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Skeletal formula of hydantoin Ball-and-stick model of hydantoin
CAS number 461-72-3 YesY
PubChem 10006
ChemSpider 9612 YesY
KEGG C05146 YesY
ChEBI CHEBI:27612 YesY
Jmol-3D images Image 1
Molecular formula C3H4N2O2
Molar mass 100.076
Melting point 220°C
Solubility in water 39.7 g/L (100°C)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Hydantoin, or glycolylurea, is a heterocyclic organic compound that is a cyclic "double-condensation reaction" product of glycolic acid and urea. Its chemical structure, shown in the Table of Properties at right, is similar to that of imidazolidine except that the molecule of hydantoin has carbonyl groups in the number 2 and 4 positions in the ring. Imidazolidine is the hydrogen-saturated analogue of imidazole.

In a more general sense, hydantoins can refer to chemical compounds that have substituent groups bonded to a hydantoin ring skeletal structure. For example, phenytoin (mentioned below) has two phenyl groups substituted onto the number 5 carbon in a hydantoin molecule.[1]


Hydantoin was first isolated in 1861 by Adolf von Baeyer in the course of his study of uric acid. He obtained it by hydrogenation of allantoin, hence the name. Urech in 1873 [2] synthesized the derivative 5-methylhydantoin from alanine sulfate and potassium cyanate in what is now known as the Urech hydantoin synthesis:

Urech Hydantoin synthesis

The 5,5-dimethyl compound can also be obtained from acetone cyanohydrin (also discovered by Urech: see cyanohydrin reaction) and ammonium carbonate.[3] This reaction type is called the Bucherer–Bergs reaction.[4][5]

According to the 1911 Encyclopædia Britannica, hydantoin can also be synthesized either by heating allantoin with hydroiodic acid or by "heating bromacetyl urea with alcoholic ammonia".


Medicines and Pharmaceuticals[edit]

Hydantion moieties can be found in several medicinal molecules. In pharmaceuticals, 'hydantions' most often refer to anticonvulsants; phenytoin and fosphenytoin both contain hydantion moieties and are both used as anticonvulsants in the treatment of seizure disorders. The hydantion derivative Dantrolene is used as a muscle relaxant in malignant hyperthermia, and is also used in neuroleptic malignant syndrome, spasticity, and ecstasy intoxication.

Chemical derivatives[edit]

When hydantoin reacts with hot, dilute hydrochloric acid, glycine is one of the products.

Some N-Halogenated derivatives of hydantoin are used as chlorinating or brominating agents in disinfectant/sanitizer or biocide products. The three major N-halogenated derivatives are dichlorodimethylhydantoin (DCDMH), bromochlorodimethylhydantoin (BCDMH), and dibromodimethylhydantoin (DBDMH).

DNA Oxidation to hydantoins after cell death[edit]

A high proportion of cytosine and thymine bases in DNA are oxidized to hydantoins over time after the death of an organism. Such modifications block DNA polymerases and thus prevents PCR from working. Such damage is a problem when dealing with ancient DNA samples.[6]

External links[edit]


  1. ^ The Chemistry of the Hydantoins.Elinor Ware Chem. Rev.; 1950; 46(3) pp 403 - 470; doi:10.1021/cr60145a001
  2. ^ Urech, Ann., 165, 99 (1873).
  3. ^ Organic Syntheses, Coll. Vol. 3, p.323 (1955); Vol. 20, p.42 (1940) Link.
  4. ^ Bucherer and Steiner, J. prakt. Chem., 140, 291 (1934).
  5. ^ Bergs, Ger. pat. 566,094 (1929) [C. A., 27, 1001 (1933)].
  6. ^ Hofreiter M., Serre D., Poinar H.N., Kuch M., and Paabo S. Nature Reviews Genetics (2001) 2:353.

Public Domain This article incorporates text from a publication now in the public domainChisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press.