Azides of Copper

All copper azides explode, but the sensitivities vary widely. It is extremely high in the normal azides, Cu(N3) and Cu(N3)2. At the other end of the scale are almost insensitive azido complexes of large organic cations. In general, a copper azide is more sensitive than the respective lead azide. 

Copper azides are formed with relative ease when copper or brass are in contact with moist hydrazoic acid vapors or solid metal azides. This behavior creates a particular safety hazard, and hardware containing copper or brass cannot be tolerated in the vicinity where azides are prepared or stored. Further details are discussed in Chapter 3, Volume 2. 

Cu(I) azides are photosensitive, and both the Cu(I) and azide groups appear to react independently. In addition, Cu is oxidized when exposed to atmospheric oxygen. The normal Cu(I) azide, Cu(N3), is a white, crystalline solid. On account of its reactivity, however, it is usually obtained as a gray-green powder [175]. Exposure to light leads soon to a dark red product [1] while nitrogen is evolved [175]. The compound is insoluble in water and organic solvents. It is extremely sensitive to heat (temperature of explosion, 220°C [176], impact, and friction. 

powdery CuNa is obtained as an intermediate when copper metal is allowed to stand under hydrazoic acid for several days. Further exposure leads, after some weeks, to Cu(N3)2. CuNa is further obtained by reduction of copper(II) azide  

The reduction takes place in aqueous media by gentle heating with hydrazine or in alcohol by heating with hydroxylamine [181]. 

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