Sodium azide

Sodium azide is an ionic solid. Two crystalline forms are known, rhombohedral and hexagonal.{{Wells1984}} Both adopt layered structures. The azide anion is very similar in each form, being centrosymmetric with N–N distances of 1.18 Å. The {{chem2|Na+}} ion has an octahedral geometry. Each azide is linked to six {{chem2|Na+}} centers, with three Na–N bonds to each terminal nitrogen center.{{cite journal|title = The crystal structures of lithium, sodium and strontium azides|journal = Acta Crystallographica Section B|date = 1968-02-15|pages = 262–269|volume = 24|issue = 2|doi = 10.1107/s0567740868002062|first1 = G. E.|last1 = Pringle|first2 = D. E.|last2 = Noakes|doi-access = | bibcode=1968AcCrB..24..262P }}

The common synthesis method is the "Wislicenus process", which proceeds in two steps in liquid ammonia. In the first step, ammonia is converted to sodium amide by metallic sodium:

:{{chem2|2 Na + 2 NH3 → 2 NaNH2 + H2}}

It is a redox reaction in which metallic sodium gives an electron to a proton of ammonia which is reduced in hydrogen gas. Sodium easily dissolves in liquid ammonia to produce solvated electrons responsible for the blue color of the resulting liquid. The {{chem2|Na+}} and {{chem2|NH2–}} ions are produced by this reaction.

The sodium amide is subsequently combined with nitrous oxide:

:{{chem2|2 NaNH2 + N2O → NaN3 + NaOH + NH3}}

These reactions are the basis of the industrial route, which produced about 250 tons per year in 2004, with production increasing due to the increased use of airbags.{{cite encyclopedia |encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry |publisher = Wiley-VCH |year = 2000 |isbn = 9783527306732 |doi = 10.1002/14356007.a13_193 |first1 = Horst H. |last1 = Jobelius |first2 = Hans-Dieter |last2 = Scharff |chapter = Hydrazoic Acid and Azides}}

Curtius and Thiele developed another production process, where a nitrite ester is converted to sodium azide using hydrazine. This method is suited for laboratory preparation of sodium azide:

:{{chem2|2 NaNO2 + 2 C2H5OH + H2SO4 → 2 C2H5ONO + Na2SO4 + 2 H2O}}

:{{chem2|C2H5ONO + N2H4*H2O + NaOH → NaN3 + C2H5OH + 3 H2O}}

Alternatively the salt can be obtained by the reaction of sodium nitrate with sodium amide.{{Holleman&Wiberg}}.

:{{chem2| 3 NaNH2 + NaNO3 → NaN3 + 3 NaOH + NH3}}

Treatment of sodium azide with strong acids gives gaseous hydrazoic acid (hydrogen azide; HN₃), which is also extremely toxic:

:{{chem2|H+ + N3- → HN3}}

Aqueous solutions contain minute amounts of hydrazoic acid, the formation of which is described by the following equilibrium:

:{{chem2|N3- + H2O ⇌ HN3 + OH-}}, K = 10^−4.6

Sodium azide can be destroyed by treatment with in situ prepared nitrous acid (HNO₂; not HNO₃).{{ cite book | author = Committee on Prudent Practices for Handling, Storage, and Disposal of Chemicals in Laboratories, Board on Chemical Sciences and Technology, Commission on Physical Sciences, Mathematics, and Applications, National Research Council | chapter = Disposal of Waste | title = Prudent Practices in the Laboratory: Handling and Disposal of Chemicals | year = 1995 | page = 165 | publisher = National Academy Press | location = Washington, DC | isbn = 978-0-309-05229-0 | chapter-url = http://books.nap.edu/openbook.php?record_id=4911&page=165}}{{citation | last1=Turnbull | first1=Kenneth | last2=Narsaiah | first2=B. | last3=Yadav | first3=J. S. | last4=Yakaiah | first4=T. | last5=Lingaiah | first5=B. P. V. | title=Encyclopedia of Reagents for Organic Synthesis | chapter=Sodium Azide | publisher=John Wiley & Sons, Ltd | publication-place=Chichester, UK | date=2008-03-14 | doi=10.1002/047084289x.rs045.pub2 | page=| isbn=978-0471936237}} In situ preparation is necessary as HNO₂ is unstable and decomposes rapidly in aqueous solutions. This destruction must be done with great caution and within a chemical fume hood as the formed gaseous nitric oxide (NO) is also toxic, and an incorrect order of acid addition for in situ formation of HNO₂ will instead produce gaseous highly toxic hydrazoic acid (HN₃).

:{{chem2|2 NaN3 + 2 HNO2 → 3 N2 + 2 NO + 2 NaOH}}

Older airbag formulations contained mixtures of oxidizers, sodium azide and other agents including ignitors and accelerants. An electronic controller detonates this mixture during an automobile crash:

:{{chem2|2 NaN3 → 2 Na + 3 N2}}

The same reaction occurs upon heating the salt to approximately 300 °C. The sodium that is formed is a potential hazard alone and, in automobile airbags, it is converted by reaction with other ingredients, such as potassium nitrate and silica. In the latter case, innocuous sodium silicates are generated.{{cite journal | author = Betterton, E. A. | title = Environmental Fate of Sodium Azide Derived from Automobile Airbags | journal = Critical Reviews in Environmental Science and Technology | year = 2003 | volume = 33 | issue = 4 | pages = 423–458 | doi = 10.1080/10643380390245002 | bibcode = 2003CREST..33..423B | s2cid = 96404307 }} While sodium azide is still used in evacuation slides on modern aircraft, newer-generation automotive air bags contain less sensitive explosives such as nitroguanidine or guanidine nitrate.{{cite journal |last1=Halford |first1=Bethany |title=What chemicals make airbags inflate, and how have they changed over time? |journal=Chemical & Engineering News |date=November 15, 2022 |volume=100 |issue=41 |url=https://cen.acs.org/safety/chemicals-make-airbags-inflate-changed/100/i41 |access-date=4 June 2023 |quote=The chemical reaction used to deploy airbags has evolved, but one iteration resulted in massive recalls}} {{open access}}

Due to its explosion hazard, sodium azide is of only limited value in industrial-scale organic synthesis. In the laboratory, it is used to introduce the azide functional group by displacement of halides. The azide functional group can thereafter be converted to an amine by reduction with either Tin(II) chloride in ethanol or lithium aluminium hydride or a tertiary phosphine, such as triphenylphosphine in the Staudinger reaction, with Raney nickel or with hydrogen sulfide in pyridine. Oseltamivir, an antiviral medication, is currently produced in commercial scale by a method which utilizes sodium azide.{{cite journal |author1=Rohloff John C. |author2=Kent Kenneth M. |author3=Postich Michael J. |author4=Becker Mark W. |author5=Chapman Harlan H. |author6=Kelly Daphne E. |author7=Lew Willard |author8=Louie Michael S. |author9=McGee Lawrence R. | year = 1998 | title = Practical Total Synthesis of the Anti-Influenza Drug GS-4104 | journal = J. Org. Chem. | volume = 63 | issue = 13| pages = 4545–4550 | doi = 10.1021/jo980330q |display-authors=etal}}

Sodium azide is a versatile precursor to other inorganic azide compounds, e.g., lead azide and silver azide, which are used in detonators as primary explosives. These azides are significantly more sensitive to premature detonation than sodium azide and thus have limited applications. Lead and silver azide can be made via double displacement reaction with sodium azide and their respective nitrate (most commonly) or acetate salts. Sodium azide can also react with the chloride salts of certain alkaline earth metals in aqueous solution, such as barium chloride or strontium chloride to respectively produce barium azide and strontium azide, which are also relatively sensitive primarily explosive materials. These azides can be recovered from solution through careful desiccation.

Sodium azide is a useful probe reagent, and an antibacterial preservative for biochemical solutions. In the past merthiolate and chlorobutanol were also used as an alternative to azide for preservation of biochemical solutions.{{cite book | last=Scopes | first=Robert K. | title=Protein Purification | publisher=Springer New York | publication-place=New York, NY | year=1994 | isbn=978-1-4419-2833-7 | doi=10.1007/978-1-4757-2333-5 | page=204}}

Sodium azide is an instantaneous inhibitor of lactoperoxidase, which can be useful to stop lactroperoxidase catalyzed ¹²⁵I protein radiolabeling experiments.{{cite book | last=Deutscher | first=M.P. | title=Guide to Protein Purification | publisher=Academic Press | series=Methods in enzymology | year=1990 | isbn=978-0-12-182083-1 | url=https://books.google.com/books?id=zTiRJHpKIQoC&pg=PR11 | access-date=2023-04-10 | page=729}}

In hospitals and laboratories, it is a biocide; it is especially important in bulk reagents and stock solutions which may otherwise support bacterial growth where the sodium azide acts as a bacteriostatic by inhibiting cytochrome oxidase in gram-negative bacteria; however, some gram-positive bacteria (streptococci, pneumococci, lactobacilli) are intrinsically resistant.{{cite journal |author1=Lichstein, H. C. |author2=Soule, M. H. | title = Studies of the Effect of Sodium Azide on Microbic Growth and Respiration: I. The Action of Sodium Azide on Microbic Growth | journal = Journal of Bacteriology | volume = 47 | issue = 3 | pages = 221–230 | year = 1943 |doi=10.1128/JB.47.3.221-230.1944 | pmid = 16560767 | pmc = 373901}}

It is used in agriculture for pest control of soil-borne pathogens such as Meloidogyne incognita or Helicotylenchus dihystera.Applications of sodium azide for control of soilborne pathogens in potatoes. Rodriguez-Kabana, R., Backman, P. A. and King, P.S., Plant Disease Reporter, 1975, Vol. 59, No. 6, pp. 528-532 ([http://www.cabdirect.org/abstracts/19750821668.html link])

It is also used as a mutagen for crop selection of plants such as rice,{{cite journal|title = Mutagenic Effects of Sodium Azide in Rice1|journal = Crop Science|date = 2000-01-01|volume = 20|issue = 5|doi = 10.2135/cropsci1980.0011183x002000050030x|first1 = M. Afsar|last1 = Awan|first2 = C. F.|last2 = Konzak|first3 = J. N.|last3 = Rutger|first4 = R. A.|last4 = Nilan|pages = 663–668}} barley{{cite journal|title = Biological and genetic effects of combined treatments of sodium azide, gamma rays and EMS in barley|journal = Environmental and Experimental Botany|pages = 281–288|volume = 28|issue = 4|doi = 10.1016/0098-8472(88)90051-2|first1 = Xiongying|last1 = Cheng|first2 = Mingwei|last2 = Gao|year = 1988| bibcode=1988EnvEB..28..281C }} or oats.{{cite journal|title = Sodium azide mutagenesis in diploid and hexaploid oats and comparison with ethyl methanesulfonate treatments|journal = Environmental and Experimental Botany|date = 1985-02-01|pages = 7–16|volume = 25|issue = 1|doi = 10.1016/0098-8472(85)90043-7|first = H. W.|last = Rines| bibcode=1985EnvEB..25....7R }}

Sodium azide can be fatally toxic,{{cite journal|title = Human Health Effects of Sodium Azide Exposure: A Literature Review and Analysis|journal = International Journal of Toxicology|date = 2003-05-01|issn = 1091-5818|pmid = 12851150|pages = 175–186|volume = 22|issue = 3|doi = 10.1080/10915810305109|first1 = Soju|last1 = Chang|first2 = Steven H.|last2 = Lamm|s2cid = 38664824}} and even minute amounts can cause symptoms. The toxicity of this compound is comparable to that of soluble alkali cyanides,{{cite web | url = http://hazard.com/msds/mf/baker/baker/files/s2906.htm | title = MSDS: sodium azide | id = MSDS S2906 | publisher = Mallinckrodt Baker | date = 2008-11-21 }} although no toxicity has been reported from spent airbags.{{cite book|first1=Kent |last1=Olson|first2=Ilene B. |last2=Anderson|title=Poisoning & Drug Overdose, 5th Edition|url={{google books |plainurl=y |id=25avFCpfQAcC|page=123}}|date=18 September 2006|publisher=McGraw-Hill Companies, Incorporated|isbn=978-0-07-144333-3|pages=123}}

It produces extrapyramidal symptoms with necrosis of the cerebral cortex, cerebellum, and basal ganglia. Toxicity may also include hypotension,{{cite journal|title = Kidney International - Abstract of article: Epidemic hypotension in a dialysis center caused by sodium azide|journal = Kidney Int|date = 1990-01-01|issn = 0085-2538|pages = 110–115|volume = 37|issue = 1|doi = 10.1038/ki.1990.15|pmid = 2299796|last1 = Gordon|first1 = Steven M.|last2 = Drachman|first2 = Jonathan|last3 = Bland|first3 = Lee A.|last4 = Reid|first4 = Marie H.|last5 = Favero|first5 = Martin|last6 = Jarvis|first6 = William R.|doi-access = free}} blindness and hepatic necrosis. Sodium azide increases cyclic GMP levels in the brain and liver by activation of guanylate cyclase.{{cite journal|title = Increases in cyclic GMP levels in brain and liver with sodium azide an activator of guanylate cyclase|journal = Nature|date = 1975-10-23|pages = 700–702|volume = 257|issue = 5528|doi = 10.1038/257700a0|pmid = 241939|first1 = Hiroshi|last1 = Kimura|first2 = Chandra K.|last2 = Mittal|first3 = Ferid|last3 = Murad|bibcode = 1975Natur.257..700K|s2cid = 115294}}

Sodium azide solutions react with metallic ions to precipitate metal azides, which can be shock sensitive and explosive. This should be considered for choosing a non-metallic transport container for sodium azide solutions in the laboratory. This can also create potentially dangerous situations if azide solutions should be directly disposed down the drain into a sanitary sewer system. Metal in the plumbing system could react, forming highly sensitive metal azide crystals which could accumulate over years. Adequate precautions are necessary for the safe and environmentally responsible disposal of azide solution residues.{{cite web|url=https://www.northeastern.edu/ehs/ehs-programs/hazardous-waste-management/fact-sheets/sodium-azide/|title = Sodium Azide | Environmental Health & Safety | Northeastern University}}

{{anchor|Suicide}}

Sodium azide has gained attention in the Netherlands{{Cite journal |last1=Bruin |first1=Maaike A. C. |last2=Dekker |first2=Douwe |last3=Venekamp |first3=Nikkie |last4=Tibben |first4=Matthijs |last5=Rosing |first5=Hilde |last6=de Lange |first6=Dylan W. |last7=Beijnen |first7=Jos H. |last8=Huitema |first8=Alwin D. R. |date=March 2021 |title=Toxicological analysis of azide and cyanide for azide intoxications using gas chromatography |journal=Basic & Clinical Pharmacology & Toxicology |language=en |volume=128 |issue=3 |pages=534–541 |doi=10.1111/bcpt.13523 |issn=1742-7835 |pmc=7984282 |pmid=33090684}} and abroad[https://yar.aif.ru/archive/1809853 Конец скорпиона] // Аргументы и факты as a chemical used for homicidal and suicidal purposes.

Sodium azide has been attributed to at least 172 deaths in the period from 2015 to 2022 as part of an illicit substance used as a suicide aid commonly called drug X (Dutch: middel X){{Cite web |date=18 April 2024 |title=Zeker 172 mensen overleden door zelfdoding met middel X |trans-title=At least 172 people have died by suicide due to drug X |url=https://www.nu.nl/gezondheid/6309490/zeker-172-mensen-overleden-door-zelfdoding-met-middel-x.html |website=NU.nl |language=nl}} In 2021, a review of all case reports of sodium azide intoxication indicated that 37% of cases were suicide attempts.{{Cite journal |last1=Wachełko |first1=Olga |last2=Zawadzki |first2=Marcin |last3=Szpot |first3=Paweł |date=2021-07-30 |title=A novel procedure for stabilization of azide in biological samples and method for its determination (HS-GC-FID/FID) |journal=Scientific Reports |language=en |volume=11 |issue=1 |page=15568 |doi=10.1038/s41598-021-95104-5 |issn=2045-2322 |pmc=8324859 |pmid=34330976}} An increase in the usage of sodium azide as a suicide drug has been attributed to its availability through pyrotechnics-focused online stores.{{Cite journal |last1=van der Heijden |first1=Lisa T. |last2=van den Hondel |first2=Karen E. |last3=Olyslager |first3=Erik J. H. |last4=de Jong |first4=Lutea A. A. |last5=Reijnders |first5=Udo J. L. |last6=Franssen |first6=Eric J. F. |date=2023-07-13 |title=Internet-Purchased Sodium Azide Used in a Fatal Suicide Attempt: A Case Report and Review of the Literature |journal=Toxics |language=en |volume=11 |issue=7 |pages=608 |doi=10.3390/toxics11070608 |doi-access=free |issn=2305-6304 |pmc=10385699 |pmid=37505573|bibcode=2023Toxic..11..608V }}

The US CDC reports that there is no specific antidote for azide poisoning.{{cite web |title=Sodium Azide |url=https://www.cdc.gov/chemical-emergencies/chemical-fact-sheets/sodium-azide.html |website=Chemical Emergencies (US CDC) |language=en-us |date=6 September 2024}} A 2021 narrative review identifies several cases of survival from ingestion when the patient is treated with antidotes for cyanide poisoning. From a mechanistic standpoint, hydroxocobalamin is more likely to be helpful than other antidotes such as sodium nitrite and sodium thiosulfate. As a result, the recommended treatment is hemodynamic support and hydroxocobalamin. First responders should use personal protection equipment to protect themselves from azide exposure.{{cite journal |last1=Tat |first1=John |last2=Heskett |first2=Karen |last3=Satomi |first3=Shiho |last4=Pilz |first4=Renate B. |last5=Golomb |first5=Beatrice A. |last6=Boss |first6=Gerry R. |title=Sodium azide poisoning: a narrative review |journal=Clinical Toxicology |date=3 August 2021 |volume=59 |issue=8 |pages=683–697 |doi=10.1080/15563650.2021.1906888|pmid=34128439 |pmc=8349855 }}

A 2023 research article reports that hydroxocobalamin reverses azide poisoning in cell cultures, fruit flies, and mice.{{cite journal |last1=Tat |first1=J |last2=Chang |first2=SC |last3=Link |first3=CD |last4=Razo-Lopez |first4=S |last5=Ingerto |first5=MJ |last6=Katebian |first6=B |last7=Chan |first7=A |last8=Kalyanaraman |first8=H |last9=Pilz |first9=RB |last10=Boss |first10=GR |title=The vitamin B(12) analog cobinamide ameliorates azide toxicity in cells, Drosophila melanogaster, and mice. |journal=Clinical Toxicology |date=April 2023 |volume=61 |issue=4 |pages=212–222 |doi=10.1080/15563650.2023.2185125 |pmid=37010385 |pmc=10348668}}

A potential future treatment for both azide and cyanide poisioning is trans-[14]-dienyl cobalt(II) (5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-dienyl cobalt(II), CoN₄[14]), which binds to the two ions with higher affinity than hydroxocobalamin in vitro and has good efficacy in mice.{{cite journal |last1=Pearce |first1=LL |last2=Garrett |first2=KK |last3=Bae |first3=Y |last4=Frawley |first4=KL |last5=Totoni |first5=SC |last6=Peterson |first6=J |title=A Potential Antidote for Both Azide and Cyanide Poisonings. |journal=The Journal of Pharmacology and Experimental Therapeutics |date=17 January 2024 |volume=388 |issue=2 |pages=596–604 |doi=10.1124/jpet.123.001719 |pmid=38182416 |pmc=10801750}}

{{Reflist|2}}

• [http://www.inchem.org/documents/icsc/icsc/eics0950.htm International Chemical Safety Card 0950].
• [https://www.cdc.gov/niosh/npg/npgd0560.html NIOSH Pocket Guide to Chemical Hazards].
• {{cite web | url-status=live | access-date=2022-10-25 | archive-date=2020-07-31 | year=2006 | last=R. | website=The Straight Dope | first=Frances | archive-url=https://web.archive.org/web/20200731095219/https://www.straightdope.com/columns/read/2681/is-there-poison-in-auto-air-bags/ | url=https://www.straightdope.com/columns/read/2681/is-there-poison-in-auto-air-bags/ | title=Is there poison in auto air bags?}}

{{Sodium compounds}}

{{Azides}}

Category:Sodium compounds

Category:Azides

Category:Explosive chemicals