Wade:Organic ChemistryCh5
Terms
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- detailed steriochemical picture of a molecule; the (R) and (S) configuration at each assymetric carbon atom
- absolute configuration
- not chiral; same as its mirror image
- achiral
- a carbon atom that is bonded to four different groups
-
asymmetric carbon atom or
chiral carbon atom - accepted method for designating the absolute configuration of a chirality center ( usually an asymmetric carbon) as either (R) or (S)
- Cahn-Ingold-Prelog convention
- different from its mirror image
- chiral
- the IUPAC term for an atom holding a set of ligands in a spatial arrangement that is not superimposable on its mirror image
- chirality center
- a molecule or object that is chiral and can use its own chiralityto differentiate between mirror images
- chiral probe
- on the same side of a ring or double bond
- cis
- isomers that differ in their geometric arrangement on a ring or double bond; subclass of diastereomers
- cis-trans isomers
- the two possible spatial arrangements around a chirality center or other stereocenter
- configuration
- structures that differ only by rotations about single bonds; interconvert at room temperature and are not true isomers
-
conformers or
conformations - isomers that differ in the order that their atoms are bonded
- constitutional isomers
- rotating the plane of polarized light clockwise (+) or (d)
- dextrorotatory
- stereoisomers that are not mirror images
- diastereomers
- the excess of one enantiomer in a mixture of enantiomers expressed as a percentage of the mixture; similar to optical purity
- enantiomeric excess (e.e.)
- a pair of non-superimposable mirror-image molecules; mirror-image isomers
- enantiomers
- a method of drawing an asymmetric carbon atom as a cross; carbon chain is kept along the vertical; horizontal bonds project toward the viewer
- Fischer projections
-
a plane of symmetry through the middle of a molecule, dividing the molecule into two mirror-image halves
* a molecule with an internal mirror plane of symmetry cannot be chiral - internal mirror plane
- different compounds with the same molecular formula
- isomers
- rotating the plane of polarized light counterclockwise (-) or (l)
- levoratatory
- compounds with identical properties except for the direction in which they rotate polarized light
- optical isomers
- capable of rotating the plane of polarized light
- optically active
- the specific rotation of a mixture of two enatiomers, expressed as a percentage of the specific rotation of one of the pure enantiomers
- optical purity (o.p.)
- light composed of waves that vibrate in only one plane
- plane-polarized light
- an instrument that measures the rotation of plane-polarized light by an optically active compound
- polarimeter
- mixture of equal quantities of enantiomers, such that the mixture is optically inactive
- racemic mixture
- experimentally determined relationship between the configurations of two molecules even when absolute configurations are not known
- relative configuration
- process of separating a racemic mixture into the pure enantiomers
- resolution
- a chiral compound used for separating enantiomers
- resolving agent
- measure of a compounds ability to rotate the plane of polarized light...
- specific rotation
- atom that gives rise to stereoisomers when its groups are interchanged; asymmetric carbon atoms and double-bonded carbons in cis-trans alkenes are the most common
- stereocenter
- study of the three-dimensional structure of molecules
- stereochemistry
- isomers whose atoms are bonded togather in the same order, but they differ in how the atoms are oriented in space
- stereoisomer
- isomers that differ in the order in which their atoms are bonded togather
- structural isomers
- identical in all respects; three-dimensional positions of all atoms coincide when the molecules are placed on top of each other
- superimposable
- opposite sides of a ring or double bond
- trans