What are Epimers?
In the field of stereochemistry, the term Epimer explicitly states one of a pair of stereoisomers. As per the stereogenic center, the two isomers present in the molecules differ from each other while the remaining remains identical. The Epimers of glucose involve some formations, some examples are starch, glycogen, glucose, polysaccharides, and oligosaccharides.
The stereoisomers β-D-mannopyranose and β-D-glucopyranose are known as epimers because they differ only in the C-2 position of stereochemistry. The hydroxyl group in the β-D-glucopyranose molecule is equatorial (in the "plane" of the ring), whereas, in the β-D-mannopyranose molecule, the C-2 hydroxyl group is axial (up from the "plane" of the ring). These two molecules are known as epimers, but because they do not mirror images of each other, they are not enantiomers.
Enantiomers and Diastereomers
The Enantiomers are also known as Optical isomers, which are two isomers that are relevant to each other by reflection. Let us take a look at the definition of enantiomers and their examples. Enantiomers are non – superimposable and consist of similar physical properties that are expected in a manner they interact with various optical isomers and are related to the other compounds. Hence the different optical isomers can have variant biological effects. The Sedative thalidomide is a very good example of enantiomers.
Diastereomers are also called diastereoisomers, they are a type of stereoisomer. They have been defined as the non-mirror image non-identical stereoisomers. Hence, they are produced when two or more compound stereoisomers have different configurations at either one or more (but not all) of the equivalent or related stereocenters, and they do not mirror images of each other. In case two of the diastereomers differ from each other at only one stereocenter, they are known as epimers. Each of the stereocenters gives rise to two different configurations and thereby increases the stereoisomer's count by a factor of two. The Diastereomers can vary from the enantiomers in the sense that the latter are stereoisomers pairs that differ in all stereocenters, and therefore they are the exact mirror images of one another. An example of a Diastereomer is Dextro Tartaric Acid.
FAQs on Epimers
1. What are epimers, explain with an example?
Monosaccharides such as glucose, fructose, galactose, and mannose are capable of exhibiting different isomerism. As you know, fructose and glucose are the functional isomers of each other as glucose contains the aldehyde group, whereas fructose contains a ketonic group in their molecules. They can also show stereoisomerism because of the presence of chiral carbon atoms. The stereoisomers which are different in their configuration at only one chiral carbon atom are known as Epimers. For example, galactose and glucose are Epimers of each other because they differ only in the position of the hydroxyl group at the C4(chiral carbon atom).
2. Explain what Anomers, and Epimers?
Epimer is known as a stereoisomer where the configuration of the molecule is different at any one of the stereogenic centers in a carbohydrate molecule. All the other stereocenters in the molecules are in the same configuration. The Anomer is also an epimer where the configuration is different only at the hemiacetal/ketal/acetal carbon in the cyclic form. The cyclic form is required as the difference in configuration does not arise if the carbonyl group (aldehyde/ketone) does not form the hemiacetal or acetal. So, the Epimers or anomers are also diastereoisomers.
3. Give the working example of an enantiomer?
Several materials are utilized as enantiomers and have vast use in medicine. One of the examples is the Sedative thalidomide, which was sold around the globe in several countries from the years 1957 to 1961 but it was found to cause birth defects and was withdrawn from the market. One of the enantiomers caused the desirable sedative effects, while the other caused birth defects, presenting equal results which were unavoidable. The two enantiomeric forms are represented by R and S.
4. What are the applications of Diastereomers?
As we have already discussed, the two diastereomers will not have identical chemical properties because of a difference in the configuration of the atoms. This knowledge is harnessed through chiral synthesis to separate the enantiomers mixture. This is the fundamental principle behind chiral resolution. They can be separated by chromatography or recrystallization after preparing the diastereomers.
5. How important are Epimers from the perspective of Organic Chemistry?
The curriculum for the Engineering entrance examinations and the Medical entrance examinations consist of Chemistry as students need to have an idea about the functioning of the chemical materials. Chemistry is divided into three parts which are physical, organic, and inorganic. In the Organic Chemistry portion, stress is given to carbon molecules and their synthesis. One of the most important concepts of organic chemistry is stereochemistry which revolves around the chiral nature of molecules and for students to get a good grasp on this subject, they must have good knowledge about the working of Epimers, their synthesis, and their applications.