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Isomer: Difference between revisions
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[[File:File_Chirality_with_hands.png|thumb|right|Two enantiomers of a generic amino acid that is chiral.]] | [[File:File_Chirality_with_hands.png|thumb|right|Two enantiomers of a generic amino acid that is chiral.]] | ||
An enantiomer is one of two stereoisomers that are mirror images of each other that are non-superimposable (not identical). The model used to convey the idea of isomers being non-superimposable is a person's hands. One's left and right hands are the same except for opposite orientation. Organic compounds that contain a chiral carbon usually have two non-superimposable structures. A chiral carbon is a carbon attached to four completely different functional groups. The enantiomers will have a "left-hand" and a "right-hand" molecule. This property is used in naming the isomers: the "right-hand" is given the prefix (R), and the "left-hand" is given the prefix (S). Enantiomers rotate in plane-polarized light, and this property is also used in naming the enantiomers as either clockwise (prefix of dextro- or +) or anti-clockwise (prefix of levo or -). | An enantiomer is one of two stereoisomers that are mirror images of each other that are non-superimposable (not identical). The model used to convey the idea of isomers being non-superimposable is a person's hands. One's left and right hands are the same except for opposite orientation. Organic compounds that contain a chiral carbon usually have two non-superimposable structures. A chiral carbon is a carbon attached to four completely different functional groups. The enantiomers will have a "left-hand" and a "right-hand" molecule. This property is used in naming the isomers: the "right-hand" is given the prefix (R), and the "left-hand" is given the prefix (S). Enantiomers rotate in plane-polarized light, and this property is also used in naming the enantiomers as either clockwise (prefix of dextro- or +) or anti-clockwise (prefix of levo or -). | ||
===Nomenclature=== | |||
Often, the <small>D</small>/<small>L</small> system (with small caps) and the <small>d</small>/<small>l</small> system (with lower-case) are confused. The result is that the levorotary <small>l</small>-ephedrine is wrongly named <small>L</small>-ephedrine and the dextrorotary <small>d</small>-pseudoephedrine (the diastereomer) wrongly <small>D</small>-pseudoephedrine. | |||
== Chirality == | == Chirality == | ||
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A racemate is optically inactive, meaning that there is no net rotation of plane-polarized light. Although the two enantiomers rotate plane-polarized light in opposite directions, the rotations cancel because they are present in equal amounts. | A racemate is optically inactive, meaning that there is no net rotation of plane-polarized light. Although the two enantiomers rotate plane-polarized light in opposite directions, the rotations cancel because they are present in equal amounts. | ||
In contrast to the two pure enantiomers, which have identical physical properties except for the direction of rotation of plane-polarized light, a racemate sometimes has different properties from either of the pure enantiomers. Different melting points are most common, but different solubilities and boiling points are also possible.<ref>https://en.wikipedia.org/wiki/Racemic_mixture | Racemic mixture | In contrast to the two pure enantiomers, which have identical physical properties except for the direction of rotation of plane-polarized light, a racemate sometimes has different properties from either of the pure enantiomers. Different melting points are most common, but different solubilities and boiling points are also possible.<ref>https://en.wikipedia.org/wiki/Racemic_mixture | Racemic mixture (Wikipedia)</ref> | ||
Pharmaceuticals may be available as a racemate or as the pure enantiomer (enantiopure), which might have different potencies and effects. Because biological systems have many chiral asymmetries, pure enantiomers frequently have very different biological effects. Examples include glucose and [[methamphetamine]].<ref>https://en.wikipedia.org/wiki/Racemic_mixture | Racemic mixture | Pharmaceuticals may be available as a racemate or as the pure enantiomer (enantiopure), which might have different potencies and effects. Because biological systems have many chiral asymmetries, pure enantiomers frequently have very different biological effects. Examples include glucose and [[methamphetamine]].<ref>https://en.wikipedia.org/wiki/Racemic_mixture | Racemic mixture (Wikipedia)</ref> | ||
== Enantiopure == | == Enantiopure == | ||
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==References== | ==References== | ||
{{reflist|2}} | {{reflist|2}} | ||
[[Category:Chemistry]] | |||
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