NOBEL PRIZE IN CHEMISTRY 2026 2026 Nobel Prize in Chemistry: Henri B. Kagan and Kenso Soai Two chemists who showed how to make just one of a molecule's two mirror images. |
What did they win the Nobel Prize for? They share the 2026 Nobel Prize in Chemistry for the discovery of nonlinear effects and autocatalysis in asymmetric organic synthesis. |
The prize at a glance
| Henri B. Kagan | Kenso Soai | |
| Nationality | France | Japan |
| Age | 95 | 76 |
| Affiliation | Université Paris-Sud | Tokyo University of Science |
| Key discovery | Nonlinear effect (1986) | Asymmetric autocatalysis, the Soai reaction (1995) |
| Prize motivation | For the discovery of nonlinear effects and autocatalysis in asymmetric organic synthesis |
| Announced | October 7, 2026, Royal Swedish Academy of Sciences |
| Prize amount | SEK 12 million, shared equally |
An illustration symbolizing mirror-image molecules.
Molecules that cannot be superimposed, like left and right hands
A chiral molecule is one whose mirror image cannot be superimposed on it, even though both contain the same atoms.
Your left and right hands have the same fingers, yet no matter how you turn them they never overlap. Molecules behave the same way: when a carbon atom carries four different groups, two mirror-image forms exist. These are called enantiomers.
Why only one mirror form is needed
Living organisms use almost exclusively one mirror form.
The amino acids in proteins and the sugars in genetic material all share a single handedness. That is why the two mirror forms of a drug can act completely differently in the body. The Nobel Committee noted that one form may have the therapeutic effect while the other can cause unnecessary or even harmful side effects.
Ordinary chemical reactions produce a 50:50 mixture of the two forms. Making only the desired one is called asymmetric synthesis, and the two laureates solved a long-standing puzzle in this field.
An illustration of an asymmetric synthesis laboratory.
Henri Kagan — a product purer than its catalyst
In 1986, Kagan showed that the purity of a catalyst and the purity of its product are not simply proportional.
Chemists had assumed that a catalyst containing 70 percent of one mirror form would give a product in the same proportion. Kagan showed that the relationship is not a straight line: depending on the system, the product can be purer than the catalyst, or less pure. This is the nonlinear effect.
The cause lies in catalyst molecules pairing up. When minority-form molecules bind to majority-form molecules and drop out of the reaction, the remaining majority catalyst dominates and the product becomes purer. The discovery meant that high-purity products could be made even with imperfect catalysts.
Kenso Soai — a reaction whose product multiplies itself
In 1995, Soai reported a reaction in which the product acts as a catalyst for its own formation.
Adding diisopropylzinc to pyrimidine-5-carbaldehyde produces pyrimidyl alkanol, a chiral molecule. Remarkably, this product catalyzes the formation of more of its own mirror form. If one form is even slightly more abundant, it multiplies faster and faster.
Starting from an enantiomeric excess of only about 0.00005 percent, Soai reached more than 99.5 percent in just three consecutive reactions, while the amount of product grew about 630,000-fold. In 2003 he reported a reaction that produced only one mirror form without any external chiral material.
An illustration of quartz crystals, which can trigger the Soai reaction.
Approaching the mystery of life's origin
Why life came to use only one mirror form is a question more than a century old.
Soai demonstrated experimentally that tiny asymmetric triggers such as circularly polarized light, quartz crystals or isotopes can be greatly amplified by autocatalysis. If such amplification happened on the early Earth, it could explain how only one mirror form survived.
An illustration of the early Earth before life began.
Why a Nobel Prize
| Perspective | Significance |
| Basic chemistry | Changed our understanding of how catalysts work in asymmetric reactions |
| Medicine | A foundation for making exactly the desired mirror form, improving efficacy and reducing side effects |
| Origin of life | Showed a real chemical pathway from a tiny bias to a nearly pure single form |
Twenty-five years after the 2001 Nobel Prize in Chemistry honored catalytic asymmetric synthesis, the field has been recognized again. The two laureates gave fundamental answers to why and how asymmetric synthesis works.
| First Penguin Coffee Company First Penguin Coffee Company explains even the chemical reactions that create coffee flavor through evidence. The laureates' finding that a tiny difference can grow into a large outcome mirrors how a single small adjustment in roasting can change the taste of a coffee. |
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