Isomer: Difference between revisions

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====Diastereomers====

Diastereomerism occurs when two or more stereoisomers of a compound have different configurations at one or more (but not all) of the equivalent stereocenters and are not mirror images (enantiomers) of each other. When two diastereoisomers differ from each other at only one stereocenter they are epimers. Each stereocenter gives rise to two different configurations and thus increases the number of stereoisomers by a factor of two.

"Cis–trans isomers" are used to describe any molecules with restricted rotation in the molecule. However, these descriptors only describe relative stereochemistry based on group bulkiness or principal carbon chain, so can be ambiguous. This is especially problematic for double bonds that have more than two substituents.

"Cis–trans isomers" are used to describe any molecules with restricted rotation in the molecule. However, these descriptors only describe relative stereochemistry based on group bulkiness or principal carbon chain, so it can be ambiguous. This is especially problematic for double bonds that have more than two substituents.

E/Z isomers, which have restricted rotation within the molecule, specifically isomers containing a double bond, are configurational isomers. For alkenes with more than two substituents E-Z notation is used instead of cis and trans. If possible, E and Z is also preferred in compounds with two substituents.

====Enantiomers====

[[File:Enantiomer.png|298px|thumb|right|Example of enantiomerism in lactic acid, showing left-hand and right-hand sides.]]

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 ====Diastereomers====
 Diastereomerism occurs when two or more stereoisomers of a compound have different configurations at one or more (but not all) of the equivalent stereocenters and are not mirror images (enantiomers) of each other. When two diastereoisomers differ from each other at only one stereocenter they are epimers. Each stereocenter gives rise to two different configurations and thus increases the number of stereoisomers by a factor of two.
-"Cis–trans isomers" are used to describe any molecules with restricted rotation in the molecule. However, these descriptors only describe relative stereochemistry based on group bulkiness or principal carbon chain, so can be ambiguous. This is especially problematic for double bonds that have more than two substituents.
+"Cis–trans isomers" are used to describe any molecules with restricted rotation in the molecule. However, these descriptors only describe relative stereochemistry based on group bulkiness or principal carbon chain, so it can be ambiguous. This is especially problematic for double bonds that have more than two substituents.
 E/Z isomers, which have restricted rotation within the molecule, specifically isomers containing a double bond, are configurational isomers. For alkenes with more than two substituents E-Z notation is used instead of cis and trans. If possible, E and Z is also preferred in compounds with two substituents.
 ====Enantiomers====
 [[File:Enantiomer.png|298px|thumb|right|Example of enantiomerism in lactic acid, showing left-hand and right-hand sides.]]