Structure and Preparation
Sodium azide is an ionic solid. Two crystalline forms are known, rhombohedral and hexagonal. The azide anion is very similar in each, being centrosymmetric with NāN distances of 1.18 Ć . The Na+ ion is pentacoordinated.
The common synthesis method is the "Wislicenus process," which proceeds in two steps from ammonia. In the first step, ammonia is converted to sodium amide:
- 2 Na + 2 NH3 ā 2 NaNH2 + H2
The sodium amide is subsequently combined with nitrous oxide:
- 2 NaNH2 + N2O ā NaN3 + NaOH + NH3
Alternatively the salt can be obtained by the reaction of sodium nitrate with sodium amide.
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