Sodium azide, reaction with iron oxide

Earlier, Turrentine (Ref 4) obtained ferric azide in soln by electrolysis of a dil sodium azide soln using iron electrodes and later by Browne et al (Ref 6) on using iron electrodes in liq amm solns of ammonium azide, but the product was ammonolyzed to an Ammono-Basic Ferric Azide. Curtius et al (Refs 1 2), with ferric alum and NaN, obtained ferric azide in soln and they also repotted that iron dissolved in dil aq hydrazoic acid to form the azide, but the soln decompd on evapn giving either the basic azide or hydroxide. In 1934 Franklin (Ref 9) noted that aq hydrazoic acid reacts on iron to form ferric azide, nitrogen and ammonia together with a small amt of hydrazine. According to Franklin Ferrous Azide, Fe(Nj), is formed first and oxidizes to ferric azide when the soln is warmed with excess hydrazoic acid present. Ricca (Ref 11) studied the reactions of the ferric ion with hydrazoic acid on electrolysis of their solns and obtained results which would indicate that ferric azide has the structure [Fe(Nj)](Nj)2... 

MERCURIO (Italian, Spanish) (7439-97-6) Violent reaction with alkali metals, aluminum, acetylenic compounds, azides, boron phosphodiiodide (vapor explodes), bromine, 3-bromopropyne, chlorine, chlorine dioxide, ethylene oxide, lithium, metals, methyl silane (when shaken in air), nitromethane, peroxyformic acid, potassium, propargyl bromide, rubidium, sodium, sodium carbide. Forms sensitive explosive products with acetylene, ammonia (anhydrous), chlorine, picric acid. Increases the explosive sensitivity of methyl azide. Mixtures with hot sulfuric acid can be explosive. Incompatible with calcium, sodium acetylide, nitric acid. Reacts with copper, silver, and many other metals (except iron), forming amalgams. 

A drop of the test solution is placed on filter paper and spotted with a (hrop of a saturated water solution of sodium azide. The fleck is exposed to the vapors of a saturated aqueous solution of sulfurous acid. A yellow color appears which changes to blue on treatment with a drop of a 2 % acetic acid solution of a-tolidine Idn, Limit 0.5 y Co). The test is based on the fact that the oxidation of complex Co azide to complex cobalt azide is catalyzed by the autoxidation of sulfurous acid. The color reaction with o-tolidine is due to the action of the tervalent cobalt formed. Copper and iron ions interfere and should be previously removed or masked. The test can be carried out in the presence of as much as 200 times the amount of nickel. 

---