Just as our hands are mirror images of each other, molecules can also have mirror images that can not be superimposed on them. These molecules are called enantiomers.
An example of this enantiomer is sedative thalidomide, which was sold in various countries around the world between 1957 and 1961. It was withdrawn from the market when it was discovered that it caused birth defects. An enantiomer determined the desired sedative effects, while the other, inevitably present in equal amounts, caused birth defects.
The mecoprop herbicide is a racemic mixture with the enantiomer (R) – (+) (“Mecoprop-P”, “Duplosan KV”) with herbicidal activity.
Another example is the antidepressants escitalopram and citalopram. Citalopram is a racemic mixture (1: 1 of (S) -citalopram and (R) -citalopram); escitalopram [(S) -citalopram] is a pure enantiomer. The dose for escitalopram is typically 1/2 of those for citalopram.
What is an example of an enantiomer?
An example of an enantiomer is the molecule known as lactic acid. Lactic acid exists in two enantiomeric forms, which are mirror images of each other. These forms are called L-lactic acid and D-lactic acid. The L and D prefixes refer to the configuration of the molecule’s chiral carbon, which is the carbon atom that is bonded to four different groups.
Lactic acid is produced in the body during anaerobic respiration and is responsible for the muscle soreness experienced after intense exercise. The L and D forms of lactic acid have different biological properties. For instance, L-lactic acid is the predominant form found in human muscles, while D-lactic acid can accumulate in certain medical conditions such as bacterial overgrowth in the intestines.
The enantiomers of lactic acid have identical physical and chemical properties, except for their interaction with polarized light. They rotate the plane of polarized light in opposite directions, with L-lactic acid rotating it to the left (levorotatory) and D-lactic acid rotating it to the right (dextrorotatory).
What is an enantiomer?
An enantiomer refers to one of the two mirror-image forms of a chiral molecule. Chirality arises when a molecule contains a carbon atom that is bonded to four different groups. Enantiomers have the same chemical formula and connectivity, but they differ in their three-dimensional arrangement, similar to how our left and right hands are mirror images of each other. Due to their structural differences, enantiomers often exhibit distinct biological, physical, and chemical properties.
What are the two enantiomers?
The two enantiomers of a chiral molecule are referred to as the R and S enantiomers or the (+) and (-) enantiomers. These labels are assigned based on a set of rules known as the Cahn-Ingold-Prelog (CIP) system. The R and S nomenclature determines the absolute configuration of the molecule’s chiral center, with R denoting “rectus” (Latin for right) and S denoting “sinister” (Latin for left). These designations allow for a consistent and standardized way to describe the spatial arrangement of the molecule’s substituents.