Biuret

Biuret is a condensation compound of urea, equivalent to two molecules of urea less one of ammonia. It is a white solid soluble in hot water and decomposes at 186–189 °C. The parent compound can be prepared by heating urea above the melting point at which temperature ammonia is expelled.


 * 2 CO(NH2)2 → H2N-CO-NH-CO-NH2 + NH3 ↑

A biuret is also a functional group and a class of organic compounds with the general structure RHundefinedN-CO-NR-CO-NHundefinedR where R is an organic residue. Biurets can be prepared by trimerization of isocyanates. For example the trimer of 1,6-hexamethylene diisocyanate is also known as HDI-biuret.

The biuret reagent is used in the biuret protein assay, a chemical test for proteins not because the reagent contains biuret but because both biuret and proteins have the same response to copper.