What are Mesomers?? Can we apply CIP nomenclature to Mesomers to make R nd S configurations???

1 Answer
Jan 23, 2018

Here's what I get.

Explanation:

Mesomer is just another term for a meso compound·

A meso compound is a type of stereoisomer that has two or more chiral centres but is optically inactive because it has an internal plane of symmetry.

cis-1,2-Dichlorocyclohexane is a meso compound.

MesoMeso

The two mirror images are superimposable on each other and each molecule is divided into two mirror-image halves by the horizontal red lines.

We can use the Cahn-Ingold-Prelog system to name these structures.

The left-hand structure would be named (1R,2S)-1,2 dichlorocyclohexane, while the other would be named (1S,2R)-1,2 dichlorocyclohexane.

However, they are the same compound, so there is only correct IUPAC name. It is based on the arbitrary assumption that the prefix first cited is R.

Thus, both structures are named (1R,2S)-1,2 dichlorocyclohexane.