Biuret

  • Biuret
  • Imidodicarbonsäurediamid
  • Allophansäureamid

Colorless, hygroscopic crystals

Fixed

1.47 g · cm -3

185-190 ° C ( decomposition)

Decomposition from 188 ° C

  • Little in water (20 g · l-1 at 20 ° C)
  • Well in hot water and alcohol
  • Little in ether

Attention

Template: Infobox chemical / molecular formula search available

Biuret [ biure ː t] is an organic compound from the group of carboxylic acid amides, derived from the unstable allophanic ( Carbamoylcarbamidsäure H2N -CO -NH- COOH). Biuret produced in the pyrolysis of urea by condensation of two molecules of urea with elimination of one molecule of ammonia.

Representation

Biuret is formed by heating urea with elimination of ammonia:

In addition small amounts of biuret occur triuret and melamine.

Properties and detection

Biuret is a colorless, crystalline, water-attracting substance that dissolves slightly in cold water or ether, well in hot water ( due to weak ampholyter properties in acidic and basic conditions better than in the neutrals ). Biuret upon heating partly in melamine. From the decomposition of biuret from 188 ° C also nitrogen oxides and carbon monoxide, and carbon dioxide may result in addition to cyanuric acid, and ammonia. In plants biuret is toxic; even small amounts ( 50-150 ppm in the nutrient solution ) can cause chlorosis.

With copper (II ) ions formed in an alkaline medium a violet complex. In the so-called proteins biuret with a similar color is observed. This function takes the biuret peptide groups as ligands for the copper ion. This reaction can be used for detection of proteins in aqueous solutions. So can be determined in clinical diagnosis by means of the biuret method according to Weichselbaum the total protein in body cavity effusions ( transudates and exudates ).

Use

There is no known industrial use of biuret.

Is biuret as an impurity in any industrially manufactured urea present. In the use of urea as a fertilizer of the biuret content is limited (usually less than 1% ), since this inhibiting effect on the healthy plant growth.

CAS registry number Dangerous Substances Directive (67/548/EEC) Amphoterism Hydrops
129600
de