Assign an R or S configuration to the chiral center in each molecule

Key concept

Enantiomers

Enantiomers are a type of stereoisomers, which are isomers that have the same chemical formula and the same connectivity of atoms, but a different arrangement of atoms in space.

Enantiomers are a specific type of stereoisomers that are mirror images of each other, but are non-superimposable. They are also known as optical isomers, because they rotate plane polarized light in opposite directions.

Enantiomers are also chemically identical and have the same physical properties such as melting and boiling point, solubility, but they differ in their biological activity and reactivity towards other chiral molecules. For example, one enantiomer of a drug may have the desired therapeutic effect, while the other enantiomer may have no effect or even harmful side effects.

Enantiomers are represented by the (R) and (S) notation, which is based on the priority of the substituents attached to the chiral center.

R is when the order of priority is clockwise, and  is when the order of priority is counterclockwise.

Then it is necessary to name which enantiomer is  and which is .

1) Assign priority ranking around the chiral center for each substituent.

2) We  must put the lowest ranking 4, pointing away from you. Often seen as a dashed line.

3) Then if the remaining 1,2 , and 3 molecules beginning with 1 are clockwise then this enantiomer is labeled  if they are counterclockwise it is labeled S.

If we leave the 4 ranking in the non-pointing away position, then the answer will simply be the opposite. R will be S and vice versa.

Step 1 of 4

We have to assign R and S configuration for each of the molecule