Optical Isomers
Definition and meaning of Optical Isomers in chemistry.
Optical isomers are compounds with identical molecular formulas that are non-superimposable mirror images of each other and rotate plane-polarized light in opposite directions.
In more detail
These isomers arise when a molecule contains a chiral center, most commonly a carbon atom bonded to four different groups. The two forms are called enantiomers, and they rotate the plane of polarized light in opposite directions: one dextrorotatory (rotating clockwise, +) and one levorotatory (rotating counterclockwise, -). Despite these different optical properties, enantiomers have identical physical and chemical properties in non-chiral environments. However, they often behave differently in biological systems where chiral receptors or enzymes are involved.
Key facts
| Structural basis | Non-superimposable mirror images |
|---|---|
| Optical rotation | (+) dextrorotatory and (-) levorotatory |
| Example compound | C3H6O3 (lactic acid) |
| Field | Organic Chemistry |
Lactic acid (C3H6O3) exists as two optical isomers, or enantiomers. One form rotates plane-polarized light clockwise (dextrorotatory, +), while the other rotates it counterclockwise (levorotatory, -). Despite these opposite optical properties, both isomers have identical melting points, boiling points, and solubility in water.
Frequently asked questions
What causes optical isomerism?
A chiral center, usually a carbon atom bonded to four different groups, produces two non-superimposable arrangements that rotate plane-polarized light in opposite directions.
Do optical isomers have the same properties?
In non-chiral environments, yes: they have identical melting and boiling points. However, they rotate light in opposite directions and may react differently in chiral biological environments like enzymes or receptors.