Chapter 5, Problem 31PP

Interpretation Introduction

Interpretation: The configuration and chirality should be identified for the given molecule by using its structure.

Concept Introduction:

Chiral carbon: Chiral atom is the one which is bonded to four different molecules or groups.

Configuration of a molecule: The configurations of a molecule arise due to the spatial arrangement of atoms. The configuration can be assigned by following CIP rules as follows.

Rules

Find the chiral carbon atom in a molecule.

Assign numbering to the groups bonded to the chiral carbon based on the molecular weight and electronegativity.

If the sequence of the numbering follows clockwise direction the chiral atom is assigned as R configuration.

If the sequence of the numbering follows anticlockwise direction the chiral atom is assigned as S configuration

The R and S configuration of a molecule can be interchanged when a least prior group present in above plane.

To find: The chiral atoms present of the given molecule.

Answer to Problem 31PP

The R and S nomenclature for the given molecule are shown below.

     

Explanation of Solution

• Draw the structure of the given molecule and find the chiral centers.

Chiral centers of the molecule are indicated by using *

The chiral center in the given molecule is marked using*. The * Carbons are chiral since all the carbons are ${\text{sp}}^{\text{3}}$ hybridized and it is bonded to four different groups namely ${\text{OH,CH}}_{\text{3}}{\text{,CH}}_{\text{2}}\text{and}\text{H}\text{.}$ The chirality structure for the given molecule is drawn by which different groups linked to the same central carbon atoms. (For example one –OH group were attached in axial position carbon atoms).

The presence of an asymmetric carbon center is one of several structural features that induce chirality in organic molecules.

• Assign absolute configuration R-S for the given molecules using CIP rules.

 

Chiral carbons are labeled as shown above molecules. Further the right and left hand nomenclature is used to name the enantiomers of chiral compounds. The stereocenter are indicated as R or S.

From the priority is assigned of the above molecules, according to the substitution of elements with higher atomic number, or other attached groups.

Conclusion

For the given organic molecule the chiral centers and absolute configuration is identified by analyzing by R-S sequence rules.