The chemistry Nobel goes to the scientists who showed how molecules pick a side

The 2026 Nobel Prize in Chemistry has been awarded to Henri B. Kagan and Kenso Soai for “the discovery of non-linear effects and autocatalysis in asymmetric organic synthesis,” the Royal Swedish Academy of Sciences announced on October 7. Kagan is associated with Université Paris-Saclay in France and Soai with the Tokyo University of Science in Japan. They will share the prize of 12 million Swedish kronor equally.

The puzzle of handedness

Many molecules exist in two forms that are mirror images of each other, like a left and a right hand. Chemists call this chirality. The two forms contain the same atoms in the same arrangement, yet they can behave very differently, especially inside the body. Living things use only one form of key building blocks such as amino acids and sugars, and how that one-sidedness arose has long puzzled chemists.

The difference matters in medicine. For many drugs, only one mirror-image form produces the intended effect; the other may do nothing or cause harm. Making medicines that contain only the right form requires reactions that strongly favor one hand over the other.

What Kagan found

In 1986, Kagan showed that the relationship between a catalyst’s handedness and the product’s handedness need not be a straight line. A catalyst that was only partly enriched in one form could produce a product more enriched than itself, an effect now called a nonlinear effect. It happens because the two forms of a catalyst can interact and differ in how reactive they are. The discovery gave chemists a way to understand, and exploit, how chiral catalysts amplify small differences.

What Soai found

Soai went a step further. In the reaction that now bears his name, reported in the mid-1990s, the product of the reaction acts as a catalyst for making more of itself, a process called autocatalysis, and it favors its own handedness as it does so. Starting from a mixture with only a minuscule excess of one form, repeated cycles in one widely cited version of the reaction produced material that was more than 99.5% a single form.

Experts note that the Soai reaction is a model system rather than a full explanation of how life’s handedness began on early Earth. But it was the first clear demonstration that chemistry alone can turn a whisper of asymmetry into near-total dominance.

Why it matters beyond the lab

The Academy highlighted that the work is now used by chemists who design reactions for drug manufacturing. Understanding how catalysts amplify handedness helps chemists build processes that deliver the one form of a molecule a medicine needs, more efficiently and with less waste. The laureates will receive their prizes at the traditional ceremony in Stockholm on December 10.