Biuret

This article is about the chemical compound. For the chemical test used to test for proteins, see Biuret test.
Not to be confused with burette.
Biuret
Skeletal formula of biuret
Ball-and-stick model of the biuret molecule
Space-filling model of the biuret molecule
Names
Preferred IUPAC name
2-Imidodicarbonic diamide
Systematic IUPAC name
(Carbamoylamino)methanamide
Other names
  • Allophanamide[1]
  • Carbamylurea[1]
  • Allophanic acid amide[1]
  • Allophanimidic acid[1]
  • N-Carbamoylaminomethanamide
  • Ureidoformamide[1]
  • Imidodicarbonic diamide
Identifiers
108-19-0 YesY
3D model (Jmol) Interactive image
Interactive image
3DMet B00969
1703510
ChEBI CHEBI:18138 YesY
ChemSpider 7625 YesY
ECHA InfoCard 100.003.236
EC Number 203-559-0
49702
KEGG C06555 YesY
MeSH Biuret
PubChem 7913
UNII 89LJ369D1H N
Properties
C2H5N3O2
Molar mass 103.08 g·mol−1
Appearance White crystals
Odor Odourless
Density 1.467 g/cm3
Melting point 190 °C (decomposes)
Thermochemistry
131.3 J K−1 mol−1
146.1 J K−1 mol−1
−565.8–−561.6 kJ mol−1
−940.1–−935.9 kJ mol−1
Hazards
GHS pictograms
GHS signal word WARNING
H315, H319, H335
P261, P305+351+338
Xi
R-phrases R36/37/38
S-phrases S26, S36
Related compounds
Related compounds
 urea, triuret, cyanuric acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

Biuret is a chemical compound with the chemical formula C2H5N3O2. It is also known as carbamylurea. It is the result of condensation of two molecules of urea and is an impurity in urea-based fertilizers. This white solid is soluble in hot water. 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.[2][3][4][5]

The term "biuret" also describes a family of organic compounds with the functional group -(HN-CO-)2N-. Thus dimethyl biuret is CH3HN-CO-NR'-CO-NHCH3. A variety of organic derivatives are possible.

Preparation

The parent compound can be prepared by heating urea above the melting point at which temperature ammonia is expelled:[6]

2 CO(NH2)2 → H2N-CO-NH-CO-NH2 + NH3

Under related conditions, pyrolysis of urea affords triuret ((H2N-CO-NH)2CO).[6] 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.

Applications

Biuret is also used as a non-protein nitrogen source in ruminant feed,[7] where it is converted into protein by gut microorganisms.[8] It is less favored than urea, due to its higher cost and lower digestibility[9] but this characteristic also slows down its digestion and so decreases the risk of ammonia toxicity.[9][10]

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.

References

  1. 1 2 3 4 5 Scifinder, version 2007.1; Chemical Abstracts Service: Columbus, OH; RN 108-19-0 (accessed June 15, 2012)
  2. ↑ Wiedemann, G. (1848). "Ueber ein neues Zersetzungsproduct des Harnstoffs" [On a new decomposition product of urea]. Annalen der Physik. 150 (5): 67–84. doi:10.1002/andp.18491500508.
  3. ↑ Wiedemann, G. (1847). "Neues Zersetzungsproduct des Harnstoffs" [New decomposition product of urea]. Journal für Praktische Chemie. 42 (3–4): 255–256. This notice reports that biuret reacts with alkaline copper sulfate to produce a red solution -- the so-called "Biuret test"
  4. ↑ Wiedemann, G. (1848). "Ueber eine neue, aus dem Harnstoff entstehende Verbindung" [On a new compound arising from urea]. Journal für Praktische Chemie. 43 (5): 271–280.
  5. ↑ Wiedemann, G. (1848). "Biuret. Zersetzungsprodukt des Harnstoffs" [Biuret: decomposition product of urea]. Justus Liebig's Annalen der Chemie. 68 (3): 323–326. doi:10.1002/jlac.18480680318.
  6. 1 2 Meessen, J. H.; Petersen, H. (2005), "Urea", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a27_333
  7. ↑ Beef cattle feed, Encyclopædia Britannica Online
  8. ↑ Kunkle, B.; Fletcher, J.; Mayo, D. (2013). "Florida Cow-Calf Management, 2nd Edition - Feeding the Cow Herd". IFAS Extension, University of Florida. Publication #AN117.
  9. 1 2 Oltjen, R. R.; Williams, E. E.; Slyter, L. L.; Richardson, G. V. (1969). "Urea versus biuret in a roughage diet for steers". Journal of Animal Science. 29 (5): 816–822. PMID 5391979.
  10. ↑ Fonnesbeck, P. V.; Kearl, L. C.; Harris, L. E. (1975). "Feed Grade Biuret as a Protein Replacement for Ruminants. A Review". Journal of Animal Science. 40 (6): 1150–1184.
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