The big news of the day was that the Nobel Prize in Chemistry went to researchers who were indisputably chemists. The award was split three ways: Richard Heck (Delaware), Ei-ichi Negishi (Purdue), Akira Suzuki (Hokkaido) for palladium catalysis. This prize is awarded for a research that gets to the very heart of chemistry – making new molecules or making known molecules better. There are several challenges in the synthesis of small molecules, and one is putting elements together in a manner of our choosing. It may surprise some to know that not all the molecules have been made yet and that considerable quantities of time and money go each year towards the synthesis of new molecules that might have useful properties – perhaps as drugs, new additives for high performance materials, or for electronic applications.
You may think that the periodic table provides chemists with the ultimate lego set but actually forming certain kinds of bonds is rather difficult and requires special reaction conditions. Notably, carbon-carbon bonds are quite difficult to form. With a few glorious exceptions (such as cisplatin) medicinal compounds have carbon skeletons. These might be isolated from natural sources and modified (like aspirin from willow bark) or synthesised in the laboratory, but in all cases it may require the formation of new carbon-carbon bonds. Heck, Negishi and Suzuki provided chemists with new tools, new reactions to form such bonds using the palladium compounds as catalysts. Heck reactions produce carbon-carbon double bonds that are ripe for subsequent reactions. Negishi couplings form carbon carbon bonds linking two different molecules together using an organozinc compound and a palladium catalyst. Suzuki couplings use derivatives of organic molecules with boron to form carbon carbon bonds, again with a palladium catalyst.
Now you may well ask why we need three methods of forming carbon-carbon bonds with a palladium catalyst. Simply, different chemicals behave differently under different reaction conditions. Often chemists must try a wide range of reagents and reaction types before getting the desired result – that is one of the true skills of being a chemist. It isn’t so different to making a recipe multiple times before you feel you’ve got the seasoning just perfect. These reactions are superb tools for chemists to synthesise new molecules with the potential to be drugs, dyes in display screens or useful in applications that we cannot yet dream of.
Anyway, I’m just happy that the prize is pure chemistry and long overdue to the recipients.