Isomerism: Concept where molecules have the same molecular formula but different structures or orientations.
Structural Isomers: Molecules with the same molecular formula but different connectivity.
Example: Straight-chain butane vs. isobutane (C4H10).
Stereoisomers
Definition: Compounds with the same molecular formula and connectivity, differing in 3D orientation.
Types:
Enantiomers
Diastereomers
Enantiomers
Definition: Molecules that are non-superposable mirror images.
Analogous to left and right hands as non-superposable mirror images.
Example: A molecule reflected across a mirror plane may not overlap properly with the original.
Characteristics of Enantiomers
Chirality: Quality of having non-superposable mirror image.
Chiral Center: A carbon with four different substituents.
Example:
A carbon with bromine, hydrogen, and two different carbon chains is chiral.
A carbon with bromine, hydrogen, and two identical methyl groups is not chiral.
Achiral Molecules: Molecules with superposable mirror images.
Example:
A molecule with two identical fluorine atoms.
Achiral due to identical substituents or ability to superpose mirror images.
Conclusions
Chiral vs. Achiral: Understanding stereoisomerism helps identify if a molecule has a non-superposable mirror image (chiral) or a superposable one (achiral).
Additional Information
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