hydrazoic acid solution [86]. The product stays in solution when HN3 vapors, carried with nitrogen, are bubbled into aqueous ammonia [306]. 

The following procedures have also been reported as advantageous, but are in fact inferior Larger batches were made by mixing equimolar amounts of sodium azide and ammonium acetate as saturated solutions upon cooling to 5°C, N4H4 separated in low yield (approx. 25%). Additional crystallizations from the mother liquor were contaminated with sodium acetate [307]. Or, a distillation method uses dimethylformamide as a vehicle to react and distill sodium azide and ammonium sulfate. The procedure is cumbersome because clogging of the condenser could not be controlled satisfactorily, in spite of elaborate equipment [308]. Not recommended is a dry method in which sodium azide and ammonium nitrate are heat treated, and the product is sublimed off at 200°C. The vapor phase contains free HN3 which tends to explode above room temperature (see p. 25). Reportedly, 5-g batches were made safely, but a 50-g batch exploded at 158°C [303]. 

Small pellets of NH4N3 sublime in an inert atmosphere below 523 K [1003]. At higher temperatures and/or pressures, there is slow decompo- 

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N4H4 rra 5-2-tetrazene, H2N-N=N-NH2, (colourless, low-melting ciystals, N-N 143pm, N=N 121pm). and ammonium azide, NH4N3 (white ciystals, subl. 133°C, d 1.350gcm 3)... 

See Quaternary ammonium azides, below Sodium azide, below... 

Quaternary ammonium azides will displace halogens in a synthesis of alkyl azides. Dichloromethane has been used as a solvent, although this can slowly form diazido-methane which may be concentrated by distillation dining work-up, thereafter easily exploding [1]. An accident attributed to this cause is described, and acetonitrile recommended as a preferable solvent, supported polymeric azides, excess of which can be removed by filtration are also preferred in place of the tetrabutylam-monium salt [2]. A similar explosion was previously recorded when the quaternary azide was generated in situ from sodium azide and a phase transfer catalyst in a part aqueous system [3,4],... 

Evaporation of a solution of hexachloroplatinic acid with a deficiency of potassium azide, or with an equivalence of ammonium azide gives explosive residues. Evaporation of a solution of the acid with an equivalence (8 mol) of potassium azide leads to explosion of the cone, solution of the title compound. 

This primary explosive is created by adding lead acetate to a solution of sodium or ammonium azide. Lead azide has a good shelf life in dry conditions but is unstable in the presence of moisture, oxidizing agents, and ammonia. It is less sensitive to impact than mercury fulminate, but more sensitive to friction. Since lead azide is a nonconductor, it may be mixed with flaked graphite to form a conductive mixture for use in low-energy electronic detonators. 

Amino-4//- 1,2,4-triazole, 0812 Ammonium azide, 4526 Azidoacetonitrile, 0714 Azido-2-butyne, 1473... 

Aluminium tetraazidoborate, 0059 Ammonium azide, 4526 Azidodimethylborane, 0888 Azidoiodoiodonium hexafluoroantimonate, 4361 Azidosilane, 4501... 

The synthesis of aryloxysulphonyl azides, which can be used as precursors for sulphamates, is improved by the use of tetra-n-butylammonium azide under homogeneous conditions in place of an alkali metal azide [ 1 ]. A stoichiometric amount of the ammonium azide is used and no attempts appear to have been made to conduct the reaction under solid liquid phase-transfer catalytic conditions. 

Darensbourg and coworkers reported a systematic investigation of ROP catalyst performance along with kinetic and mechanistic studies for the polymerization of L- and rac-lactide using calcium complexes derived from tridentate Schiff base ligands (Fig. 13) [90, 91]. With calcium catalysts 77a-d, used in melt and solution polymerization of L-lactide, it was found that calcium salen catalyst 77d with bis (phosphoranylidene)ammonium azide as a co-catalyst is much less active than the calcium complexes with tridentate Schiff base ligands, as reflected in the monomer L-lactide conversions of 59-80% for 77a-c but only 35% for 77d as initiator. 

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,... 

Octazotriene (octazone) HN N.NH.N N.NH.N NH Many of the derivatives of the above compounds are explosive and they are described separately under corresponding names. Some of the compounds included in these tables (as for instance ammonium azide and hydrazine azide), do not possess the structural formula of real hydronitrogens but they are included for the sake of comparison, because their empirical formulas correspond to the type NnHn.2 Refs 1) L.F. Audrieth B.A. Ogg, TTie Chemistry of Hydrazine , J. Wiley, NY (1951), p 3-6 2) C.C. Clark, Hydrazine , Mathieson... 

Ammonium azide Ammonium nitrate Ammonium nitrate Ammonium nitrate Ammonium nitrate... 

Figure A.21 Ammonium azide primary high explosive.

A number of investigations have been devoted to the thermal decomposition of hydrazoic acid or to decomposition produced by electric discharge. Thus Rice and Freamo [50] established that its thermal decomposition at 77°K leads to the formation of a blue-coloured sediment. At a higher temperature, 148°K, it changes colour, forming a white substance which has been identified as ammonium azide. They suggested that the blue colour is caused by the presence of the free imino radical NH. 

According to Alekseyev [62] explosion of a mixture of HN3 and hydrogen gives ammonium azide and the intermediate compound N2H5N3. 

Curtius [1] who prepared ammonium azide did not notice its explosive properties. They were reported by Berthelot [139] who found ammonium azide to be an endothermic substance with a heat of formation — AH( of —19.0 kcal. 

Berthelot and Vieille [140] reported that the explosive decomposition of ammonium azide proceeds according to the following equation ... 

A low explosion temperature together with a great amount of gaseous products and a high specific pressure suggested the used of ammonium azide as a propellent explosive. In practice the use of the substance, however, is prevented by its high volatility. 

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