Question

how we could distingyish between enantiomer, diastereoisomer and identic molecule?

Answer 1

There can be several structural formulas for a single molecular formula. These are known as isomers. Isomers can be defined as “different compounds that have the same molecular formula.” There are mainly two types of isomers called constitutional isomers and stereoisomers. For example, C4H10 can have following constitutional isomers.

Constitutional isomers are “isomers that differ because their atoms are connected in a different order.” Stereoisomers are isomers that differ from the spatial arrangement of the atoms. Diastereomers and enantiomers are the two types of stereoisomers.

Diastereomers

Diastereomers are stereoisomers whose molecules are not mirror images of each other. For example, cis and trans isomers are Diastereomers.

Enantiomers

Enantiomers are “stereoisomers whose molecules are nonsuperposable mirror images of each other. “ Enantiomers are only possible with molecules, which are chiral. Chiral molecule is the one that is not identical with its mirror image. For a molecule to be chiral, it should have one tetrahedral atom with four different groups attached to it. This carbon atom is known as a stereocenter. Chiral molecules make mirror images that are not superposable. So the molecule and the mirror image are said to be enantiomers.

– Diastereomers of a molecule are not mirror images of each other, but enantiomers are mirror images.

– Molecules with more than one stereocenter can be Diastereomers if they are not mirror images of each other. If there is only one stereo center, then that molecule has enantiomers.

– Diastereomers have different physical and chemical properties. But enantiomers have similar physical and chemical properties except, they have different optical properties towards the plane polarized light.

The molecules have the same chemical formula so they might be isomers. The sequence of atom attachments is identical so they are not constitutional isomers. They cannot be interconverted by rotation around one or more single bonds, so they are stereoisomers