Synthesis of hydrazoic acid

Preparation of hydrazoic acid

Hydrazoic acid is prepared by reacting acids with sodium azide

Preparation of hydrazoic acid

Preparation of hydrazoic acid

To the solution of  sodium azide was added little litmus and poured at 60 ° C sulfuric acid (diluted with water in the ratio 2: 1) with an excess. The hydrazoic acid slowly distills. Multiple fractional distillations lead to 91 % acid which could be obtained anhydrous state by distillation over calcium chloride. However, during the synthesis by this method sometimes occur unusually strong explosions. Relatively safe synthesis could be achieved by replacing sulfuric acid with stearic acid. Sodium azide is mixed with stearic acid in a flask connected directly with trap which is cooled to -40 ° C. Vacuum is applied and the flask heated. Then hydrazoic acid is purified by distillation at a temperature of from – 50 to -80 °C.

Solutions of hydrazoic acid  are more stable and relatively safe.

Water solution of hydrazoic acid

15 g of sodium azide and 5 g of sodium hydroxide are dissolved in 150 ml of distilled water in 250 ml flask. The flask is equipped with a dropping funnel, and efficient condenser. The end of condenser is connected to 500 ml suction flask containing 100 ml of water. The flask contents were heated to the boiling point (this is very important!) and then dropwise 90 ml of 40% sulfuric acid was added. The distillation was continued until the flask is left no more than 50 ml of solution. Thus, a solution containing about 3% hydrazoic acid (0.6-0.7 N) was obtained. Adding sodium hydroxide before the reaction is a precautionary measure that guarantees against the formation of a cold solution of concentrated hydrazoic acid.

Anhydrous ethereal solution of hydrazoic acid:

Since the distribution hydrazoic acid between water and ether determined by the ratio 1:7, hydrazoic acid may be extracted from aqueous solution with ether. However, in this case it is better to use distillation. 30 g sodium azide are dissolved in 100 ml of water and 150 ml of ether was added. The solution was poured into a 500 ml round bottom flask. The flask is equipped with a condenser and corresponding receiver containing 100 ml of ether which is cooled with ice. From a dropping funnel solution of 30 ml of concentrated is added to reaction mixture containing sodium azide, water and ether. A significant portion of ether is distilled with hydrazoic acid already while adding sulfuric acid. The residue was distilled by heating on a steam bath. The ether was dried with calcium chloride and then distilled.

Hydrazoic acid is transparent as water, liquid with boiling point 37 ° C and melting point -80 °C. Anhydrous hydrazoic acid is extreme dangerous. However, solutions, even highly concentrated, are relatively safe. The smell is unbearable sharp. Inhaled following symptoms appear: dizziness, headache, and severe irritation of the mucous membranes.

Руководство по препаративной неорганической химии, Г. Брауэра, 236, 1956 (Guide to preparative inorganic chemistry, H. Brauer,  236, 1956)



InChI Key


Canonical SMILES


MeSH Synonyms

hydrazoic acid

Depositor-Supplied Synonyms

HYDRAZOIC ACID, Hydrogen azide, Triazoic acid, Azoimide, Diazoimide, Hydronitric acid, Stickstoffwasserstoffsaeure, diazonioazanide, UNII-6P5C4D5D7I, CHEMBL186537, 7782-79-8, CHEBI:29449, JUINSXZKUKVTMD-UHFFFAOYSA-N, Stickstoffwasserstoffsaeure [German], EINECS 231-965-8, Hydrazoicacid, hydrogen trinitride(1-), AC1L2NHZ, [NNNH], AC1Q4UY4, 6P5C4D5D7I, CTK2H7516, HSDB 7858, DNC005051, hydrido-1kappaH-trinitrogen(2N–N), LS-77030, FT-0660311, 127229-27-0, 227798-96-1, 57077-96-0

Removed Synonyms

azide, NaN3, CID24530, 14343-69-2, 26628-22-8, HN3, N3H

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