Synthesis of sodium azide

Preparation of sodium azide

Preparation of sodium azide from n-butyl nitrite and hydrazine hydrate

Forty to forty-three grams of sodium hydroxide are dissolved in 500 ml of absolute ethyl alcohol by warming. The solution is cooled and either filtered through a sintered glass funnel or decanted to remove insoluble impurities. To the clear filtrate in a one-liter flask fitted with a reflux condenser (a ground-glass type is preferable) are added 60 g of 85 % hydrazine hydrate. The mixture is warmed gently on a steam bath and then 15 g of freshly distilled n-butyl nitrite are added through the condenser. The steam bath is removed and then 110 g more of n-butyl nitrite are added as before at such a rate that spontaneous refluxing is maintained. The sodium azide precipitates during the procedure. To ensure completion of the reaction the flask and contents are heated 15-30 minutes after the addition. After cooling in ice, the sodium azide is suction-filtered and washed, first with four 25 ml portions of ice-cold absolute alcohol, then with two similar volumes of ether. The white salt is dried in warm air yielding 50-55 g of sodium azide.

Inorganic laboratory preparations, by G. G. Schlessinger, 28-29, 1962

Preparation of sodium azide from sodium amide and nitrous oxide

Preparation of sodium azide from sodium amide and nitrous oxide

Preparation of sodium azide from sodium amide and nitrous oxide

One and one-half grams of clean sodium are placed in a boat and inserted into a combustion tube mounted in a cir­cular furnace. Bone-dry ammonia is passed through the apparatus which is heated to 350°C and maintained at this temperature for one-half hour. The tube is cooled in an atmosphere of ammonia. Nitrous oxide (either from a cylinder or from 20 g of ammonium nitrate by gentle heat­ing) which has been carefully dried by passage through two soda-lime and two sodium hydroxide U-tubes in series, is passed over the sodium amide at 190° C until vapors of ammonia are no longer evolved. If ammonium nitrate is used as thee source of the gas, it is necessary to insert a vertical water-cooled condenser between the generator and the first drying tube to remove most of the water formed.

The sodium azide, mixed with the sodium hydroxide, is dissolved in 20 ml of water contained in a 50 ml distilling flask which is fitted with a condenser and a dropping funnel. The con­denser leads into a small filter flask containing 10 ml of water. The solution is heated to the boiling point so that distillation just begins and then 15 ml of 40% sulfuric acid are added drop by drop from the funnel. The distillation is continued until about five ml of liquid remain in the flask.

One millilitre of the aqueous distillate of hydrazoic acid is reserved and the remainder is exactly neutralized with 1N sodium hydroxide. The solution is evaporated to crystal­lization, then cooled, and the reserved hydrazoic acid is added to it. A volume of 95% ethanol double the volume of the contents of the dish is added to precipitate the sodium azide, the mixture is cooled in ice until no more crystals settle out, then suction-filtered, washed with ether and finally dried in vacuo yield 1.5-1.8 g of sodium azide.

Inorganic laboratory preparations, by G. G. Schlessinger, 28-29, 1962

Preparation of sodium azide from ethyl nitrite and hydrazine hydrate or hydrazine sulfate

5 g of hydrazine hydrate are dissolved in 50 ml of ether. The solution is cooled with ice, 37.5 ml of 4N sodium methoxide solution and 12.6 ml  ethyl nitrite are added. The reaction solution is allowed to stand for some time on ice, then slowly brought to room temperature. The crystals of NaN3 are filtered and washed with a mixture of methanol and ether.

If no hydrazine hydrate is available, sodium methoxide can mixed with a corresponding amount of hydrazine sulfate, then filtered and the separated from  sodium sulfate solution.  The obtained hydrazine hydrate is treated with ethyl nitrite and NaN3 is separated as described above.

Finally, it is also possible to obtain sodium azide by dissolving 26 g of hydrazine sulfate in 140 ml of sodium hydroxide solution containing 28 g NaOH and 22 ml of ethyl nitrate. The mixture is shaken in a thick-walled sealed flask for 6 hours. Unreacted ethyl nitrite is evaporated with the current of air. The alcohol is removed in a water bath by passing air, and the solution was used directly for the preparation of hydrazoic acid.

Sodium azide is colorless crystals. When heated, it decomposes into nitrogen and sodium. Solubility at 17° C: 42 g in 100 g of water; 0.3 g in 100 g of alcohol.

Руководство по препаративной неорганической химии, Г. Брауэра, 237, 1956 (Guide to preparative inorganic chemistry, H. Brauer, 237, 1956)

Preparation of sodium azide directly from sodium via sodium amide

100 g of metallic sodium are placed in a nickel dish and heated in the iron can, to a temperature of about 350° C (during this process the temperature must not be allowed to fall below 250° C) in a current of pure ammonia gas, that is first dried by passing it through soda-lime and fused sodium hydroxide.

A glass apparatus for the preparation of sodium amide

A glass apparatus for the preparation of sodium amide

The can A is of sheet iron and is provided with a double bot tom and with a grooved top, K K’, into which fits the cover B. This has three tubular openings, H, H’, H”, for rubber stoppers holding respectively the inlet tube for ammonia D, the outlet tube E, and the thermometer F. The nickel dish G stands upon a little tripod which prevents direct contact between the dish and the highly heated bottom. The can is placed upon a thick iron plate, and heated with a triple burner. The inlet tube, through which the ammonia enters, is pushed down beneath the surface of the sodium as soon as that metal melts so that the gas may bubble up through the liquid. When the reaction is nearly complete (from five to seven hours) the inlet tube is raised out of the liquid. The flow of ammonia gas should be steady to prevent the rise of sodium in the inlet tube. In any case it is well to guard against the danger due to sudden stoppage by providing the inlet tube at some point outside of the iron can with a perpendicular side tube dipping into mercury. The end of the reaction is shown by the absence of hydrogen in the gas escaping from the can. Hydrogen in this escaping gas may be detected by collecting the gas in a test-tube by displacement, closing the tube with the thumb and immersing the mouth of the tube in water to absorb the ammonia, and then bringing the residual gas in the test-tube into contact with a flame. When no inflammable gas is present in the tube, the operation may be regarded as complete. The apparatus is then allowed to cool nearly to the temperature of the room. It has been found inadvisable to treat all of this product in one operation with nitrous oxide because of the tendency to “creep,” shown by the sodium azide. Consequently, about threefourths of the sodium amide resulting from the above operation is removed and placed in a desiccator over metallic sodium. The iron can containing the remainder of the sodium amide in the nickel dish is now connected with an apparatus furnishing dry nitrous oxide, the arrangement being that shown bellow:

A glass apparatus for the preparation of sodium azide

A glass apparatus for the preparation of sodium azide

Nitrous oxide gas is made by heating ammonium nitrate. The ammonium nitrate is contained in the flask A resting on an iron plate and heated by a single Bunsen burner. The outlet tube B slopes downward and carries a two-way stop-cock, C, and the branch tube D, and at the end is bent down and inserted in a test-tube, E. The branch tube D is about 30 cm. long and is immersed to the depth of not more than one centimeter in mercury that stands in the bottom of the small cylinder F. This arrangement serves to collect in F water that may flow down the side tube D and furnishes also a safety-valve for the release of pressure whenever stoppage occurs in the tube IV. The object of this device is to catch most of the water evolved in the decomposition of the ammonium nitrate, preventing, on the one hand, the passage of the large amount of moisture into the drying agents beyond, and on the other hand, the return flow of the condensed moisture into the flask A. During the operation the two-way stopcock C stands in such a position that the flask communicates with the drying agents beyond. Whenever it is desired to stop the flow of nitrous oxide through the apparatus the stop-cock is turned to such a position as allows the escape of the gas through its lower end. The test-tube E serves to collect the condensed water that may have passed beyond the side arm D. The outlet tube from E is connected with U-tubes L M containing soda-lime, and beyond these are three U-tubes NOP containing fused sodium hydroxide. The gas then enters the inlet tube W of the apparatus R. The generation of the nitrous oxide is now begun and when all air has been displaced from the apparatus the iron can is heated to a temperature of 190° C. In this part of the operation the gas is not bubbled through the molten sodium amide because the product is solid and would cause stoppage of the tube. The conversion of the 25 grams of sodium amide takes about five hours. The end of the reaction is indicated by the absence of ammonia in the gas escaping from the outlet tube of the can. When the conversion is complete, the flame under the can is extinguished and the contents of the nickel dish is allowed to cool in a current of nitrous oxide. The cold product, consisting of a mixture of sodium azide and sodium hydroxide is then dissolved in water. Hydrazoic acid is distilled off in the manner previously described. If the process has been properly conducted, no gas will be evolved when the final product is dissolved in water.

Contributions to the chemistry of hydronitric acid and the inorganic trinitrides, by B. A. Wesley, 23-26, 1904





InChI Key


Canonical SMILES


MeSH Synonyms

Azide, Sodium, NaN3, Sodium Azide

Depositor-Supplied Synonyms

sodium azide, Azide, sodium, 26628-22-8, SMITE, azidosodium, Natriumazid, Sodiumazide, Nemazyd, Kazoe, Sodium azide (Na(N3)), Azoture de sodium, hydrazoic acid, sodium salt, Natriumazid [German], Azydek sodu [Polish], Natriummazide [Dutch], Caswell No. 744A, NSC 3072, RCRA waste no. P105, RCRA waste number P105, Azoture de sodium [French], UNII-968JJ8C9DV, Sodium, azoture de [French], CHEMBL89295, Sodium, azoturo di [Italian], CCRIS 1261, HSDB 695, CHEBI:278547, NCI-C06462, EINECS 247-852-1, UN1687, EPA Pesticide Chemical Code 107701, AI3-50436, DSSTox_CID_121, U-3886, DSSTox_RID_75383, DSSTox_GSID_20121, CAS-26628-22-8, Natriummazide, sodium-azide, Azydek sodu, sodium azid e, Sodium azide, Sodium, azoture de, Sodium, azoturo di, AC1L1PTZ, AC1NAJ6L, AC1Q1UC7, Sodium azide (nominal conc.), 968JJ8C9DV, CTK1A3263, MolPort-003-926-297, PXIPVTKHYLBLMZ-UHFFFAOYSA-N, LTBB004467, Sodium azide [UN1687] [Poison], Tox21_202461, Tox21_300024, ANW-56399, Sodium azide [UN1687] [Poison], AKOS015833396, AKOS015951264, LS-1109, NCGC00090996-01, NCGC00254054-01, NCGC00260010-01, KB-60499, sodium triaza-1,2-dien-2-ium-1,3-diide, TL8002120, TR-012046, S0489, I14-31818, 108592-00-3, 12136-89-9, 157302-08-4, 20828-18-6, 503002-54-8, 575502-02-2

Removed Synonyms

Azium, azide, :sodium azide, NaN3, Hydrazoic acid sodium salt, CID33557, D019810

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