Preparation of Azides

Only those azide syntheses are treated below that involve formation of an N-N bond, namely  

Alteration of nitrogen groups in carbon-nitrogen compounds 

Phenyl azide from benzenediazonium perbromide and ammonia 262 A 21 % solution (15 ml) of ammonia is covered with a layer of ether (10 ml) and to it is added, with ice-cooling and good stirring, the diazonium perbromide (4.05 g) in small portions a surface reaction between the perbromide and the ammonia leads to immediate and quantitative production of phenyl azide which is taken up by the ether phase. Then the ether is evaporated and the two-phase residue is subjected to steam-distillation. The distillate, which contains ammonia, is acidified with dilute sulfuric acid, and the phenyl azide is extracted in ether and then distilled in a high vacuum into a receiver cooled in solid carbon dioxide. The yield is 55 % (0.775 g). 

The diazonium perbromide is prepared as described in Gattermann and Wieland s book.lf 

Phenyl azide from phenylhydrazine and nitrous acid 263 Very pure phenylhydrazine (33.5 g) is added in 10 min, dropwise and with stirring and cooling in ice-salt, to a mixture of water (300 ml) and concentrated hydrochloric acid (58.5 ml). Whilst stirring is continued, the solution is covered with ether (100 ml) at 0° and a freshly prepared solution of sodium nitrite (25 g) in water (30 ml) is dropped in slowly (20-30 min) at a rate such that the temperature does not exceed 5°. The mixture is then distilled in steam (400 ml collected), the ether layer is separated, and the aqueous phase is extracted with ether (28 ml). The ether layers are combined, dried over calcium chloride (10 g), and distilled under reduced pressure in the water-bath (26-30°) the phenyl azide is distilled off cautiously at 65° (bath-temperature)/5 mm it has b.p. 49-50°/5 mm the yield is 24-25 g (65-68%). 

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Phase transfer conditions are used as well for the preparation of azides.73... 

Tetramethylguanidinium azide, an azide salt that is readily soluble in halogenated solvents, is a useful source of azide ions in the preparation of azides from reactive halides such as a-haloketones, a-haloamides, and glycosyl halides.74... 

There are also useful procedures for preparation of azides directly from alcohols. Reaction of alcohols with 2-fluoro-l-methylpyridinium iodide followed by reaction with lithium azide gives good yields of alkyl azides.75... 

A separate preparation of azides is not always necessary. Scheme 183 illustrates a case where azides are generated in situ from the corresponding halides. The reactions are carried out in ionic liquid-water system. Triazole 1117 is obtained in 94% yield from a reaction carried out at room temperature for 4h. Butyl derivative 1118 is obtained in 90% yield under similar conditions <2006TL1545>. 

Hassner et al. (8) reported a novel synthesis of 2,5-dihydroxyoxazoles (32) using an intramolecular azide-alkene cycloaddition. The ratio of reagents (aldehyde/allyl alcohol/hydrazoic acid, 1 3 9) was critical for the preparation of azide 30 (Scheme 9.8). 

The preparation of azides using other acid halides follows a procedure similar to that for o-nitrobenzenesulfonyl azide with the exception that drop-wise addition is recommended. 

A similar strategy in aqueous media has now been applied to the nucleophilic substitution of alkyl halides or tosylates using readily available alkali azides, thiocyanates or sulfinates under microwave irradiation. The approach afforded safe and efficient preparation of azides, thiocyanates and sulfones (Scheme 23) (Ju et al., personal communications). 

CHAPTER 5 THE PREPARATION OF AZIDES AND AZO NITROS consult any protected commercial or industrial processes related to, similar to, or additional to, the process discussed in this procedure. This process may be used to legally prepare the mentioned explosive for laboratory, educational, or research purposes. 

CHAPTER 5 THE PREPARATION OF AZIDES AND AZO NITROS this procedure. These compounds can be isolated using various techniques, but these techniques will not be discussed here as they deviate from the procedure. 

CHAPTER 5 THE PREPARATION OF AZIDES AND AZO NITROS Afterwards, cure the granules for several days at room temperature before use. After which, the granules can be packed into gun casings. Note Do not use a blasting cap or detonator for initiations. 

Table 16. Preparation of azides by the diazo transfer reaction...

Some substances, including impurities, enhance the decomposition of azides. The impurities can be present in the course of preparation of azides or formed during their storage. It is known that the presence of carbon dioxide in air may produce a decomposition of lead azide. Also water vapour in air even at rcoin temperature may accelerate (he decompr>sition. fhis problent was tackled by. Reitzner (115]. He found that the induction period was the result of the re-laction of water vapour with lead. 

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