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Kagan and Soai win 2026 Chemistry Nobel for mirror-molecule work

By CAShorts DeskPublished Updated Sources: NobelPrize.org; The Hindu; AP

Kagan and Soai win 2026 Chemistry Nobel for mirror-molecule work
Illustration (AI-generated)

French chemist Henri Kagan and Japanese chemist Kenso Soai have won the 2026 Nobel Prize in Chemistry for discovering non-linear effects and autocatalysis in asymmetric organic synthesis. The two will share the prize equally. Their research shows how chemical reactions can magnify a tiny imbalance between mirror-image molecules into an overwhelming one.

Syllabus: Prelims · Current Affairs & IR; Prelims · Science & Technology; GS3 · Science & Technology

Why it matters

A patient taking a medicine often swallows a chiral drug. One mirror-image form does the healing; its twin can cause unwanted, sometimes harmful side effects, because the body's enzymes and receptors are themselves chiral. The Academy recalls the thalidomide scandal of the early 1960s, when a sedative left thousands of children with birth defects and the harm was traced to the mirror image of the active substance. Smell differs too: one form of carvone smells of mint, the other of caraway. Kagan's insight helps chemists design reactions giving the purest form of a drug, flavour, scent or farm chemical. Soai's reaction shows that a tiny chance imbalance can snowball into near-total one-handedness without any living cell, though the Academy calls it a proof of concept, not life's own route.

Prelims pointers

  • Chiral molecule: exists as two non-superimposable mirror-image forms (enantiomers) with the same atoms and bonding order but a different 3D arrangement.
  • Enantiomers have identical melting and boiling points but rotate plane-polarised light by equal amounts in opposite directions; a racemic mixture, with equal amounts of both, shows no net rotation.
  • Proteins use L-amino acids and DNA and RNA use D-sugars; D and L name the spatial arrangement, not the direction of optical rotation (D-fructose rotates light to the left).
  • Asymmetric reaction: one that yields more of one enantiomer than the other; enantiomeric excess measures by how much one form outnumbers its mirror image.
  • Autocatalysis: a reaction whose product acts as the catalyst for that same reaction, so an initial imbalance can snowball.
  • A catalyst speeds up a reaction without itself being consumed in it.
  • Match the names: Pasteur (tartaric acid), Marckwald (first asymmetric reaction), Frank (1953 model), Kagan (non-linear effects), Soai (asymmetric autocatalysis).
  • The Royal Swedish Academy of Sciences awards the Chemistry Nobel; earlier prizes for asymmetric catalysis went to Knowles, Noyori and Sharpless (2001) and to List and MacMillan (2021).

Practise a UPSC-style question

With reference to chiral molecules, consider the following statements:

1. The two enantiomers of a chiral molecule have the same atoms joined in the same order but a different 3D arrangement.

2. A racemic mixture contains equal amounts of two enantiomers and shows no net rotation of plane-polarised light.

3. The two enantiomers of a chiral compound have different boiling points and different melting points.

Which of the statements given above is/are correct?

  1. (a) 1 and 2 only
  2. (b) 2 and 3 only
  3. (c) 1 and 3 only
  4. (d) 1, 2 and 3
Show the answer

Answer: (a) 1 and 2 only

1 is correct: enantiomers are non-superimposable mirror images with identical atoms and bonding order, differing only in 3D layout. 2 is correct: the two forms rotate plane-polarised light by equal amounts in opposite directions, so an equal mix shows no net rotation. 3 is incorrect: enantiomers have identical boiling and melting points; they differ in how they rotate polarised light and interact with other chiral molecules.

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