A New Synthesis of Lead Azide

LEAD azide is still prepared by using, in principle, a method first described by Curtius1. This method involves reacting a soluble inorganic azide, preferably sodium azide, with a soluble lead salt, preferably lead nitrate or lead acetate, in aqueous solution whereby lead azide is formed as a precipitate. The precipitate is always contaminated with the cation coming from the azide and the anion coming from the lead salt. Purification by recrystallization is difficult for the following reasons: The solubility of lead azide in pure water is very small. Using an ammonium acetate solution in which the solu bility is higher introduces new impurities. Furthermore, lead azide has a tendency to detonate spontaneously on recrystallization2. A direct synthesis of lead azide from lead oxide and hydrazoic acid yields inhomogeneous yellow products because the lead azide formed on the surface of the lead oxide grains is very insoluble and prevents further reaction.