What is the Difference Between Achiral and Meso?
🆚 Go to Comparative Table 🆚The terms "achiral" and "meso" refer to the symmetry properties of molecules, specifically those containing chiral centers. Here are the key differences between the two:
- Achiral: An achiral compound is one that can be superimposed on its mirror image. In other words, it is optically inactive, meaning it does not have a specific direction of rotation when it comes to the polarization of light. Achiral compounds can have chiral centers, but they are cancelled out by an internal plane of symmetry.
- Meso: A meso compound is a specific type of achiral compound that has multiple chiral centers. To be a meso compound, it must have an internal symmetry plane that divides the compound in half, reflecting each other by the internal mirror. The key characteristic of a meso compound is that the stereochemistry of the reflected stereocenters should "cancel out". When the optical activity of a meso compound is measured with a polarimeter, it will not show a specific direction of rotation of the polarized light, neither levorotatory (-) nor dexorotatory (+).
In summary, a meso compound is a specific type of achiral compound that has multiple chiral centers, while an achiral compound is a molecule that can be superimposed on its mirror image. All meso compounds are achiral, but not all achiral compounds are meso.
Comparative Table: Achiral vs Meso
The main difference between achiral and meso compounds lies in the presence of chiral centers. Here is a table summarizing the differences between achiral and meso compounds:
Property | Achiral Compounds | Meso Compounds |
---|---|---|
Definition | Achiral compounds are those that can be superimposed on their mirror images, meaning they have no chiral centers. | Meso compounds are achiral compounds that have chiral centers but also have an internal plane of symmetry, making them superimposable on their mirror images. |
Chiral Centers | Achiral compounds have no chiral centers. | Meso compounds have chiral centers, but due to their internal plane of symmetry, they are considered achiral. |
Internal Plane of Symmetry | Achiral compounds have an internal plane of symmetry. | Meso compounds also have an internal plane of symmetry, which makes them superimposable on their mirror images. |
Optical Activity | Both achiral and meso compounds are optically inactive. | Both achiral and meso compounds are optically inactive. |
In summary, achiral compounds have no chiral centers, while meso compounds have chiral centers but an internal plane of symmetry that makes them superimposable on their mirror images. Both achiral and meso compounds are optically inactive.
- Chiral vs Achiral
- Diastereomers vs Enantiomers
- Prochirality vs Prostereoisomerism
- Anomeric Carbon vs Chiral Carbon
- Inductive Effect vs Mesomeric Effect
- Baryons vs Mesons
- Chirality vs Helicity
- Resonance vs Mesomeric Effect
- Enantiotopic vs Diastereotopic
- Muons vs Mesons
- Aliphatic vs Aromatic Amino Acids
- Mesoderm vs Mesenchyme
- Isoschizomers vs Neoschizomers
- Aromatic vs Aliphatic Aldehydes
- Aliphatic vs Aromatic Amines
- Tautomerism vs Metamerism
- Acetal vs Hemiacetal
- Position Isomerism vs Metamerism
- Mesenchyme vs Ectomesenchyme