Chapter 21, Problem 73A

Interpretation Introduction

Interpretation:

The optical isomer from the following should be identified:

Concept introduction:

Two mirror image representations are possible for a molecule having chiral center in its structure. If the mirror images are non-superimposable to each other then, they are said to be optical isomers.

Answer to Problem 73A

The correct option is (a):

Explanation of Solution

A molecule is said to be chiral molecule when all the attached groups to central carbon atom are different and lacks in plane of symmetry in the molecule. The molecules having chiral centres show optical isomerism as there are two mirror image representations possible for a molecule having chiral center in its structure and if the mirror images are non-superimposable to each other then, they are said to be optical isomers.

In order to find the same molecules, let (b) be the reference molecule to which other structures are compared as:

For structure (c), on rotating the structure in such a way that T comes at top like:

Thus, the obtained structure is same as that of (b).

For structure (d), on rotating and moving the structure in such a way that T comes at top and R at bottom like:

Thus, the obtained structure is same as that of (b).

Since, in (a) structure the orientation of atoms around carbon is different so, it is an optical isomer.

Hence, structure (b), (c) and (d) are same and (a) is the optical isomer.