The Nobel Prize in Chemistry this year goes to Henri Kagan and Kensō Soai, whose pioneering research transformed how crucial molecules are synthesized and helped shape modern pharmaceuticals. The Royal Swedish Academy of Sciences honored them for discovering nonlinear effects and autocatalysis in asymmetric organic synthesis, work that the committee’s chair, Heiner Linke, said solved a century-old puzzle: how homochirality can arise spontaneously.
Kagan, 95, a professor emeritus at Université Paris-Sud, is widely seen as the father of asymmetric catalysis. Soai, born in 1950, teaches applied chemistry at the Tokyo University of Science. Reached by phone in Hiroshima, he described the news as one of the most exciting moments of his life and said he was honored to share the prize with Kagan.
A world in the mirror
Many molecules come in two forms that mirror each other, like left and right hands: alike in appearance, yet impossible to superimpose. This property is called chirality. Life on Earth has chosen sides, building proteins from “left-handed” amino acids and DNA from “right-handed” sugars, a uniformity essential for organisms to function.
The distinction matters in practice. One form of carvone smells of spearmint, its mirror image of caraway, because our smell receptors are chiral too. Committee member Peter Somfai noted that one version of a drug molecule was sold as a cough suppressant and its mirror twin as a painkiller, with brand names that are themselves reversed, a nod to chemists’ sense of humor. The challenge was making a reaction produce just one “hand.”
From Kagan to the Soai reaction
Chemists long assumed a catalyst passes on its purity in a linear way, so an impure catalyst yields an equally impure product. Kagan overturned that view. Working with the Sharpless epoxidation, he showed that a product can emerge purer than the catalyst that made it, a positive nonlinear effect that became a core tool in the field.
Soai went further, asking whether asymmetry could appear from nothing. In 1995 he described asymmetric autocatalysis, in which a product speeds up its own formation. Starting from symmetric material with no chiral catalyst, he ran 37 experiments: 19 favored the left-handed form, 18 the right, and none produced an even mix. In another test, a nearly neutral catalyst yielded practically pure product within three cycles, amplifying the asymmetry 630,000-fold. Somfai hailed it as perhaps the coolest experiment in organic chemistry.
Nobel week continues
The Medicine and Physics prizes were announced earlier this week. Literature follows Thursday, Peace on Friday and Economics next Monday. Each prize carries 12 million Swedish kronor, about 1.2 million dollars.
