Nobel Prize in Chemistry 2026: The Nobel Prize in Chemistry 2026 has been awarded to Henri B Kagan and Kenso Soai “for the discovery of non-linear effects and autocatalysis in asymmetric organic synthesis”.For those who found this line almost incomprehensible, the scientists work led to the creation of a way to produce more of one type of molecules and less of its mirror image in chemical reactions where the product was the same as the catalysis, the agent causing the reaction.A reaction of this sort had been one of Chemistry’s most famous puzzles for years, and when Soai finally came up with the reaction, called Soai’s reaction, it was considered one of the most elegant chemical experiments ever.Why were scientists so concerned about mirror images of molecules? To answer an old and engrossing question: why life overwhelmingly chooses one sort of molecule when its mirror image exists.Chiral moleculesThe Nobel Prize’s official press release explains chiral molecules using the example of a lock and key. Imagine making a key for a lock, only to discover that your manufacturing process produces two keys that are mirror images of each other. They look almost identical, but only one fits the lock. The other may do nothing — or, in some cases, cause damage.This is roughly the problem chemists face with chiral molecules. Many molecules can exist in two forms that are mirror images of each other, known as enantiomers. They have the same chemical composition, but their three-dimensional arrangements are different.The mystery of life’s one-handed chemistryThe story goes back to Louis Pasteur (of the rabies vaccine fame), who was studying tartaric acid, found in grapes and thus in wine, in the mid-19th century.Story continues below this adPasteur found that tartaric acid crystals existed in two forms that were mirror images of each other. But bacteria that fermented tartaric acid consumed only one of its enantiomers — the one found in grapes— and left its mirror image untouched.This pointed towards a much bigger mystery: life itself appeared to be one-handed.When scientists later examined life’s building blocks, they found that naturally occurring amino acids bend polarised light to the left, while sugars found in DNA bend it to the right. In other words, life overwhelmingly uses one of two possible mirror-image forms.Why? When chemists tried making chiral molecules in the laboratory, they generally obtained an equal mixture of the two enantiomers. So what happened at the dawn of life that made biological chemistry choose one?Marckwald makes the first breakthroughStory continues below this adThe next important step came in the early 1900s, when German chemist Willy Marckwald carried out the first successful asymmetric reaction.An asymmetric reaction is simply one in which more of one enantiomer is produced than the other. In Marckwald’s experiment, the difference was small, and did not explain how such an imbalance could become much larger.Charles Frank adds the theoryIn 1953, Charles Frank, a theoretical physicist at the University of Bristol, provided the next crucial link.Frank proposed a mathematical model for how homochirality could arise. His idea required three things.First, there had to be a chiral catalyst and an asymmetric reaction. Second, the formation of one mirror image had to be enhanced while the other was suppressed. Third, the reaction had to produce the catalyst itself.The third condition is called autocatalysis.Autocatalysis creates a kind of chemical snowball effect. Imagine that a reaction produces a tiny excess of one molecular form. If that form can then help make more of itself, the initial imbalance can grow rapidly.Story continues below this adFrank’s model became a famous chemical puzzle: could anyone actually create a reaction that fulfilled all three conditions?Henri Kagan finds the missing pieceThis is where Henri B. Kagan enters the story.In the 1980s, Kagan was working on asymmetric reactions, with the aim of producing enantiomers as purely as possible — something particularly important in pharmaceutical manufacturing.Chemists commonly used catalysts containing a metal atom and a chiral substance. They assumed that if the catalyst contained equal amounts of the two mirror-image forms, the resulting product would also contain equal amounts of its two enantiomers.Kagan questioned this assumptionStory continues below this adHe realised that the metal atom might interact with at least two chiral molecules at the same time. If both forms were present, this could produce three kinds of catalyst: one containing two molecules of one handedness, one containing two of the other, and a mixed form.The crucial discovery was that the mixed catalyst behaved differently. It drove the reaction much more slowly than the other two.This meant that the relationship between the handedness of the catalyst and that of the final product was not linear.In 1986, Kagan described three asymmetric reactions displaying these non-linear effects. He had supplied the second missing piece of Frank’s model: a way to amplify an initial asymmetry.Story continues below this adKenso Soai makes the chemistry self-reinforcingThe final step came from Kenso Soai at the Tokyo University of Science.Soai was studying an asymmetric reaction that showed a strong non-linear effect. He noticed similarities between the catalyst and the product and wondered whether he could design a reaction in which the catalyst actually produced itself.In the early 1990s, Soai experimented with many molecules before finding one that could do this: 5-pyrimidyl alkanol. In a 1995 experiment, he began with just a 2 per cent excess of one enantiomer and ended with an 87 per cent excess. The reaction was self-reinforcing: the slight initial advantage became a much larger one.But Soai continued searching for something even more striking.In 2003, he presented a reaction in which an excess of one enantiomer was formed and that enantiomer then helped produce copies of itself. This became known as the Soai reaction.Why does this matter?As the Nobel press release says, “The non-linear effects that Kagan discovered have become an important tool for chemists when they design new reactions. The fact that a reaction is non-linear provides chemists with information about how it occurs. This information can be used to optimise the reaction, so they can obtain the purest possible enantiomers of the product. This is vital for every company that manufactures substances that are intended to interact with living beings, such as pharmaceuticals, flavours, scents and agricultural chemicals.”