Example of optical Isomer : Tartaric acid

Optical Isomers of Tartaric acid (HOOC-CHOH-CHOH-COOH)


Two chiral carbon atoms are present in tartaric acid. The difference in spatial arrangements of various groups in tartaric acid results in d-tartaric acid, l-tartaric acid and an active form known as meso form. In addition to these, racemic modification, another inactive form also exist.

Dextro tartaric acid rotates the plane of polarization of light to right. The rotation due to upper half is strengthened by the rotation of lower half. Laevo tartaric acid is a mirror image of d-form, which rotate the palne of polarization to left.

Racemic tartaric acid is an equimolar mixture of d and l -isomers. It is optically inactive due to external compensation, it can be resolved into d and l forms.

Meso tartaric acid is an inactive variety and the rotation of upper half is compensated by the rotation due to lower half. It cannot be resolved into active constituents. It is therefore inactive due to internal compensation. Mesotartaric acid possess a plane of symmetry.


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