Carbamide is an organic compound commonly known as urea, the primary byproduct of nitrogen metabolism in mammals and amphibians. It is characterized as a water-soluble, colorless, and odorless granular substance in its pure state, but in the presence of moisture, it will give off a slight ammonia smell.
Synthesized from ammonia and carbon dioxide in the liver, carbamide travels to the kidneys via the blood, where it is excreted in urine. This compound can also be made artificially from inorganic materials. Friedrich Wöhler was the first to make this discovery when he accidentally created it from potassium cyanate and ammonium sulfate in 1828.
Although Wöhler had intended to synthesize ammonium cyanate and not carbamide, his discovery nonetheless proved invaluable. Prior to this event, the scientific community held that the biochemistry of living things differed from non-organic matter and could not be duplicated. Known as the principle of vitalism, this concept stemmed from the belief that non-living things lacked the vital force, or the unknown element that sparks life. In effect, Wöhler contributed to setting this theory aside and paved the way for the study of organic chemistry.
Carbamide is a diamide of carbonic acid since it contains two amide groups. In addition, its synthesis is completed through an anabolic process, which requires the utilization of small molecules from other agents. In this case, carbon dioxide, aspartate, ammonia, and water provide the metabolic pathway. This process, known as the urea cycle, is vital to the elimination of ammonia, which would otherwise accumulate in toxic amounts.
Since this substance is inexpensively produced from synthetic ammonia and carbon dioxide, it is manufactured on a wide scale for a variety of commercial uses. Being a rich source of nitrogen, the majority is made for the fertilizer industry. It is also highly water-soluble due to its ability to form multiple hydrogen bonds. Once applied to soil, the compound quickly reverts into ammonia and carbon dioxide through hydrolysis.
Carbamide has several other applications. In veterinary medicine, for instance, it is used as a topical antiseptic and a diuretic. It is also sometimes used to enhance the protein content of cattle and sheep feed.
In manufacturing, it is used to make urea-formaldehyde plastics and carbamide resin as an adhesive for laminated plywood and particleboard. It is also used to stabilize explosives and, when combined with barium hydroxide, to deter the effects of acid rain when applied to limestone monuments. The compound was once used as a flame retardant for clothing and to induce the glycation process needed for commercial baked goods to brown. It's known by several trade names, including isourea, carbonyl diamide, and carbonyldiamine.