Organic compound (Latin urea), which must not be confused with uric acid. It is produced by many animals as the end product of the metabolism of nitrogen compounds such as amino acids and proteins and excreted in the urine. Pure urea is a white, crystalline, slightly ammonia-smelling, non-toxic and hygienically safe solid. The urea was discovered in 1773 and was the first organic compound, which was then produced in 1828 for the first time synthetically. This revolutionary invention contradicted the former belief that organic substances can only be produced by the so-called "vis vitalis" (life force) and was the beginning of organic chemistry. The urea, also known as carbonic acid diamide, is a so-called amide fertilizer in addition to calcium cyanide, because he nitrogen
in amide form (salts of ammonia). Due to its high nitrogen content of just under 50%, it is the world's most important nitrogen fertilizer (see also under fertilization
). Urea may be at the fermentation
in small quantities also enter the wine, where he longer term with ethanol
to ethyl carbamate
responding. This substance is suspected to be carcinogenic in humans. If the amount of urea exceeds 1 mg / l for wines intended for longer storage, the enzyme may be used urease
the urea is split into ammonia and carbon dioxide and thus reduced.