Racemic Mixture vs. Meso Compound — What's the Difference?
Edited by Tayyaba Rehman — By Fiza Rafique — Published on December 19, 2023
A racemic mixture contains equal amounts of left and right-handed enantiomers of a chiral molecule, while a meso compound is a molecule with multiple chiral centers but is achiral overall.
Difference Between Racemic Mixture and Meso Compound
Table of Contents
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Key Differences
Racemic mixture pertains to a sample that has an equal proportion of two enantiomers, which are non-superimposable mirror images of each other. These mixtures don't exhibit optical activity since the rotations caused by each enantiomer cancel out. On the contrary, a meso compound, while having multiple chiral centers, doesn't display optical activity because it's internally symmetrical. Its mirror image is superimposable, making it achiral.
The distinction between racemic mixture and meso compound is fundamental in stereochemistry. A racemic mixture is a 50:50 mixture of two enantiomers, with each enantiomer rotating plane-polarized light in opposite directions. Meso compounds, however, despite having chiral centers, are symmetrical and have a plane of symmetry. This causes their optical rotations to cancel out internally.
Racemic mixtures can sometimes be separated into their individual enantiomers through a process called resolution. Meso compounds, in contrast, can't be separated into optically active forms because they are inherently optically inactive. Racemic mixtures are formed when there's no chiral influence during the synthesis of a chiral molecule. Meso compounds arise when a molecule with multiple chiral centers has a superimposable mirror image due to its symmetry.
In summary, while both racemic mixtures and meso compounds are optically inactive, their reasons differ. Racemic mixtures are inactive because of the cancelation effect of equal amounts of enantiomers. Meso compounds are inactive due to internal symmetry despite having chiral centers.
Comparison Chart
Definition
50:50 mixture of two enantiomers
Molecule with multiple chiral centers but achiral
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Optical Activity
Optically inactive due to cancelation effect
Inherently optically inactive
Origin of Inactivity
Equal amounts of enantiomers
Internal symmetry
Separation of Enantiomers
Possible through resolution
Not possible since it's inherently achiral
Chiral Centers
Not always present
Always present but with a plane of symmetry
Compare with Definitions
Racemic Mixture
Racemic mixtures can sometimes be separated into individual enantiomers.
Through resolution, the racemic mixture was separated into its enantiomers.
Meso Compound
Meso compounds' mirror images are superimposable.
The meso compound's mirror image perfectly overlapped with its original structure.
Racemic Mixture
Racemic mixtures don't exhibit optical activity.
Despite being chiral, the racemic mixture didn't rotate plane-polarized light.
Meso Compound
Meso compounds arise from molecular symmetry despite chiral centers.
The compound, although having two chiral centers, was a meso compound due to its symmetry.
Racemic Mixture
A racemic mixture consists of equal amounts of two enantiomers.
The synthesis yielded a racemic mixture of the desired compound.
Meso Compound
Despite having chiral centers, meso compounds are optically inactive.
The molecule, being a meso compound, didn't rotate plane-polarized light.
Racemic Mixture
Racemic mixtures have non-superimposable mirror images present in equal amounts.
The compound's racemic mixture contained both enantiomers in 50:50 ratio.
Meso Compound
Meso compounds possess a plane of symmetry.
The internal symmetry of the meso compound negated its optical activity.
Racemic Mixture
A racemic mixture results when there's no chiral influence in synthesis.
The absence of a chiral catalyst led to the formation of a racemic mixture.
Meso Compound
A meso compound is a molecule with multiple chiral centers but is overall achiral.
Tartaric acid has a meso compound that's optically inactive.
Common Curiosities
Does a meso compound have chiral centers?
Yes, a meso compound has multiple chiral centers but remains achiral overall due to its symmetry.
Can a meso compound rotate plane-polarized light?
No, meso compounds are optically inactive due to their internal symmetry.
Why doesn't a racemic mixture exhibit optical activity?
Because the optical activities of the two enantiomers in a racemic mixture cancel each other out.
Is it possible to separate enantiomers from a racemic mixture?
Yes, racemic mixtures can sometimes be separated into individual enantiomers through resolution.
Are all compounds with multiple chiral centers meso compounds?
No, only those with a plane of symmetry are meso compounds.
Are meso compounds rare in nature?
They're not common but can be found in certain molecules, like some forms of tartaric acid.
What constitutes a racemic mixture?
A racemic mixture contains equal amounts of left and right-handed enantiomers.
How can you transform a racemic mixture into a single enantiomer?
One method is through chiral resolution or using chiral agents in synthesis.
Can a racemic mixture be naturally occurring?
Yes, racemic mixtures can be found both naturally and synthetically produced.
Can a molecule with a single chiral center be a meso compound?
No, meso compounds must have at least two chiral centers.
Is the mirror image of a meso compound another enantiomer?
No, the mirror image of a meso compound is superimposable on the original.
Why is a meso compound achiral despite having chiral centers?
Because its internal symmetry causes its mirror image to be superimposable.
Is it always guaranteed to obtain a racemic mixture during synthesis?
No, it depends on the conditions and presence of chiral influences during synthesis.
Can racemic mixtures be used in pharmaceuticals?
Yes, but often one enantiomer is more therapeutically active than the other.
Why is understanding the difference between racemic mixtures and meso compounds crucial in chemistry?
Because their properties, reactivity, and biological activity can differ, affecting synthesis, drug design, and other applications.
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Fiza RafiqueFiza Rafique is a skilled content writer at AskDifference.com, where she meticulously refines and enhances written pieces. Drawing from her vast editorial expertise, Fiza ensures clarity, accuracy, and precision in every article. Passionate about language, she continually seeks to elevate the quality of content for readers worldwide.
Edited by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
