Preparation of Sodium Azide [Archive] - The Explosives and Weapons Forum

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NightStalker

March 4th, 2003, 02:11 AM

Was going through some of my files and ran across a PDF that had some procedures detailed for making various chemicals of interest to the advanced pyro. One of them was sodium azide. The utility of this chemical is obvious.

<blockquote>quote:<hr />
N2H4 + HNO2 = HN3 + 2H2O

A quantity of hydrazine sulfate corresponding to 5 grams of hydrazine hydrate is ground with 37.5ml of 4N sodium methoxide solution, and the sodium sulfate that precipitated is filtered off. The filtered solution is then dissolved in 50 ml. of absolute ethyl ether, cooled with ice, and 12.6 ml. of ethyl nitrite added. The solution is allowed to stand for a while in the ice and is then slowly warmed to room temperature. The NaN3 precipitates and is washed, after suction filtration, with a methanol-ether mixture.

Another procedure is to dissolve 26 g. of hydrazine sulfate in 140 ml. of sodium hydroxide solution (containing 28 g. of NaOH), add 22ml. of ethyl nitrite, and shake the mixture for six hours in a pressure bottle. The unreacted ethyl nitrite is purged with air, and the alcohol is similarly removed on a water bath. The solution is used directly for the preparation of HN3.

Refs:
Helv. Chim. Acta 38, 1834 (1955)
<hr /></blockquote>Now, the question is, how do you make ethyl nitrite? I looked it up in Saxon's chemistry book (Granddad's, page 157, subpage 198) and saw:

<blockquote>quote:<hr />
...is best prepared by directing the nitrous fumes, produced by the action of starch on HNO3 under the influence of heat, into alcohol, contained in a retort connected with a well-cooled receiver.
<hr /></blockquote>I've also seen distilling a mix of acid, nitrite salt, and alcohol as a possible prep. Anyone have a more detailed prep method?

Hydrazine Sulphate prep:

<blockquote>quote:<hr />
2NH3 + NaOCl + H2SO4 = N2H6SO4 + NaCl + H2O
34.1......74.4......98.1......130.1.......58.5...1 8.0

A 1N sodium hypochlorite solution (100 ml.) is added to 200 ml. of 20% ammonia water and 5 ml. of 1% limewater in a one-liter Erlenmeyer flask. The mixture is heated rapidly to boiling and maintained at that temperature for 1/2 hour so that all excess NH3 is removed and the volume of the solution is reduced to about one half.

The solution is then rapidly cooled; sulfuric acid is added to the lukewarm solution until a pH of 7-8 is reached (check with pH paper) and the mixture is left to stand for some time until the gray gelatinous substance settles out. The solution is filtered and the filtrate strongly acidified with sulfuric acid.

After standing overnight the hydrazine sulfate is filtered. It is already quite pure but can be further purified by recrystallization from boiling water.

PROPERTIES:
Shiny, glasslike tablets or prisms. Very slightly soluble in cold water (at 22&degC, 3.05 g./100 ml. H2O); readily soluble in hot water. Insoluble in alcohol. M.p. 254&degC (dec.).
<hr /></blockquote>What percentage would a 1N NaOCl solution be? Would it be 10% pool bleach? 5.25% household, or some fraction of these? What is the saturation percentage of ammonia in water at STP?

[ March 04, 2003, 01:15 AM: Message edited by: NightStalker ]

IPN

March 4th, 2003, 09:51 AM

For a good and clear hydrazine sulphate synthesis look at this topic:
<a href="http://www.roguesci.org/cgi-bin/ewforum/ultimatebb.cgi?ubb=get_topic;f=1;t=000098" target="_blank">http://www.roguesci.org/cgi-bin/ewforum/ultimatebb.cgi?ubb=get_topic;f=1;t=000098</a>

And you can use isopropyl nitrite instead of ethyl nitrite.

Also this might help: (From femfep)

<blockquote>quote:<hr />

Preparation of Hydrazinium sulfate.
2 NH + NaOCl + H SO ---> N H * H SO + NaCl + H O
3 2 4 2 4 2 4 2

One-hundred-forty-one ml of Chlorox bleach (5.25 percent NaOCl) was added to 200 ml of 20 percent ammonium hydroxide and 5 ml of 1 percent limewater Ca(OH)2 in one liter Erlenmeyer flask. The mixture was rapidly heated to boiling and maintained until the volume was reduced to about half, which required about one-half hour. The solution was rapidly cooled and dilute sulfuric acid was added until a pH of 7-8 has attained and the precipitate that formed was separated by filtration. The cold filtrate was strongly acidified with 40 percent sulfuric acid. The white precipitate was filtered, washed with methanol and air dried. Melting point 254 degrees C (lit. 254 degrees C).

Preparation of Isopropyl Nitrite
A mixture of 45 ml concentrated sulfuric acid, 30 ml water and 110 ml isopropyl alcohol, previously cooled to 0 centigrades, was added to an ice cold solution of 114 grams of sodium nitrite in 450 ml of H2O. Slow addition required about two hours in order to maintain a temperature around 0 centigrades. The upper oily layer was separated and washed three times with 30 ml portions of 5 gram 100 ml sodium bicarbonate solution and 22 grams NaCl 100 ml solution respectively.

Preparation of Sodium Azide
N H * H O + NaOH + C H ONO ---> NaN + C H OH + 3H O
2 4 2 4 9 2 3 4 9 2
Five grams of caustic soda (NaOH) was dissolved in 50 ml if ethyl alcohol (3A), and the clear portion was decanted in a 100 ml distilling flask containing 6 ml of hydrazine hydrate. After adding one ml of butyl nitrite (or isopropyl nitrite) the mixture was heated on a steam bath to initiate the reaction. Twelve ml more of the nitrite was slowly added in such a manner that the mixture refluxed slowly. Addition required about one hour and the mixture was heated an additional fifteen minutes. The reaction flask was cooled and the solid product collected on a filter. The product was washed with alcohol and air dried. Recrystallization from water yielded white crystalline material.

<hr /></blockquote>

[ March 04, 2003, 08:53 AM: Message edited by: IPN ]

Alchemist

March 4th, 2003, 10:40 AM

Hello all,

for Hydrazine Sulphate see Rhodium's page for an OTC prep using Urea.

Kriegsminister

March 4th, 2003, 02:49 PM

Just two more ways to prepare sodium azide:

Sodium azide can be prepared by reacting sodium amide (NaNH2) with nitrous oxide (N2O) at 180° C.

NaNH2 + N2O --> NaN3 + H2O

Nitrous oxide can easily be produced by carefully heating ammonium nitrate (NH4NO3 --> NH3 + HNO3 --> N2O + 2 H2O).

Another method is to obtain sodium azide by mixing sodium amide (NaNH2) and sodium nitrate (NaNO3) and melting this mixture at 175° C. Byproducts will be sodium hydroxide (NaOH) and ammonia (NH3), but it should be possible to separate the sodium azide from the byproducts.

NaNO3 + 3 NaNH2 --> NaN3 + 3 NaOH + NH3

Since sodium amide isn't a very pleasant chemical it might be a little hard to find.

[ March 04, 2003, 01:50 PM: Message edited by: Kriegsminister ]

Observer

March 4th, 2003, 04:29 PM

Sodium amide is made by reacting sodium metal and gaseous ammonia.
The sodium amide should be molten in the reaction with the N2O(mp 210 degrees C).
NaNH2 + N2O --> NaN3 + H2O
NaNH2 + H2O --> NH3 + NaOH

Edit: And adition of H2SO4 should convert the NaN3 to HN3(for destillation) or maybe precipating your insoluable metal azide by adding the coresponding metal ion(taking the normal precautions ofcourse).

Merck:

<blockquote>quote:<hr />Title: Sodium Amide . CAS Registry number: [7782-92- Additional name(s): Molecular formula: H 2 NNa Molecular weight: Percent Composition: H 5.17%, N 35.90%, Na Line Formula: NaNH 2 Literature references: Prepd from sodium metal and gaseous ammonia (or liq ammonia with ferric nitrate catalyst): Dennis, Browne, Inorg. Syn. 1, 74 (1939); Greenlee, Henne, ibid. 2, 128 (1946); Schenk in Handbook of Preparative Inorganic Chemistry vol. 1, G. Brauer, Ed. (Academic Press, New York, 2nd ed., 1963) pp 465-468. Alter nate method: Bergstrom, Org. Syn. coll. vol. III, 778 (1955). Properties: Crystals, mp 210degrees . The commercial product may be a white to olive-green solid with sea-shell fracture. Begins to volatilize at 400degrees and dec into its elements between 500 and 600degrees. Heat of formation of solid (18degrees; 1 atm): minus32.26 kcal/mole. Heat of soln (21degrees): minus31.06 kcal/mole. Soly in liq ammonia at 20degrees = about 0.1%. Reacts violently with water forming NaOH and NH 3 . The reaction with alcohol is considerably slower. Should be stored in sealed contain ers which prevent all contact with air during storage: Berg strom, Fernelius, Chem. Rev. 12, 63, 75, 78 (1933). When exposed to the atmosphere, sodium amide rapidly absorbs H 2 O and CO 2 . When only limited absorption takes place, as in poorly sealed containers, products are formed which render the resulting mixture highly explosive. The formation of oxidation products is accompanied by the development of a yellow or brownish color. If such a change is no ticed, the substance should be destroyed at once. This is conveniently accomplished by covering with much benzene, toluene, or kerosene and slowly adding dil ethanol with stirring. Melting Point: 210 Note: Caution: Intensely irritating to skin, eyes, mucous membranes. USE: Dehydrating agent. In the production of indigo and hydrazine. Intermediate in the prepn of sodium cyanide. In ammonolysis reactions, in Claisen condensations, alkylation of nitriles and ketones, synthesis of ethynyl compds, acetyle nic carbinols. Fused NaNH 2 dissolves metallic Mg, Zn, Mo, W, quartz, glass, silicates and other substances. <hr /></blockquote>

[ March 04, 2003, 03:37 PM: Message edited by: Observer ]

NightStalker

March 5th, 2003, 01:53 AM

I've got materials on the processes using molten sodium, but I deliberately avoided them, as the risks and capital costs are much higher than the processes provided.

My main intent was preparation of hydrazoic acid as an FAE fuel (or CW), but it's too dangerous to store the pure form for any length of time because of its highly unstable (and toxic) nature, hence the desire to make it in situ from a stable salt.

Alchemist, do you have a link to that synth? There's quite a few different versions of Rhodiums page floating around.

IPN, I already read that link, and felt there was some more info that could be provided regarding the utilization of that material.

Anthony, did you ever try extracting pure NaH3 from the pellets you got out of that airbag you disassembled? Do you still have the pellets?

Anthony

March 5th, 2003, 07:45 AM

No, I never did get round to tying. I never really set up my lab againafter moving, I'm due to move again soon so I'll probably do it then. I do still have the pellets, I might just try them in synth as-is.

NightStalker

March 6th, 2003, 02:17 AM

Using the pellets as-is may be very hazardous, since you've no idea what other materials are mixed in with the azide, and how they'll react with whatever you're using to make whatever it is you're making.

Mr Cool

March 6th, 2003, 01:54 PM

If you crush the pellets up under warm water (with a bit of NaOH added if you like) while stirring to make it dissolve, the iron oxide and silica will settle out if you leave it over night, the solution of pure sodium azide will remain and can be decanted off through a filter paper for use. The "Boron Potassium Nitrate" that the metal housing says it contains is in the igniter, but wouldn't cause problems even if it was in the pellets. Boron would settle out with the other sediment, potassium nitrate will dissolve but not react when making azides.

IIRC Microtek gave details of his experiments with OTC azides. Look around and you should find them, it was quite recent.