Sodium azide is the
chemical compoundA chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
with the
formulaA chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
NaN
3. This colourless
azideAzide is the anion with the formula N
3−. It is the conjugate base of hydrazoic acid. N
3− is a linear anion that is isoelectronic with CO
2 and N
2O. Per valence bond theory, azide can be described by several resonance structures, an...
salt is a common reagent in
organic synthesisOrganic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...
, and it is a component in many car
airbagAn airbag is a vehicle safety device. It is an occupant restraint consisting of a flexible envelope designed to inflate rapidly in an automobile collision, to prevent vehicle occupants from striking interior objects such as the steering wheel or window....
systems.
Sodium azide is ionic. The N
3- group is centrosymmetric with N–N distances of 1.18 Å. Sodium azide is highly soluble in
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
. Such solutions contain minute amounts of hydrogen azide, as described by the following equilibrium:
- N3- + H2O HN3 + OH- K = 10-4.6
The common synthesis method is the "
WislicenusJohannes Adolf Wislicenus was a German chemist who was born in Klein-Eichstedt in Thuringia. He studied in Zürich and later attained the chair of chemistry at Würzburg and Leipzig...
process," which proceeds in two steps from ammonia.
Sodium azide is the
chemical compoundA chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
with the
formulaA chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
NaN
3. This colourless
azideAzide is the anion with the formula N
3−. It is the conjugate base of hydrazoic acid. N
3− is a linear anion that is isoelectronic with CO
2 and N
2O. Per valence bond theory, azide can be described by several resonance structures, an...
salt is a common reagent in
organic synthesisOrganic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...
, and it is a component in many car
airbagAn airbag is a vehicle safety device. It is an occupant restraint consisting of a flexible envelope designed to inflate rapidly in an automobile collision, to prevent vehicle occupants from striking interior objects such as the steering wheel or window....
systems.
Structure
Sodium azide is ionic. The N
3- group is centrosymmetric with N–N distances of 1.18 Å. Sodium azide is highly soluble in
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
. Such solutions contain minute amounts of hydrogen azide, as described by the following equilibrium:
- N3- + H2O HN3 + OH- K = 10-4.6
Preparation
The common synthesis method is the "
WislicenusJohannes Adolf Wislicenus was a German chemist who was born in Klein-Eichstedt in Thuringia. He studied in Zürich and later attained the chair of chemistry at Würzburg and Leipzig...
process," which proceeds in two steps from ammonia. In the first step, ammonia is converted to
sodium amideSodium amide, commonly called sodamide, is the chemical compound with the formula NaNH
2. This solid, which is dangerously reactive toward water, is white when pure, but commercial samples are typically gray due to the presence of small quantities of metallic iron from the manufacturing...
:
- 2 Na + 2 NH3 → 2 NaNH2 + H2
The sodium amide is subsequently combined with
nitrous oxideNitrous oxide, commonly known as happy gas or laughing gas, is a chemical compound with the chemical formula N
2O. At room temperature, it is a colorless non-flammable gas, with a pleasant, slightly sweet odor and taste. It is used in surgery and dentistry for its anesthetic and analgesic...
:
- 2 NaNH2 + N2O → NaN3 + NaOH + NH3
Alternatively the salt can be obtained by the reaction of
sodium nitrateSodium nitrate is the chemical compound with the formula NaNO
3. This salt, also known as "Chile saltpeter" or "Peru saltpeter" , is a white solid which is very soluble in water...
with sodium amide.
Automobile airbags
Sodium azide cannot be melted, but decomposes vigorously to
sodiumSodium is a metallic element with a symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals within "group 1"...
metal and
nitrogenNitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere.Many industrially important...
gas at approximately 300 °C. The airbag formulations contain mixtures of oxidizers and sodium azide. The formulations are ignited by igniters and accelerants. The igniter is initiated by automobile impact or deceleration:
- 2 NaN3 → 2 Na + 3 N2
The sodium that is formed is a potential hazard itself and, in automobile airbags, it is converted by reaction with other ingredients, such as
potassium nitratePotassium nitrate is a chemical compound with the chemical formula KNO3. A naturally occurring mineral source of nitrogen, KNO3 constitutes a critical oxidizing component of black powder/gunpowder. In the past it was also used for several kinds of burning fuses, including slow...
(KNO
3) and silica (SiO
2), into an inert alkaline silicate 'glass'.
Organic synthesis
Sodium azide is used in organic synthesis to introduce the azide functional group by displacement of a primary
halideA halide is a binary compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. Many salts are halides...
. The azide functional group can thereafter be converted to an
amineAmines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...
by reduction with either
lithium aluminium hydrideLithium aluminium hydride , commonly abbreviated to LAH, is a reducing agent used in organic synthesis. It is more powerful than the related reagent sodium borohydride due to the weaker Al-H bond compared to the B-H bond...
, a tertiary
phosphinePhosphine is the common name for phosphorus trihydride , also known by the IUPAC name phosphane and, occasionally, phosphamine. It is a colorless, flammable gas with a boiling point of −88 °C at standard pressure...
such as
triphenylphosphineTriphenylphosphine is a common organophosphorus compound with the formula P3 - often abbreviated to PPh3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists as relatively air stable, colorless crystals at...
in the
Staudinger reactionThe Staudinger reaction or Staudinger reduction is a chemical reaction in which the combination of an azide with a phosphine or phosphite produces an iminophosphorane intermediate. Combined with the hydrolysis of the aza-ylide to produce a phosphine oxide and an amine, this reaction is a mild...
, or with
Raney nickelRaney nickel is a solid catalyst composed of fine grains of a nickel-aluminium alloy, used in many industrial processes. It was developed in 1926 by American engineer Murray Raney as an alternative catalyst for the hydrogenation of vegetable oils in industrial processes...
.
Biochemistry and biomedical uses
Sodium azide is a useful probe reagent,
mutagenIn biology, a mutagen is a physical or chemical agent that changes the genetic material of an organism and thus increases the frequency of mutations above the natural background level. As many mutations cause cancer, mutagens are typically also carcinogens...
, and
preservativeA preservative is a natural or synthetic chemical that is added to products such as foods, pharmaceuticals, paints, biological samples, wood, etc. to prevent decomposition by microbial growth or by undesirable chemical changes.-Preservatives in wood:...
. In hospitals and laboratories, it is a
biocideA biocide is a chemical substance capable of killing living organisms, usually in a selective way. Biocides are commonly used in medicine, agriculture, forestry, and in industry where they prevent the fouling of water and oil pipelines...
; it is especially important in bulk reagents and
stock solutionIn chemistry, a stock solution is a large volume of a common reagent, such as hydrochloric acid or sodium hydroxide, at a standardized concentration. This term is commonly used in analytical chemistry for procedures such as titrations, where it is important that exact concentrations of solutions...
s which may otherwise support
bacteriaThe bacteria are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
l growth where the sodium azide acts as a bacteriostatic by inhibiting cytochrome oxidase in
gram-negativeGram-negative bacteria are those bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...
bacteria;
gram-positiveGram-positive bacteria are those that are stained dark blue or violet by Gram staining. This is in contrast to Gram-negative bacteria, which cannot retain the crystal violet stain, instead taking up the counterstain and appearing red or pink...
(streptococci,
pneumococciStreptococcus pneumoniae, or pneumococcus, is Gram-positive, alpha-hemolytic, bile soluble aerotolerant anaerobe and a member of the genus Streptococcus. A significant human pathogenic bacterium, S...
,
lactobacilliBacillus is a genus of rod-shaped bacteria and a member of the division Firmicutes. Bacillus species are obligate aerobes, and test positive for the enzyme catalase. Ubiquitous in nature, Bacillus includes both free-living and pathogenic species. Under stressful environmental conditions, the cells...
) are resistant. (a characteristic similar to
antibiotic resistanceAntibiotic resistance is the ability of a microorganism to withstand the effects of antibiotics. It is a specific type of drug resistance. Antibiotic resistance evolves via natural selection acting upon random mutation, but it can also be engineered by applying an evolutionary stress on a population...
) It is also used in agriculture (farming) for pest control.
Azide inhibits cytochrome oxidase by binding irreversibly to the
hemeA heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin...
cofactorCofactor may refer to any of the following:* Cofactor , the signed minor of a matrix* Minor , an alternative name for the determinant of a smaller matrix than that which it describes...
in a process similar to the action of
carbon monoxideCarbon monoxide is a colorless, odorless and tasteless gas, yet very toxic to humans. It consists of one carbon atom and one oxygen atom, connected by a covalent double bond and a dative covalent bond...
. Sodium azide particularly affects organs that undergo high rates of respiration, such as the
heartThe heart is a muscular organ found in all vertebrates that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
and the
brainThe brain is the center of the nervous system in all vertebrate, and most invertebrate, animals. Some primitive animals such as jellyfish and starfish have a decentralized nervous system without a brain, while sponges lack any nervous system at all...
.
Reactions
Treatment of sodium azide with strong acids gives the corresponding acid,
hydrazoic acidHydrazoic acid, also known as hydrogen azide or azoimide, is a colorless, volatile, and extremely explosive liquid at room temperature and pressure. It is a compound of nitrogen and hydrogen, having chemical formula HN3. It was first isolated in 1890 by Theodor Curtius...
:
- H2SO4 + NaN3 → HN3 + NaHSO4
Sodium azide can be destroyed by treatment with
nitrous acidNitrous acid is a weak and monobasic acid known only in solution and in the form of nitrite salts.Nitrous acid is used to make diazides from amines; this occurs by nucleophilic attack of the amine onto the nitrite, reprotonation by the surrounding solvent, and double-elimination of water...
solution:
- 2 NaN3 + 2 HNO2 → 3 N2 + 2 NO + 2 NaOH
Safety
Sodium azide is often compared with
cyanideA cyanide is any chemical compound that contains the cyano group , which consists of a carbon atom triple-bonded to a nitrogen atom. Inorganic cyanides are hydrogen cyanide salts in which cyanide is generally the anion CN
-. Organic compounds that have a -C≡N functional group bonded to...
, as poisoned individuals suffer from the same symptoms. Exposure to sodium azide has some or all of the following symptoms within minutes: rapid breathing, restlessness, dizziness, weakness, headache, nausea and vomiting, rapid heart rate, red eyes (gas or dust exposure), clear drainage from the nose (gas or dust exposure), cough (gas or dust exposure), skin burns and blisters (explosion or direct skin contact). Exposure to a large amount of sodium azide may cause these other health effects as well:
convulsionA convulsion is a medical condition where body muscles contract and relax rapidly and repeatedly, resulting in an uncontrolled shaking of the body. Because a convulsion is often a symptom of an epileptical seizure, the term convulsion is sometimes used as a synonym for seizure...
s, low
blood pressureBlood pressure is the pressure exerted by circulating blood on the walls of blood vessels, and is one of the principal vital signs. During each heartbeat, BP varies between a maximum and a minimum pressure...
, low
heart rateHeart rate is determined by the number of heartbeats per unit of time, typically expressed as beats per minute , it can vary with as the body's need for oxygen changes, such as during exercise or sleep. The measurement of heart rate is used by medical professionals to assist in the diagnosis and...
, loss of consciousness, and
lungThe lung or pulmonary system is the essential respiration organ in air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located in the chest on either side of the heart...
injury,
respiratory failureThe term respiratory failure, in medicine, is used to describe inadequate gas exchange by the respiratory system, with the result that arterial oxygen and/or carbon dioxide levels cannot be maintained within their normal ranges. A drop in blood oxygenation is known as hypoxemia; a rise in arterial...
leading to death.
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