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Discuss the optical activity of lactic acid. |
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Answer» Solution :Optical activity of lactic acid : In lactic acid molecule there is an asymmetric chiral carbon atom with four different groups which lead to spatial configurations (d-lactic acid and l-lactic acid) which are super imposable mirror IMAGES of each other. `H-underset("* Chiral Carbon atom")underset(""CH_(3))underset(|)overset(""COOH)overset(|**)(C)-OH` The structures of two ENANTIOMERS of lactic acid are as follows :  When a plane polarized light is passed through a lactic acid solution, the plane of polarized light gets ratated through a certain ANGLE. This property of ROTATING the plane of polarized light towards right rotating the plane of polarized light towards right (clockwase) or towards (left) (anticlockwise) is called optical activity. d-lactic acid rotates the plane of polarized light towards right whereas l-lactic acid rotates the plane of polarized light towards left, which can be DETECTED by polarimeter. In above structures, structure (I) is representing the (+) isomeric from or dextro rotatory from of lactic acid, while structure (II) is representing (-) isomeric from or leavo rotatory from of lactic acid. |
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