| Enantiomer |
Articles about Enantiomer |
Information AboutEnantiomer |
| CATEGORIES ABOUT ENANTIOMER | |
| stereochemistry | |
|
Enantiomers have - when present in a symmetric environment - identical chemical and physical properties except for their ability to rotate Plane - Polarized 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. NAMING CONVENTIONS ''main article:'' Optical Isomerism There are several conventions used for naming Chiral compounds, all displayed as a prefix before the chemical name of the substance:
- based on the substance's ability to rotate polarized light.
- based on the actual geometry of each enantiomer, with the version synthesized from naturally occurring glyceraldehyde being considered the D- form.
The (+)- vs. (−)- convention is The other two conventions are based on the actual geometry of each enantiomer. In nature, many chiral substances are only produced in one optical form, while (most) man-made chiral substances are racemic mixtures. the purity of enantiomers can be determined by Optical Rotation . MORE DEFINITIONS
ENANTIOPURE PREPARATIONS Several strategies exist for the preparation of enantiopure compounds. This first method is the separation of a racemic mixture into its isomers. Louis Pasteur in his pioneering work was able to isolate the isomers of Tartaric Acid because they crystallize from solution as crystals each with a different symmetry. A less common method is by Enantiomer Self-disproportionation In a non-symmetric environment such as a biological environment, enantiomers may react at different speeds with other substances. This is the basis for Chiral Synthesis . ENANTIOPURE MEDICATIONS Advances in industrial chemical processes have allowed pharmaceutical manufacturers to take drugs that were originally marketed in racemic form and divide them into individual enantiomers, each of which may have unique properties. For some drugs, such as Zopiclone , only one enantiomer ( Eszopiclone ) is active; the FDA has allowed such once-generic drugs to be patented and marketed under another name. In other cases, such as Ibuprofen , both enantiomers produce the same effects. Examples of racemic mixtures and enantiomers that have been marketed include:
Thalidomide is an example of a racemic drug, in which one enantiomer produces a desirable Antiemetic effect, whereas the other is toxic and produces a Teratogenic side-effect. However, the enantiomers are converted into each other in vivo, so chemical processes may not be used to mitigate its toxicity. EXTERNAL LINKS
SEE ALSO |
|
|