Sodium azide

Source: Wikipedia, the free encyclopedia.
"NaN3" redirects here. Not to be confused with NaN.
Not to be confused with sodium nitride.
Sodium azide
Names
IUPAC name
Sodium azide
Other names
Sodium trinitride
Smite
Azium
Identifiers
3D model (
JSmol
)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard
 100.043.487 Edit this at Wikidata
EC Number
  • 247-852-1
RTECS number
  • VY8050000
UNII
UN number
1687
  • InChI=1S/N3.Na/c1-3-2;/q-1;+1 checkY
    Key: PXIPVTKHYLBLMZ-UHFFFAOYSA-N checkY
  • InChI=1/N3.Na/c1-3-2;/q-1;+1
    Key: PXIPVTKHYLBLMZ-UHFFFAOYAH
  • [N-]=[N+]=[N-].[Na+]
Properties
NaN3
Molar mass 65.0099 g/mol
Appearance Colorless to white solid
Odor Odorless
Density 1.846 g/cm3 (20 °C)
Melting point 275 °C (527 °F; 548 K) violent decomposition
38.9 g/100 mL (0 °C)
40.8 g/100 mL (20 °C)
55.3 g/100 mL (100 °C)
Solubility Very soluble in ammonia
Slightly soluble in benzene
Insoluble in diethyl ether, acetone, hexane, chloroform
Solubility in methanol 2.48 g/100 mL (25 °C)
Solubility in ethanol 0.22 g/100 mL (0 °C)
Acidity (pKa) 4.8
Structure
Hexagonal, hR12[1]
R-3m, No. 166
Thermochemistry
76.6 J/mol·K
70.5 J/mol·K
Std enthalpy of
formation
(ΔfH⦵298)
 21.3 kJ/mol
99.4 kJ/mol
Hazards
GHS labelling:
GHS01: Explosive GHS06: Toxic GHS08: Health hazard GHS09: Environmental hazard
Danger
H300, H310, H410
P260, P280, P301+P310, P501 [2]
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxideSpecial hazards (white): no code
4
1
3
Flash point 300 °C (572 °F; 573 K)
Lethal dose or concentration (LD, LC):
27 mg/kg (oral, rats/mice)[1]
NIOSH (US health exposure limits):
PEL (Permissible)
 None[3]
REL (Recommended)
 C 0.1 ppm (as HN3) [skin]
C 0.3 mg/m3 (as NaN3) [skin][3]
IDLH
(Immediate danger)
 N.D.[3]
Safety data sheet (SDS) ICSC 0950
Related compounds
Other anions
 Sodium cyanide
Other cations
 Potassium azide
Ammonium azide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Sodium azide is an

ionic substance, is highly soluble in water, and is acutely poisonous.[5]

Structure

Sodium

centrosymmetric with N–N distances of 1.18 Å. The Na+ ion has an octahedral geometry. Each azide is linked to six Na+ centers, with three Na–N bonds to each terminal nitrogen center.[7]

Preparation

The common synthesis method is the "

liquid ammonia. In the first step, ammonia is converted to sodium amide by metallic sodium
:

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 Na+ and NH−2 ions are produced by this reaction.

The sodium amide is subsequently combined with nitrous oxide:

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.[5]

Laboratory methods

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:

2 NaNO2 + 2 C2H5OH + H2SO4 → 2 C2H5ONO + Na2SO4 + 2 H2O
C2H5ONO + N2H4·H2O + NaOH → NaN3 + C2H5OH + 3 H2O

Alternatively the salt can be obtained by the reaction of sodium nitrate with sodium amide.[8]

Chemical reactions

Acid formation of hydrazoic acid

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

H+ + N−3 → HN3

Hydrazoic acid equilibrium

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

N−3 + H2O ⇌ HN3 + OH−, K = 10−4.6

Destruction

Sodium azide can be destroyed by treatment with

HNO3).[9][10] 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).[9]

2 NaN3 + 2 HNO2 → 3 N2 + 2 NO + 2 NaOH

Applications

Automobile airbags and aircraft evacuation slides

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:

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

silica. In the latter case, innocuous sodium silicates are generated.[11] 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.[12]

Organic and inorganic synthesis

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.[10] The azide functional group can thereafter be converted to an amine by reduction with either SnCl2 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.[13]

Sodium azide is a versatile precursor to other inorganic azide compounds, e.g.,

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.

Biochemistry and biomedical uses

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.[14]

Sodium azide is an instantaneous inhibitor of

radiolabeling experiments.[15]

In hospitals and laboratories, it is a

streptococci, pneumococci, lactobacilli) are intrinsically resistant.[16]

Agricultural uses

It is used in agriculture for pest control of soil-borne pathogens such as Meloidogyne incognita or Helicotylenchus dihystera.[17]

It is also used as a mutagen for crop selection of plants such as rice,[18] barley[19] or oats.[20]

Safety considerations

Sodium azide can be fatally toxic,[21] and even minute amounts can cause symptoms. The toxicity of this compound is comparable to that of soluble alkali cyanides,[22] although no toxicity has been reported from spent airbags.[23]

It produces

cyclic GMP levels in the brain and liver by activation of guanylate cyclase.[25]

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.[26]

Intentional consumption

Sodium azide has gained attention in the Netherlands[27] and abroad[28] 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 a illicit substance used as a suicide aid commonly called drug X (Dutch: middel X)[29] In 2021, a review of all case reports of sodium azide intoxication indicated that 37% of cases were suicide attempts.[30] An increase in the usage of sodium azide as a suicide drug has been attributed to its availability through online retailers.[31]

References

  1. ^
    doi:10.1107/S0567739477001855
    .
  2. ^ "Sodium azide".
  3. ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0560". National Institute for Occupational Safety and Health (NIOSH).
  4. ^ "Material Safety Data Sheet" (PDF). Sciencelab.com. November 6, 2008. Archived from the original (PDF) on March 4, 2016. Retrieved October 26, 2015.
  5. ^
    ISBN 9783527306732
    .
  6. ISBN 0-19-855370-6
  7. doi:10.1107/s0567740868002062
    .
  8. ISBN 0-12-352651-5
    .
  9. ^
    ISBN 978-0-309-05229-0.{{cite book}}: CS1 maint: multiple names: authors list (link
    )
  10. ^
    ISBN 978-0471936237
  11. S2CID 96404307
    .
  12. ^ Halford, Bethany (November 15, 2022). "What chemicals make airbags inflate, and how have they changed over time?". Chemical & Engineering News. 100 (41). Retrieved 4 June 2023. The chemical reaction used to deploy airbags has evolved, but one iteration resulted in massive recalls Open access icon
  13. doi:10.1021/jo980330q
    .
  14. ISBN 978-1-4419-2833-7
    .
  15. ISBN 978-0-12-182083-1
    . Retrieved 2023-04-10.
  16. PMID 16560767
    .
  17. ^ 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 (link)
  18. doi:10.2135/cropsci1980.0011183x002000050030x
    .
  19. doi:10.1016/0098-8472(88)90051-2
    .
  20. doi:10.1016/0098-8472(85)90043-7
    .
  21. S2CID 38664824
    .
  22. ^ "MSDS: sodium azide". Mallinckrodt Baker. 2008-11-21. MSDS S2906.
  23. ISBN 978-0-07-144333-3
    .
  24. PMID 2299796
    .
  25. S2CID 115294
    .
  26. ^ "Sodium Azide | Environmental Health & Safety | Northeastern University".
  27. PMID 33090684
    .
  28. ^ Конец скорпиона // Аргументы и факты
  29. ^ "Zeker 172 mensen overleden door zelfdoding met middel X" [At least 172 people have died by suicide due to drug X]. NU.nl (in Dutch). 18 April 2024.
  30. PMID 34330976
    .
  31. PMID 37505573
    .

External links
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