Skeletal formula of hydantoin
Ball-and-stick model of hydantoin
IUPAC name
461-72-3 YesY
3D model (Jmol) Interactive image
ChEBI CHEBI:27612 YesY
ChEMBL ChEMBL122334 YesY
ChemSpider 9612 YesY
ECHA InfoCard 100.006.650
KEGG C05146 YesY
PubChem 10006
Molar mass 100.08 g·mol−1
Melting point 220 °C (428 °F; 493 K)
39.7 g/L (100 °C)
Except where otherwise noted, 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 with the formula CH2C(O)NHC(O)NH. It is a colorless solid that arises from the reaction of glycolic acid and urea. It is an oxidized derivative of imidazolidine. In a more general sense, hydantoins can refer to a groups and a class of compounds with the same ring structure as the parent. 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 synthesized 5-methylhydantoin from alanine sulfate and potassium cyanate in what is now known as the Urech hydantoin synthesis[2] The method is very similar to the modern route using alkyl and arylcyanates. 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". The cyclic structure of hydantoins was confirmed by Dorothy Hahn 1913.[6]

Of practical importance, hydantoins are obtained by condensation of a cyanohydrin with ammonium carbonate. Another useful route, which follows the work of Urech, involves the condensation of amino acids with cyanates and isocyanates:

Uses and occurrence


Hydantoin group can be found in several medicinally important compounds. In pharmaceuticals, 'hydantoins' most often refer to anticonvulsants; phenytoin and fosphenytoin both contain hydantoin moieties and are both used as anticonvulsants in the treatment of seizure disorders. The hydantoin derivative dantrolene is used as a muscle relaxant to treat malignant hyperthermia, neuroleptic malignant syndrome, spasticity, and ecstasy intoxication. Ropitoin is an example of an antiarrhythmic hydantoin.


The hydantoin derivative Imiprothrin is a pyrethroid insecticide. Iprodione is a popular fungicide containing the hydantoin group.[7]

Synthesis of amino acids

Hydrolysis of hydantoins affords amino acids:


Hydantoin itself reacts with hot, dilute hydrochloric acid to give glycine. Methionine is produced industrially via the hydantoin obtained from methional.[7]


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).

Iprodione is a popular fungicide containing the hydantoin group.

DNA Oxidation to hydantoins after cell death

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.[8]


  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. Oakes, Elizabeth H. (2007). Encyclopedia of World Scientists. Facts on File, Incorporated. p. 298. ISBN 9780816061587.
  7. 1 2 Karlheinz Drauz, Ian Grayson, Axel Kleemann, Hans-Peter Krimmer, Wolfgang Leuchtenberger, Christoph Weckbecker (2005), "Amino Acids", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a02_057.pub2
  8. 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 domain: Chisholm, Hugh, ed. (1911). "article name needed". Encyclopædia Britannica (11th ed.). Cambridge University Press. 

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