Biuret

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title: "Biuret" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["ureas", "functional-groups"] topic_path: "general/ureas" source: "https://en.wikipedia.org/wiki/Biuret" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

| Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 455517063 | Name = | ImageFile = Biuret.jpg | ImageFile_Ref = | ImageSize = 160 | ImageAlt = Freshly recrystallised biuret | ImageFile1 = Biuret struct.svg | ImageFile1_Ref = | ImageSize1 = 160 | ImageAlt1 = Skeletal formula of biuret | ImageFile2_Ref = | ImageSize2 = 160 | ImageAlt2 = Space-filling model of the biuret molecule | PIN = 2-Imidodicarbonic diamide | SystematicName = | OtherNames = | IUPACName = | Section1 = {{Chembox Identifiers | CASNo = 108-19-0 | CASNo_Ref = | UNII_Ref = | UNII = 89LJ369D1H | PubChem = 7913 | ChemSpiderID = 7625 | ChemSpiderID_Ref = | EINECS = 203-559-0 | KEGG = C06555 | KEGG_Ref = | MeSHName = Biuret | ChEBI = 18138 | ChEBI_Ref = | Beilstein = 1703510 | Gmelin = 49702 | 3DMet = B00969 | SMILES = NC(=O)NC(N)=O | StdInChI = 1S/C2H5N3O2/c3-1(6)5-2(4)7/h(H5,3,4,5,6,7) | StdInChI_Ref = | StdInChIKey = OHJMTUPIZMNBFR-UHFFFAOYSA-N | StdInChIKey_Ref = | Section2 = {{Chembox Properties | Formula = | C=2|H=5|N=3|O=2 | Appearance = White crystals | Odor = Odourless | Density = 1.467 g/cm3 | MeltingPt = 190 °C (decomposes) | Section3 = {{Chembox Thermochemistry | DeltaHf = (−565.8) – (−561.6) kJ/mol | DeltaHc = (−940.1) – (−935.9) kJ/mol | Entropy = 146.1 J/(mol·K) | HeatCapacity = 131.3 J/(mol·K) | Section4 = {{Chembox Hazards | GHSPictograms = | GHSSignalWord = WARNING | HPhrases = | PPhrases = | Section5 = {{Chembox Related | OtherCompounds = | Section6 = Biuret ( ) is a chemical compound with the chemical formula . It is a white solid that is soluble in hot water. A variety of organic derivatives are known. The term "biuret" also describes a family of organic compounds with the chemical formula , where are hydrogen, organyl or other groups. Also known as carbamylurea, it results from the condensation of two equivalents of urea. It is a common undesirable impurity in urea-based fertilizers, as biuret is toxic to plants.

Preparation and structure

The parent compound can be prepared by heating urea at 150 °C for ~6 hours until it gets slightly cloudy, then recrystallizing from water. After that, it can be recrystallized repeatedly from 2% sodium hydroxide solution and water to finally get base-free crystalline needles of the monohydrate which are free of cyanuric acid. While heating, a lot of ammonia is expelled: : Under related conditions, pyrolysis of urea affords triuret . In general, organic biurets (those with alkyl or aryl groups in place of one or more H atoms) are prepared by trimerization of isocyanates. For example, the trimer of 1,6-hexamethylene diisocyanate is also known as HDI-biuret.

In the anhydrous form, the molecule is planar and unsymmetrical in the solid state owing to intramolecular hydrogen bonding. The terminal C–N distances of 1.327 and 1.334 Å are shorter than the internal C–N distances of 1.379 and 1.391 Å. The C=O bond distances 1.247 and 1.237 Å. It crystallizes from water as the monohydrate.{{cite journal|journal=Acta Crystallogr.|year=1961|volume=14|issue=4|pages=345–352|doi=10.1107/S0365110X61001194 |title=The Crystal Structure of Biuret Hydrate |author=E. W. Hughes |author2=H. Yakel |author3=H. C. Freeman|doi-access=free}} 220 px|thumb|left|Structure of biuret in the solid state (blue = N, red = O, gray = C, cyan = H).

Use as feed

Biuret is used as a non-protein nitrogen source in ruminant feed, where it is converted into protein by gut microorganisms. It is less favored than urea, due to its higher cost and lower digestibility but the latter characteristic also slows down its digestion and so decreases the risk of ammonia toxicity.

Biuret test

The biuret test is a chemical test for proteins and polypeptides. It is based on the biuret reagent, a blue solution that turns violet upon contact with proteins, or any substance with peptide bonds. The test and reagent do not actually contain biuret; they are so named because both biuret and proteins have the same response to the test.

History

Biuret was first prepared and studied by Gustav Heinrich Wiedemann (1826–1899) for his doctoral dissertation, which was submitted in 1847. His findings were reported in several articles.

Related compounds

References

References

  1. (2014). "Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book)". [[Royal Society of Chemistry.
  2. |Allophanamide[[Scifinder]], version 2007.1; Chemical Abstracts Service: Columbus, OH; RN 108-19-0 (accessed June 15, 2012)
  3. Meessen, J. H.. "Urea".
  4. [http://www.britannica.com/eb/article-67947/livestock-farming Beef cattle feed], ''Encyclopædia Britannica'' Online
  5. (2013). "Florida Cow-Calf Management, 2nd Edition - Feeding the Cow Herd". IFAS Extension, University of Florida.
  6. (1969). "Urea versus biuret in a roughage diet for steers". [[Journal of Animal Science]].
  7. (1975). "Feed Grade Biuret as a Protein Replacement for Ruminants. A Review". Oxford University Press (OUP).
  8. Wiedemann, G.. (1848). "Ueber ein neues Zersetzungsproduct des Harnstoffs". Annalen der Physik.
  9. Wiedemann, G.. (1847). "Neues Zersetzungsproduct des Harnstoffs". Journal für Praktische Chemie.
  10. Wiedemann, G.. (1848). "Ueber eine neue, aus dem Harnstoff entstehende Verbindung". Journal für Praktische Chemie.
  11. Wiedemann, G.. (1848). "Biuret. Zersetzungsprodukt des Harnstoffs". Justus Liebig's Annalen der Chemie.

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