Biuret

Structural formula
General
Surname	Biuret
other names	Carbamoyl urea; Imidodicarboxylic acid diamide; Allophanoic acid amide;
Molecular formula	C 2 H 5 N 3 O 2
Brief description	colorless, hygroscopic crystals
External identifiers / databases
EC number	203-559-0
ECHA InfoCard	100.003.236
PubChem	7913
ChemSpider	7625
Wikidata	Q414902
properties
Molar mass	103.09 g mol −1
Physical state	firmly
density	1.47 g cm −3
Melting point	188–190 ° C (decomposition)
solubility	little in water (20 g l −1 at 20 ° C); good in hot water and alcohol; little in ether;
safety instructions
GHS labeling of hazardous substances	no GHS pictograms
	no GHS pictograms
H and P phrases	H: no H-phrases
	P: no P-phrases
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Biuret [ biuˈreːt ] is an organic compound from the group of carboxamides , which is derived from the unstable allophanoic acid ( carbamoylcarbamic acid H ₂ N – CO – NH – COOH). Biuret is produced during the pyrolysis of urea by condensation of two molecules of urea with splitting off of one molecule of ammonia .

presentation

Biuret is formed when urea is heated with the elimination of ammonia:

In addition to biuret, small amounts of triuret and melamine are also produced .

Properties and evidence

Biuret is a colorless, crystalline, water-attracting substance, which dissolves little in cold water or ether, but well in hot water ( better in acidic and basic than in neutral due to weak ampholyter properties). Biuret partially turns into melamine when heated. When biuret decomposes above 188 ° C, cyanuric acid and ammonia can also form nitrogen oxides , carbon monoxide and carbon dioxide . Biuret is toxic to plants; even small amounts (50–150 ppm in the nutrient solution) cause chlorosis .

A purple complex forms with copper (II) ions in an alkaline medium . A similar hue can be observed in the so-called biuret reaction with proteins . Here, instead of biuret, the peptide groups act as ligands for the copper ion. This reaction can be used for the detection of proteins in aqueous solutions . In clinical diagnostics, for example, the biuret method according to Weichselbaum can be used to determine the total protein in body cavity effusions ( transudates and exudates ).

use

There is no known industrial use of biuret.

Biuret is present as an impurity in every manufactured urea. When using urea as a fertilizer, the content of biuret is limited (usually less than 1%), as this has an inhibiting effect on healthy plant growth.

Individual evidence

↑ ^a ^b ^c Entry on Biuret. In: Römpp Online . Georg Thieme Verlag, accessed on September 30, 2014.
↑ ^a ^b ^c ^d ^e Entry on biuret in the GESTIS substance database of the IFA , accessed on July 16, 2020(JavaScript required) .
↑ European Pharmacopoeia , Deutscher Apotheker Verlag Stuttgart, 6th edition, 2008, p. 543, ISBN 978-3-7692-3962-1 .
^ ^A ^b Haas, ARC, Brusca, JN: Biuret, Toxic Form of Nitrogen , California Agriculture, 1954 8 ( 6 ): 7, 11.

[roempp-1] Entry on Biuret. In: Römpp Online . Georg Thieme Verlag, accessed on September 30, 2014.

[GESTIS-2] Entry on biuret in the GESTIS substance database of the IFA , accessed on July 16, 2020(JavaScript required) .

[EuropäischesArzneibuch-3] European Pharmacopoeia , Deutscher Apotheker Verlag Stuttgart, 6th edition, 2008, p. 543, ISBN 978-3-7692-3962-1 .

[calagri-4] A ^b Haas, ARC, Brusca, JN: Biuret, Toxic Form of Nitrogen , California Agriculture, 1954 8 ( 6 ): 7, 11.