Chapter 5, Problem 43P

Interpretation Introduction

Interpretation:Stereocenters in the indicated chiral molecules should be marked and any one of the stereoisomers should be drawn along with absolute stereochemistry as R or S.

  

Concept introduction:Chiral carbon is any stereocenter attached to four different alkyl substituents. It is also known as stereocenter. If any two of the substituent happen to be similar the center is regarded as achiral. However, the most essential criteria that help to distinguish a chiral or non-chiral system is presence of any symmetry element. If any plane center or axis of symmetry is identified it makes molecule achiral and optically inactive.

In order to assign absolute configuration of R and S, Cahn − Ingold − Prelog rules are used and the first step is to assign the priority order on the basis of atomic number. The one with highest atomic number gets highest priority and is designated as a and so on with the lowest priority group at the bottom.

If the groups read from highest towards least in clockwise fashion then R is assigned to the stereocenter if the rotation is anticlockwise then S is assigned at the configuration.

The Fischer projection is written along with the priorities assigned and groups are interchanged between adjacent places so as to obtain lowest priority group at the bottom or lowest priority.