Question

Highlight, by clicking on, the asymmetric carbons (if any) in each structure. A selected atom will turn green. Indicate whether each compound contains a plane of symmetry (internal mirror plane) or not.

Answer 1

Concepts and reason

Chirality is the fundamental behind the optical activity of an organic molecule.

Chiral center: A‘C’ atom in a molecule becomes a chiral center when all the four valences of that atom are satisfied by chemically different groups. For a carbon to act as chiral center, it should be hybridization

The absence of symmetry is known as asymmetry. The carbon atom bonded to four unlike groups is called the asymmetric carbon which is also known as the chiral carbon.

In a non-chiral compound, the plane of symmetry is present and it does not have a chiral center.

The plane of symmetry: The plane of the mirror that cuts the compound into two equal halves.

Fundamentals

Representative example for chiral center and optical isomers is given below:

Here C is bonded to four different groups A, B C and D, Thus, it forms two optical isomers as the mirror images of each other

(1)

Assume the given structures as follows:

Structure 1:

Structure 2:

Structure 3:

There is no asymmetric carbon in methylcyclohexane.

(2)

If a molecule is not chiral, then it has a plane of symmetry.

Structure 1:

Structure 2:

Structure 3:

Ans: Part 1

The asymmetric carbons in the given structures are indicated as follows:

Part 2

The plane of symmetry element is indicated for the given structures as follows: