24.9 Organic chemistry and biochemistry
The Swedish chemist Jöns Berzelius (1807-1882) appears to have introduced the name “organic chemistry” for the study of molecules derived from living things. This appears to imply that living stuff is different to non-living stuff. In post 16.18, I explain my reasons for believing that this apparent implication isn’t true. Even in Berzelius’ lifetime, many scientists appear not to have believed it. So there was no single point in time at which scientists would have believed that molecules from living sources were somehow special.
But an experiment that clearly showed that molecules from living things weren’t special was performed by the chemist Friedrich Wöhler (1779-1848) who lived and worked in what is now Germany. He was the first to synthesise an organic compound (urea) from an inorganic compound (ammonium cyanate). Ammonium cyanate is a mixture of ammonium ions and cyanate ions (formulae I in the picture above) and can be synthesised from substances that don’t come from living things. Urea (formula II) is found in urine and other body fluids and we make it when we break down proteins. Although many books consider this experiment to be important for understanding that there was nothing special about organic molecules, it’s not clear whether this was Wöhler’s intention. But as a result, the name “organic chemistry” changed its meaning.
Now organic chemistry means the synthesis and investigation of molecules containing carbon because nearly all the molecules processed by living things contain carbon. There seem to be about 100 million known different molecules that contain carbon atoms and new ones are being discovered all the time. Many are synthesised for the first time in the development of pharmaceutical and other industrial products. These molecules may contain carbon atoms bonded to each other (like ethanol, the “alcohol” in alcoholic drinks, formula III above), perhaps forming chains as in isoprene (formula IV above) and may join to form polymers like nylon (formula V above) and PVC (formula VI above). In others, the carbon atoms form rings: a few examples include cytosine (formula VII below), adenine (formula VIII below), fructose (formula IX below) and sucrose (formula X below). If you don’t understand chemical formulae like VII, VIII, IX and X, see post 20.38 for an explanation.
