Organic chemistry refers to compounds containing the chemical element carbon, and usually a combination of hydrogen and oxygen. ‘Organic’ describes the fact that many of these compounds are found in plants and animals. For example, glucose (chemical formula C6H12O6) is a simple sugar made in photosynthesis that helps to keep most cells alive, as well as being the basic ‘building block’ for more complicated sugars such as sucrose, starch and cellulose.

The eighteenth-century Swedish chemist Carl Wilhelm Scheele was probably the first person in Europe to isolate organic compounds from plant and animal sources. He showed that milk turns sour because of the compound lactic acid. At that time, chemists believed organic compounds could only be made in reactions in cells, by means of a ‘life force’.

This had to change after 1828, when the German chemist Friedrich Wohler made urea, the compound excreted in animal urine, by heating a solution of the inorganic compound ammonium cyanate: NH4CNO → CO(NH2)2 This prompted the understanding that organic compounds could be synthesised in laboratories, leading to the development of ‘biochemistry’ as the specialist branch of chemistry investigating reactions in living cells and life processes.