Tetrazole

Tetrazole

IUPAC name 1H-Tetrazole
Identifiers
CAS number	288-94-8^Y
PubChem	67519
ChemSpider	60842^Y
ChEBI	CHEBI:33193
Jmol-3D images	Image 1
SMILES n1nnnc1
InChI InChI=1S/CH2N4/c1-2-4-5-3-1/h1H,(H,2,3,4,5)^Y Key: KJUGUADJHNHALS-UHFFFAOYSA-N InChI=1/CH2N4/c1-2-4-5-3-1/h1H,(H,2,3,4,5) Key: KJUGUADJHNHALS-UHFFFAOYAI InChI=1S/CH2N4/c1-2-4-5-3-1/h1H,(H,2,3,4,5) Key: KJUGUADJHNHALS-UHFFFAOYSA-N
Properties
Molecular formula	CH₂N₄
Molar mass	70.05 g/mol
Density	1.477 g/mL
Melting point	157-158 °C ^[1]
Boiling point	220±23 °C
Acidity (pK_a)	4.90 ^[2]
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Tetrazoles are a class of synthetic organic heterocyclic compound, consisting of a 5-member ring of four nitrogen and one carbon atom (plus hydrogens). The simplest is tetrazole itself, CN₄H₂. They are unknown in nature. There are several pharmaceutical agents which are tetrazoles, but they are generally undesirable due to safety concerns for process-scale synthesis; tetrazoles are usually explosive. However, tetrazoles can act as a bioisostere for the carboxylate group, increasing their utility. Angiotensin II receptor blockers, in particular, often contain tetrazoles, such as losartan and candesartan. A well-known tetrazole is MTT, which is a dimethyl thiazolyl diphenyl tetrazolium salt. This tetrazole is used in the MTT assay to quantify the respiratory activity of live cells in cell culture, although it generally kills the cells in the process.

Other tetrazoles are used for their explosive or combustive properties, such as tetrazole itself and 5-aminotetrazole, which are sometimes used as a component of gas generators in automobile airbags. They produce high-temperature, non-toxic reaction products, and have a high burn rate and (relative) stability, all of which are desirable properties.

Tetrazole was first prepared by the reaction of anhydrous hydrazoic acid and hydrogen cyanide under pressure.

Related heterocycles

Triazoles, analogs with three nitrogen atoms
Pentazole, the analog with five nitrogen atoms (strictly speaking, an inorganic homocycle, not a heterocycle)

References

^ Mihina, Joseph S.; Herbst, Robert M. (1950). "The Reaction of Nitriles with Hydrazoic Acid: Synthesis of Monosubstituted Tetrazoles". J. Org. Chem. 15 (5): 1082–1092. doi:10.1021/jo01151a027.
^ Satchell, Jacqueline F.; Smith, Brian J. (2002). "Calculation of aqueous dissociation constants of 1,2,4-triazole and tetrazole: A comparison of solvation models". Phys. Chem. Chem. Phys. 4 (18): 4314–4318. Bibcode 2002PCCP....4.4314S. doi:10.1039/b203118c.