In chemistry two stereoisomers are said to be enantiomers if one can be superimposed on the mirror image of the other. Enantiomers are mirror images of one another much as a right hand is the mirror image of a left hand.-1... Stereoisomerism is the arrangement of atoms in molecules whose connectivity remains the same but their arrangement in space is different in each isomer. ...
Enantiomers rotate planepolarized light by equal amounts but in opposite directions. A solution of equal parts of an optically active isomer and its enantiomer is known as a racemic solution and has a net rotation of plane polarized light of zero. A more in-depth explanation of this is in the footnotes for optical isomerism. In mathematics, a plane is the fundamental two-dimensional object. ... This article treats polarization in electrodynamics. ... In chemistry, a racemate is a mixture of equal amounts of left- and right-handed stereoisomers of a chiral molecules. ... Optical isomerism is a form of isomerism (specifically stereoisomerism) whereby the different 2 isomers are the same in every way except being non-superimposable mirror images1 of each other. ...
Enantiomers will have the opposite prefixes of each other:
D- becomes L-
dextro becomes levo
(+)- becomes (-)-
R- becomes S-
Stereo chemistry of enantiomers is of great importance nowadays. Food and Drug Administration (FDA) of the United States of America, recently recommended that drug molecules having stereocentres should be given to the patients only in the active enantiomeric form and not as a racemic mixture.
Definitions:
Any non-racemic chiral substance is called scalemic
A chiral substance is enantiopure or homochiral when only one of two possible enantiomers is present.
A chiral substance is enantioenriched or heterochiral when an excess of one enantiomer is present but not to the exclusion of the other.
enantiomeric excess or ee is a measure for how much of one enantiomer is present compared to the other. For example in a sample with 40% ee in R, the remaining 60% is racemic with 30% of R and 30% of S so that the total amount of R is 70%.
External link
Course notes (http://www.chem.umd.edu/courses/chem233mazz/chapternotes/chapter9notes.pdf) for a lecturer's introduction to stereochemistry and enantiomers.
infelicitous stereochemical nomenclatures (http://www.uottawa.ca/publications/interscientia/inter.4/eliel/eliel.html) for stereochemical nomenclature
The present study focuses on determining whether the enantioselective esterification reaction of flurbiprofen with n-butanol, as shown for Candida rugosa lipase in Figure 1, can be improved by using hydrophobic solvents, varying the water activity, and using lipases from different sources.
In conclusion, the results of this study suggest that the enantioselective esterification of flurbiprofen catalyzed by lipases is significantly influenced by the nature of the solvent, the source of the lipase, and the activity of water in the reaction medium.
Tsai, S.W. and Wei, H.J. Enantioselective esterification of racemic naproxen in organic solvent.
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