Organic Chemistry

Structures and Nomenclature

How and when was molecular chirality discovered?

Nonracemic mixtures rotate the plane of a beam of polarized light in either a clockwise or counterclockwise direction. Jean-Baptiste Biot, a French physicist, observed this effect in 1815 with quartz crystals, turpentine, and sugar solutions. These were important results in understanding the nature of light, but it was Louis Pasteur in 1848 that figured out that the effect was based on molecular properties. Pasteur painstakingly separated enantiomerically pure crystals from a racemic mixture of tartaric acid and showed that the two enantiomers rotated light in opposite directions.


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