Glossary & Sources

Glossary

Asymmetric autocatalysis

A reaction whose chiral product catalyses its own formation, so an excess of one hand reinforces itself.

Chirality

The property of not being superposable on one’s mirror image.

Deracemisation

Converting a racemate into a single enantiomer without discarding half the material.

Distomer

The less active enantiomer of a drug; the eutomer is the more active one.

Enantiomer

One of the two mirror-image forms of a chiral molecule.

Enantiomeric excess (ee)

([R] − [S]) / ([R] + [S]); zero for a racemate, one for a single enantiomer.

Eudismic ratio

The ratio of potencies of the two enantiomers of a drug.

Frank model

The 1953 scheme — autocatalysis plus mutual antagonism — whose racemic state is unstable.

Heterochiral complex

A catalyst species carrying one ligand of each hand; achiral, so its product is racemic.

Hyperpositive NLE

The regime in which a partially resolved ligand outperforms the enantiopure one; not reproduced by the ML₂ model.

Ligand

A molecule bound to a metal centre; in asymmetric catalysis, the source of the handedness.

ML₂ model

Kagan’s treatment of a metal bearing two chiral ligands, giving ee_prod = ee_max · ee_aux · (1+β)/(1+gβ).

Non-linear effect

Any departure of product ee from proportionality with catalyst ee.

Racemate

An equal mixture of the two enantiomers.

Soai reaction

The addition of a dialkylzinc to a pyrimidyl aldehyde; the first and still essentially the only clean asymmetric autocatalysis.

The work the prize names

• Puchot C., Samuel O., Duñach E., Zhao S., Agami C., Kagan H. B. “Nonlinear effects in asymmetric synthesis. Examples in asymmetric oxidations and aldolization reactions.” J. Am. Chem. Soc. 108, 2353 (1986).The first report that product ee need not track catalyst ee.
• Guillaneux D., Zhao S.-H., Samuel O., Rainford D., Kagan H. B. “Nonlinear Effects in Asymmetric Catalysis.” J. Am. Chem. Soc. 116, 9430–9439 (1994). doi:10.1021/ja00100a004The ML and ML₂ models, and the equation derived in Part 2.
• Soai K., Shibata T., Morioka H., Choji K. “Asymmetric autocatalysis and amplification of enantiomeric excess of a chiral molecule.” Nature 378, 767–768 (1995).The reaction that realised Frank's model in a flask.
• Frank F. C. “On spontaneous asymmetric synthesis.” Biochim. Biophys. Acta 11, 459–463 (1953).Two pages, forty-two years early, and the whole of Part 3.

The prize

• Press release, Nobel Prize in Chemistry 2026, NobelPrize.org.
• Henri B. Kagan and Kenso Soai win Nobel Prize in chemistry, NPR, 7 October 2026.

Laureate details are taken from NobelPrize.org: Kagan, born 15 December 1930 in Boulogne-Billancourt, Université Paris-Sud, Orsay; Soai, born 1950 in Hiroshima, Tokyo University of Science. At least one news report on the day conflated their ages.