Nobel and other Prizes

Chemistry Nobel to duo for developing Organo-Catalysis

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Nobel Price, BioCatalysts

Mains level : NA

The Nobel Prize for chemistry has been awarded to German scientist Benjamin List of the Max Planck Institute and Scotland-born scientist David WC MacMillan of Princeton University for their work on developing an organo-catalyst.

What are 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.

Issues with conventional catalysts

  • 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.

Nobel invention: Organo-catalysis

  • List and MacMillan, the both, started experimenting with simple organic compounds.
  • Organic compounds are mostly naturally occurring substances, built around a framework of carbon atoms and usually containing hydrogen, oxygen, nitrogen, sulfur, or phosphorus.
  • Life-supporting chemicals like proteins, which are long chains of amino acids (carbon compounds containing nitrogen and oxygen) are organic.
  • Enzymes are also proteins, and therefore, organic compounds.
  • List and MacMillan started working with individual amino acids in enzymes — and struck gold.

What are asymmetric catalysis?

  • Substances can have exactly the same chemical composition and molecular formula; yet differ widely in their properties. They are known as isomers.
  • One type of isomers are those that differ in the way individual atoms are oriented in three-dimensional space.
  • Two molecules could be exactly the same, except that they are mirror images of each other, like our hands.
  • For simplicity, scientists often refer to these molecules as left-handed or right-handed.
  • This simple difference can sometimes have enormous consequences because it allows the molecules to bind in different locations when they interact with other molecules.
  • The end product in a chemical reaction is usually a mixture of left-handed and right-handed molecules.
  • List and MacMillan discovered that by using a natural compound like an amino acid as a catalyst, they were obtaining only one specific mirror image of the end-product.
  • This was later named asymmetric catalysis.

Significance of their discovery

  • 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.
  • The end product need not 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.
  • Its uses include research into new pharmaceuticals and it has also helped make chemistry greener.

 

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