Hydrazoic acid

Last updated
Hydrazoic acid
Hydrogen-azide-2D-dimensions.png
Hydrazoic acid.svg
Hydrogen-azide-3D-vdW.png
Names
IUPAC name
Hydrogen azide
Other names
Hydrogen azide
Azoimide
Azic acid
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.029.059 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 231-965-8
773
PubChem CID
UNII
  • InChI=1S/HN3/c1-3-2/h1H Yes check.svgY
    Key: JUINSXZKUKVTMD-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/HN3/c1-3-2/h1H
    Key: JUINSXZKUKVTMD-UHFFFAOYAO
  • [N-]=[N+]=N
  • N#[N+][N-H]
Properties
HN3
Molar mass 43.029 g·mol−1
Appearancecolorless, highly volatile liquid
Density 1.09 g/cm3
Melting point −80 °C (−112 °F; 193 K)
Boiling point 37 °C (99 °F; 310 K)
highly soluble
Solubility soluble in alkali, alcohol, ether
Acidity (pKa)4.6 [1]
Conjugate base Azide
Structure
approximately linear
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Highly toxic, explosive, reactive
GHS labelling:
GHS-pictogram-explos.svg GHS-pictogram-exclam.svg GHS-pictogram-silhouette.svg
Danger
H200, H319, H335, H370
P201, P202, P260, P261, P264, P270, P271, P280, P281, P304+P340, P305+P351+P338, P307+P311, P312, P321, P337+P313, P372, P373, P380, P401, P403+P233, P405, P501
NFPA 704 (fire diamond)
NFPA 704.svgHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 0: Will not burn. E.g. waterInstability 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
0
3
Related compounds
Other cations
Sodium azide
Lithium azide
Potassium azide
Ammonia
Hydrazine
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

Hydrazoic acid, also known as hydrogen azide, azic acid or azoimide, [2] is a compound with the chemical formula HN3. [3] It is a colorless, volatile, and explosive liquid at room temperature and pressure. It is a compound of nitrogen and hydrogen, and is therefore a pnictogen hydride. The oxidation state of the nitrogen atoms in hydrazoic acid is fractional and is -1/3.[ citation needed ] It was first isolated in 1890 by Theodor Curtius. [4] The acid has few applications, but its conjugate base, the azide ion, is useful in specialized processes.

Contents

Hydrazoic acid, like its fellow mineral acids, is soluble in water. Undiluted hydrazoic acid is dangerously explosive [5] with a standard enthalpy of formation ΔfHo (l, 298K) = +264 kJ/mol. [6] When dilute, the gas and aqueous solutions (<10%) can be safely prepared but should be used immediately; because of its low boiling point, hydrazoic acid is enriched upon evaporation and condensation such that dilute solutions incapable of explosion can form droplets in the headspace of the container or reactor that are capable of explosion. [7] [8]

Production

The acid is usually formed by acidification of an azide salt like sodium azide. Normally solutions of sodium azide in water contain trace quantities of hydrazoic acid in equilibrium with the azide salt, but introduction of a stronger acid can convert the primary species in solution to hydrazoic acid. The pure acid may be subsequently obtained by fractional distillation as an extremely explosive colorless liquid with an unpleasant smell. [2]

NaN3 + HCl → HN3 + NaCl

Its aqueous solution can also be prepared by treatment of barium azide solution with dilute sulfuric acid, filtering the insoluble barium sulfate. [9]

It was originally prepared by the reaction of aqueous hydrazine with nitrous acid:

N2H4 + HNO2 → HN3 + 2 H2O

With the hydrazinium cation [N2H5]+ this reaction is written as:

[N2H5]+ + HNO2 → HN3 + H2O + [H3O]+

Other oxidizing agents, such as hydrogen peroxide, nitrosyl chloride, trichloramine or nitric acid, can also be used to produce hydrazoic acid from hydrazine. [10]

Destruction prior to disposal

Hydrazoic acid reacts with nitrous acid:

HN3 + HNO2 → N2O + N2 + H2O

This reaction is unusual in that it involves compounds with nitrogen in four different oxidation states. [11]

Reactions

In its properties hydrazoic acid shows some analogy to the halogen acids, since it forms poorly soluble (in water) lead, silver and mercury(I) salts. The metallic salts all crystallize in the anhydrous form and decompose on heating, leaving a residue of the pure metal. [2] It is a weak acid (pKa = 4.75. [6] ) Its heavy metal salts are explosive and readily interact with the alkyl iodides. Azides of heavier alkali metals (excluding lithium) or alkaline earth metals are not explosive, but decompose in a more controlled way upon heating, releasing spectroscopically-pure N2 gas. [12] Solutions of hydrazoic acid dissolve many metals (e.g. zinc, iron) with liberation of hydrogen and formation of salts, which are called azides (formerly also called azoimides or hydrazoates).

Hydrazoic acid may react with carbonyl derivatives, including aldehydes, ketones, and carboxylic acids, to give an amine or amide, with expulsion of nitrogen. This is called Schmidt reaction or Schmidt rearrangement.

Schmidt Reaktion Ubersicht Carbonsauren1.svg
Schmidt Reaktion Ubersicht Ketone1.svg

Dissolution in the strongest acids produces explosive salts containing the aminodiazonium ion [H2N=N=N]+ ⇌ [H2N−N≡N]+, for example: [12]

HN=N=N + H[SbCl6] → [H2N=N=N]+[SbCl6]−

The ion [H2N=N=N]+ is isoelectronic to diazomethane H2C=N+=N−.

The decomposition of hydrazoic acid, triggered by shock, friction, spark, etc. produces nitrogen and hydrogen:

2 HN3 → H2 + 3 N2

Hydrazoic acid undergoes unimolecular decomposition at sufficient energy:

HN3 → NH + N2

The lowest energy pathway produces NH in the triplet state, making it a spin-forbidden reaction. This is one of the few reactions whose rate has been determined for specific amounts of vibrational energy in the ground electronic state, by laser photodissociation studies. [13] In addition, these unimolecular rates have been analyzed theoretically, and the experimental and calculated rates are in reasonable agreement. [14]

Toxicity

Hydrazoic acid is volatile and highly toxic. It has a pungent smell and its vapor can cause violent headaches. The compound acts as a non-cumulative poison.

Applications

2-Furonitrile, a pharmaceutical intermediate and potential artificial sweetening agent has been prepared in good yield by treating furfural with a mixture of hydrazoic acid (HN3) and perchloric acid (HClO4) in the presence of magnesium perchlorate in the benzene solution at 35 °C. [15] [16]

The all gas-phase iodine laser (AGIL) mixes gaseous hydrazoic acid with chlorine to produce excited nitrogen chloride, which is then used to cause iodine to lase; this avoids the liquid chemistry requirements of COIL lasers.

Related Research Articles

<span class="mw-page-title-main">Nitrogen</span> Chemical element, symbol N and atomic number 7

Nitrogen is a chemical element; it has symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seventh in total abundance in the Milky Way and the Solar System. At standard temperature and pressure, two atoms of the element bond to form N2, a colorless and odorless diatomic gas. N2 forms about 78% of Earth's atmosphere, making it the most abundant uncombined element in air. Because of the volatility of nitrogen compounds, nitrogen is relatively rare in the solid parts of the Earth.

<span class="mw-page-title-main">Hydrazine</span> Colorless flammable liquid with an ammonia-like odor

Hydrazine is an inorganic compound with the chemical formula N2H4. It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine hydrate.

In chemistry, azide is a linear, polyatomic anion with the formula N−3 and structure −N=N+=N−. It is the conjugate base of hydrazoic acid HN3. Organic azides are organic compounds with the formula RN3, containing the azide functional group. The dominant application of azides is as a propellant in air bags.

<span class="mw-page-title-main">Hydroxylamine</span> Inorganic compound

Hydroxylamine is an inorganic compound with the formula NH2OH. The material is a white crystalline, hygroscopic compound. Hydroxylamine is almost always provided and used as an aqueous solution. It is consumed almost exclusively to produce Nylon-6. The oxidation of NH3 to hydroxylamine is a step in biological nitrification.

<span class="mw-page-title-main">Nitrous acid</span> Chemical compound

Nitrous acid is a weak and monoprotic acid known only in solution, in the gas phase and in the form of nitrite salts. It was discovered by Carl Wilhelm Scheele, who called it "phlogisticated acid of niter". Nitrous acid is used to make diazonium salts from amines. The resulting diazonium salts are reagents in azo coupling reactions to give azo dyes.

<span class="mw-page-title-main">Sodium azide</span> Chemical compound

Sodium azide is an inorganic compound with the formula NaN3. This colorless salt is the gas-forming component in some car airbag systems. It is used for the preparation of other azide compounds. It is an ionic substance, is highly soluble in water, and is very acutely poisonous.

<span class="mw-page-title-main">Sulfamic acid</span> Chemical compound

Sulfamic acid, also known as amidosulfonic acid, amidosulfuric acid, aminosulfonic acid, sulphamic acid and sulfamidic acid, is a molecular compound with the formula H3NSO3. This colourless, water-soluble compound finds many applications. Sulfamic acid melts at 205 °C before decomposing at higher temperatures to water, sulfur trioxide, sulfur dioxide and nitrogen.

<span class="mw-page-title-main">Chloroplatinic acid</span> Chemical compound

Chloroplatinic acid (also known as hexachloroplatinic acid) is an inorganic compound with the formula [H3O]2[PtCl6](H2O)x (0 ≤ x ≤ 6). A red solid, it is an important commercial source of platinum, usually as an aqueous solution. Although often written in shorthand as H2PtCl6, it is the hydronium (H3O+) salt of the hexachloroplatinate anion (PtCl2−
6). Hexachloroplatinic acid is highly hygroscopic.

<span class="mw-page-title-main">Silver azide</span> Chemical compound

Silver azide is the chemical compound with the formula AgN3. It is a silver(I) salt of hydrazoic acid. It forms a colorless crystals. Like most azides, it is a primary explosive.

The chemical element nitrogen is one of the most abundant elements in the universe and can form many compounds. It can take several oxidation states; but the most common oxidation states are -3 and +3. Nitrogen can form nitride and nitrate ions. It also forms a part of nitric acid and nitrate salts. Nitrogen compounds also have an important role in organic chemistry, as nitrogen is part of proteins, amino acids and adenosine triphosphate.

Diimide, also called diazene or diimine, is a compound having the formula HN=NH. It exists as two geometric isomers, E (trans) and Z (cis). The term diazene is more common for organic derivatives of diimide. Thus, azobenzene is an example of an organic diazene.

<span class="mw-page-title-main">Imidazole-1-sulfonyl azide</span> Chemical compound

Imidazole-1-sulfonyl azide is an organic azide compound that can be used as an alternative organic synthesis reagent to trifluoromethanesulfonyl azide. It is an explosive colorless liquid, but some of its organic-soluble salts can be safely handled and stored as a solid.

<span class="mw-page-title-main">Pentazenium</span> Polytomic cation (N–N–N–N–N)

In chemistry, the pentazenium cation is a positively-charged polyatomic ion with the chemical formula N+5 and structure N−N−N−N−N. Together with solid nitrogen polymers and the azide anion, it is one of only three poly-nitrogen species obtained in bulk quantities.

Barium azide is an inorganic azide with the formula Ba(N3)2. It is a barium salt of hydrazoic acid. Like most azides, it is explosive. It is less sensitive to mechanical shock than lead azide.

Pnictogen hydrides or hydrogen pnictides are binary compounds of hydrogen with pnictogen atoms covalently bonded to hydrogen.

<span class="mw-page-title-main">Rubidium azide</span> Chemical compound

Rubidium azide is an inorganic compound with the formula RbN3. It is the rubidium salt of the hydrazoic acid HN3. Like most azides, it is explosive.

Hydrazinium azide or hydrazine azide is a chemical compound with formula H
5N
5 or [N
2H+
5][N−
3]. It is a salt of the hydrazinium cation N
2H+
5 and the azide anion N−
3. It can be seen as a derivative of hydrazine N
2H
4 and hydrazoic acid HN
3. It is an unstable solid.

<span class="mw-page-title-main">Zinc azide</span> Chemical compound

Zinc azideZn(N3)2 is an inorganic compound composed of zinc cations (Zn2+) and azide anions (N−3). It is a white, explosive solid that can be prepared by the protonolysis of diethylzinc with hydrazoic acid:

<span class="mw-page-title-main">Boron triazide</span> Chemical compound

Boron triazide, also known as triazidoborane, is a thermally unstable compound of boron and nitrogen with a nitrogen content of 92.1 %. Formally, it is the triazido derivative of borane and is a covalent inorganic azide. The high-energy compound, which has the propensity to undergo spontaneous explosive decomposition, was first described in 1954 by Egon Wiberg and Horst Michaud of the University of Munich.

Homoleptic azido compounds are chemical compounds in which the only anion or ligand is the azide group, -N3. The breadth of homoleptic azide compounds spans nearly the entire periodic table. With rare exceptions azido compounds are highly shock sensitive and need to be handled with the upmost caution. Binary azide compounds can take on several different structures including discrete compounds, or one- two, and three-dimensional nets, leading some to dub them as "polyazides". Reactivity studies of azide compounds are relatively limited due to how sensitive they can be. The sensitivity of these compounds tends to be correlated with the amount of ionic or covalent character the azide-element bond has, with ionic character being far more stable than covalent character. Therefore, compounds such as silver or sodium azide – which have strong ionic character – tend to possess more synthetic utility than their covalent counterparts. A few other notable exceptions include polymeric networks which possess unique magnetic properties, group 13 azides which unlike most other azides decompose to nitride compounds (important materials for semiconductors), other limited uses as synthetic reagents for the transfer for azide groups, or interest in high energy density materials.

References

  1. ↑ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN   0-07-049439-8
  2. 1 2 3 Chisholm, Hugh, ed. (1911). "Azoimide"  . Encyclopædia Britannica . Vol. 3 (11th ed.). Cambridge University Press. pp. 82–83. This also contains a detailed description of the contemporaneous production process.
  3. ↑ Dictionary of Inorganic and Organometallic Compounds. Chapman & Hall.
  4. ↑ Curtius, Theodor (1890). "Ueber Stickstoffwasserstoffsäure (Azoimid) N3H" [On hydrazoic acid (azoimide) N3H]. Berichte der Deutschen Chemischen Gesellschaft. 23 (2): 3023–3033. doi:10.1002/cber.189002302232.
  5. ↑ Furman, David; Dubnikova, Faina; van Duin, Adri C. T.; Zeiri, Yehuda; Kosloff, Ronnie (2016-03-10). "Reactive Force Field for Liquid Hydrazoic Acid with Applications to Detonation Chemistry". The Journal of Physical Chemistry C. 120 (9): 4744–4752. Bibcode:2016APS..MARH20013F. doi:10.1021/acs.jpcc.5b10812. ISSN   1932-7447. S2CID   102029987.
  6. 1 2 Catherine E. Housecroft; Alan G. Sharpe (2008). "Chapter 15: The group 15 elements". Inorganic Chemistry, 3rd Edition. Pearson. p. 449. ISBN   978-0-13-175553-6.
  7. ↑ Gonzalez-Bobes, F. et al Org. Process Res. Dev. 2012, 16, 2051-2057.
  8. ↑ Treitler, D. S. et al Org. Process Res. Dev. 2017, 21, 460-467.
  9. ↑ L . F. Audrieth, C. F. Gibbs Hydrogen Azide in Aqueous and Ethereal Solution" Inorganic Syntheses 1939, vol. 1, pp. 71-79.
  10. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 432. ISBN   978-0-08-037941-8.
  11. ↑ Greenwood, pp. 461–464.
  12. 1 2 Egon Wiberg; Nils Wiberg; Arnold Frederick Holleman (2001). "The Nitrogen Group". Inorganic chemistry. Academic Press. p. 625. ISBN   978-0-12-352651-9.
  13. ↑ Foy, B.R.; Casassa, M.P.; Stephenson, J.C.; King, D.S. (1990). "Overtone-excited HN
    3     (X1A') - Anharmonic resonance, homogeneous linewidths, and dissociation rates". Journal of Chemical Physics. 92: 2782–2789. doi:10.1063/1.457924.
  14. ↑ Besora, M.; Harvey, J.N. (2008). "Understanding the rate of spin-forbidden thermolysis of HN
    3     and CH
    3    N
    3    ". Journal of Chemical Physics. 129 (4): 044303. doi:10.1063/1.2953697. PMID   18681642.
  15. ↑ P. A. Pavlov; Kul'nevich, V. G. (1986). "Synthesis of 5-substituted furannitriles and their reaction with hydrazine". Khimiya Geterotsiklicheskikh Soedinenii. 2: 181–186.
  16. ↑ B. Bandgar; Makone, S. (2006). "Organic reactions in water. Transformation of aldehydes to nitriles using NBS under mild conditions". Synthetic Communications. 36 (10): 1347–1352. doi:10.1080/00397910500522009. S2CID   98593006.
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