Nobel Prize in Chemistry 2026,

[Astronuc]

Henri B. Kagan, Université Paris-Sud, France
Kenso Soai, Tokyo University of Science, Japan

“for the discovery of non-linear effects and autocatalysis in asymmetric organic synthesis”

They made chemistry choose a mirror image​

Some molecules, such as amino acids, exist as two variants that are each other’s mirror image. However, living organisms only contain one of these mirror images. How chemical asymmetry such as this could have emerged was long a mystery to chemists. Henri B. Kagan and Kenso Soai are awarded the Nobel Prize in Chemistry 2026 for discovering a solution to this puzzle.

https://www.nobelprize.org/prizes/chemistry/2026/press-release/

Life’s chemistry is what chemists call homochiral, after the Greek words for “same” and “hand”. Like hands, all amino acids exist as two mirrored variants, but only one of them is found in the proteins in your cells. The other is rarely found in nature.

For a long time, chemists wondered how homochirality can emerge. When they began to experiment with chemical reactions that can form two mirrored molecules, they always obtained equal proportions of both in their test tubes. However, chemists strived to produce only one of these mirror images, because in the development of molecules that will interact with living beings – such as in pharmaceuticals – only one mirror image will have the desired effect.

The Nobel Prize in Chemistry 2026 recognises discoveries that have enabled chemists to drive chemical reactions that lead to homochirality.

“Henri Kagan and Kenso Soai have provided a solution to a chemical mystery that is over a century old: how homochirality can emerge spontaneously. The chemical reactions they have developed are spectacular,” says Heiner Linke, chair of the Nobel Committee for Chemistry.

 

[BillTre]

This came as a surprise to me. Not something I have kept an eye out for.

 

[Mayhem]

This came as a surprise to me. Not something I have kept an eye out for.

It is not surprising to me! Enantioselectivity is one of the big bulls of synthetic chemistry.

 

[Astronuc]

I've known about right vs left (dextro vs levo) molecules since high school.

There was some speculation that l-glucose might be an alternative to d-glucose in combatting obesity. l-glucose is metabolized differently than d-glucose, or at least that was thinking about 50+ years ago.

https://unacademy.com/content/jee/study-material/chemistry/different-structural-forms-of-glucose/

Stereoisomers are isomers that differ in spatial arrangement of atoms, rather than order of atomic connectivity. One of their most interesting type of isomer is the mirror-image stereoisomers, a non-superimposable set of two molecules that are mirror image of one another. The existence of these molecules are determined by concept known as chirality.

https://chem.libretexts.org/Bookshe...mistry)/Chirality/Chirality_and_Stereoisomers

Biological Significance​

D-Glucose​

D-glucose (also known as dextrose) is the most biologically active and widely used monosaccharide. It serves as the primary energy source in most organisms, including humans, and is central to cellular respiration.

L-Glucose​

L-glucose has the same chemical formula and sweetness as D-glucose but is not recognized by the enzymes involved in glycolysis. It cannot be metabolized by most living organisms, making it a potential low-calorie sweetener, though its cost limits widespread use.

https://www.echemi.com/cms/967892.html

https://en.wikipedia.org/wiki/L-Glucose

https://en.wikipedia.org/wiki/Chirality_(chemistry)

 

[Borek]

This is basically kind of a process I remember being suggested even before their works (I learned about it in the early eighties, and I strongly doubt it was a fresh one then). The idea is that of a self-enforcing change: imagine you have a bag of black and white marbles. You draw three at random. If they are identical - return them. If one is different from two others: change its color and return three identical marbles to the bag. This is an unstable equilibrium - initially nothing happens, but at some point for purely statistical reasons one color starts to dominate and then it is kind of a runaway reaction, everything changes quickly either to black, or white.

In a way Kenso Sai work implements this.

 

[Mayhem]

This is basically kind of a process I remember being suggested even before their works (I learned about it in the early eighties, and I strongly doubt it was a fresh one then). The idea is that of a self-enforcing change: imagine you have a bag of black and white marbles. You draw three at random. If they are identical - return them. If one is different from two others: change its color and return three identical marbles to the bag. This is an unstable equilibrium - initially nothing happens, but at some point for purely statistical reasons one color starts to dominate and then it is kind of a runaway reaction, everything changes quickly either to black, or white.

In a way Kenso Sai work implements this.

I'm not aware of the scope of Soai's work, i.e. how many instances of the Soai reaction have been discovered, but the molecules studied seem highly specific, especially the presented "tert-butyl alkyne" derivative.

 

[Borek]

but the molecules studied seem highly specific

Yes, and that makes me doubt this is really the answer we are looking for. Still, an interesting system, and definitely proves there is no need for magic nor divine intervention

 

[Mayhem]

Yes, and that makes me doubt this is really the answer we are looking for. Still, an interesting system, and definitely proves there is no need for magic nor divine intervention

No, but certainly a need for an intelligent "creator" in this instance.

 

[pines-demon]

So according to the Nobel document their discovery solves the problem of the helicity of organic molecules on Earth. But have they identified the exact process that occurred on early years of Earth?

 

[Borek]

So according to the Nobel document their discovery solves the problem of the helicity of organic molecules on Earth. But have they identified the exact process that occurred on early years of Earth?

No.

And generally speaking: their discovery doesn't "solve" anything. It proves the solution can exist and can be rooted in a natural process. But none of the examples they found seems "practical" - as in "possible to appear in a typical mix of naturally existing reagents we expect to see in the primordial soup".

 

[Mayhem]

No.

And generally speaking: their discovery doesn't "solve" anything. It proves the solution can exist and can be rooted in a natural process. But none of the examples they found seems "practical" - as in "possible to appear in a typical mix of naturally existing reagents we expect to see in the primordial soup".

I have pondered if heterogenous reactions could be a potential lead for the question.

Soai's work demonstrates how homochirality can be self-amplifying, rendering the single-origin of chiral biomolecules plausible. Since the primordial soup existed in the primordial cauldron of the ancient Earth, I wonder if there existed certain minerals with a surface structure that allowed for stereospecific chemistry. Here I refer to how the active site of enzymes can be stereospecific due to their three-dimensional structure, although these active sites also involve asymmetric biomolecules, which challenges the self-consistency of the idea.

If we assume there exists / was such a mineral with a stereospecific surface structure, it still begs the question of why that surface structure was that orientation. As far as I know, it doesn't matter if biology is left or right handed, as long everything remains consistent. That is, if we inverted the configuration of all molecules everywhere at once, it would be indistinguishable in behavior. This necessitates only an initial, arbitrary bias for symmetry, which seems conceptually plausible in the context of geology ... but I'm out of my depth here.

 

[Borek]

I have pondered if heterogenous reactions could be a potential lead for the question.

Won't give you citations, but I am more than sure I read about the idea years ago - without any conclusions though, just as a speculation.

I started to wonder though: many reactions tend to "keep" chirality of reactants (or to reverse it, depending on the mechanism, but that means they still belong to the same pathway). Technically that could mean initial existence of two separate "kingdoms", L and D, competing for the resources. Once a member of one of the "kingdoms" evolves (at random) to become autotrophic and produce molecules of one type, "kingdom" takes over, as resources of one type become abundant. After that whole system evolves around one chirality, only enforcing its dominance. Pure speculation.

 

[Mayhem]

Won't give you citations, but I am more than sure I read about the idea years ago - without any conclusions though, just as a speculation.

I started to wonder though: many reactions tend to "keep" chirality of reactants (or to reverse it, depending on the mechanism, but that means they still belong to the same pathway). Technically that could mean initial existence of two separate "kingdoms", L and D, competing for the resources. Once a member of one of the "kingdoms" evolves (at random) to become autotrophic and produce molecules of one type, "kingdom" takes over, as resources of one type become abundant. After that whole system evolves around one chirality, only enforcing its dominance. Pure speculation.

The key is finding the initial asymmetry. Maybe something with polarized light. Who knows.

 

[pines-demon]

The key is finding the initial asymmetry. Maybe something with polarized light. Who knows.

Why is key? It could be random, the key seems to find the right natural amplifying mechanism.