How urea forms spontaneously

Summary

Urea is one of the most important industrial chemicals produced worldwide. It is used as a fertiliser, for the production of synthetic resins and explosives and as a fuel additive for cleaning car exhaust gases. Urea is also believed to be a potential key building block for the formation of biological molecules such as RNA and DNA in connection with the question of the origin of life (see ETH News from 28 June 2023). Until now, the origin of urea itself on Early Earth has not been conclusively clarified. A research team led by Ruth Signorell, Professor of Physical Chemistry at ETH Zurich, has discovered a previously unknown reaction pathway for the formation of urea that could provide an answer. The external page study has just been published in the journal Science. Chemistry on the water surface Either high pressures and temperatures or chemical catalysts are needed for the industrial production of urea from ammonia (NH₃) and carbon dioxide (CO₂). Enzymes enable the same reaction to take place in humans and animals, removing toxic ammonia from the breakdown of proteins such as urea. As this simple molecule contains nitrogen as well as carbon and probably existed on the uninhabited Early Earth, many researchers view urea as a possible precursor for complex biomolecules. “In our study, we show one way in which urea could have formed on the prebiotic Earth,” says Signorell – “namely where water molecules interact with atmospheric gases: on the water surface.”