Search results
Results from the WOW.Com Content Network
In chemistry, an enantiomer (/ɪˈnænti.əmər, ɛ-, -oʊ-/ [1] ih-NAN-tee-ə-mər), also known as an optical isomer, [2] antipode, [3] or optical antipode, [4] is one of a pair of molecular entities which are mirror images of each other and non-superposable. Enantiomer molecules are like right and left hands: one cannot be superposed onto the ...
A chiral substance is enantioenriched or heterochiral when its enantiomeric ratio is greater than 50:50 but less than 100:0. [23] Enantiomeric excess or e.e. is the difference between how much of one enantiomer is present compared to the other. For example, a sample with 40% e.e. of R contains 70% R and 30% S (70% − 30% = 40%). [24]
Also, for artificial compounds, including medicines, in case of chiral drugs, the two enantiomers sometimes show remarkable difference in effect of their biological actions. [29] Darvon (dextropropoxyphene) is a painkiller, whereas its enantiomer, Novrad (levopropoxyphene) is an anti-cough agent.
Chemical compounds that come as mirror-image pairs are referred to by chemists as chiral or handed molecules. [1] Each twin is called an enantiomer. Drugs that exhibit handedness are referred to as chiral drugs. Chiral drugs that are equimolar (1:1) mixture of enantiomers are called racemic drugs
As a result, different enantiomers of a compound may have substantially different biological effects. Pure enantiomers also exhibit the phenomenon of optical activity and can be separated only with the use of a chiral agent. In nature, only one enantiomer of most chiral biological compounds, such as amino acids (except glycine, which is achiral ...
In 1848, Louis Pasteur became the first scientist to discover chirality and enantiomers while he was working with tartaric acid. During the experiments, he noticed that there were two crystal structures produced but these structures looked to be non-superimposable mirror images of each other; this observation of isomers that were non-superimposable mirror images became known as enantiomers.
That is, on reflecting the meso compound through a mirror plane perpendicular to the screen, the same stereochemistry is obtained; this is not the case for the non-meso tartaric acid, [3] which generates the other enantiomer. The meso compound must not be confused with a 50:50 racemic mixture of the two optically-active compounds, although ...
If molecules have a greater affinity for the opposite enantiomer than for the same enantiomer, the substance forms a single crystalline phase in which the two enantiomers are present in an ordered 1:1 ratio in the elementary cell. Adding a small amount of one enantiomer to the racemic compound decreases the melting point.