Gamechanging reactions
Source: By Amitabh Sinha: The Indian Express
Simple ideas are often the most difficult to imagine,” the Nobel Prize committee said while honouring Benjamin List and David MacMillan with this year’s Chemistry Nobel.
The simple idea that List and MacMillan came up with, working independently, was to look for new catalysts, the substances used to accelerate chemical reactions, when most believed they were stuck with an existing, somewhat inefficient, set.
The new catalysts, derived from naturally-occurring chemicals, were greener and cheaper, and ensured that the end product of the chemical reaction was of a specific variety — and did not need to go through a purification process to yield the desired type of compound.
“The discovery being awarded the Nobel Prize in Chemistry 2021 has taken molecular construction to an entirely new level,” the Nobel committee said. “Its uses include research into new pharmaceuticals and it has also helped make chemistry greener.”
Catalysts
When two or more compounds react to form new compounds, the process is often aided by other chemicals that do not change themselves, but help speed up the reaction. These catalysts have been known at least since the middle of the 19th century, and are used in virtually every chemical process these days.
Till around 2000, only two kinds of chemicals were known to act as effective catalysts: metals, mainly heavier metals; and enzymes, naturally-occurring heavy molecules that facilitate all life-supporting biochemical processes. Both these sets of catalysts had limitations.
Heavier metals are expensive, difficult to mine, and toxic to humans and the environment. Despite the best processes, traces remained in the end product; this posed problems in situations where compounds of very high purity were required, like in the manufacture of medicines. Also, metals required an environment free of water and oxygen, which was difficult to ensure on an industrial scale.
Enzymes on the other hand, work best when water is used as a medium for the chemical reaction. But that is not an environment suitable for all kinds of chemical reactions.
