Question

The molecular formula of diphenyl methane How many structural isomers are possible when one of the hydrogen is replaced by a chlorine atom?

• A. 6
• B. 4
• C. 8
• D. 7

Answer 1

The Correct Option is B

To solve this problem, we need to understand the structure of diphenylmethane and the concept of structural isomers.

Diphenylmethane has the molecular structure C_6H_5-CH_2-C_6H_5. It consists of two phenyl groups (C₆H₅) connected by a methylene bridge (CH₂).

When one hydrogen of diphenylmethane is replaced by a chlorine atom, we have to consider the positions where this substitution can occur. The possible substitution positions are:

1. On the methylene carbon (CH₂ group): This substitution leads to one possible isomer.
2. On the phenyl ring(s): Each phenyl ring has 5 available hydrogen positions for substitution. Given there are 2 phenyl rings, we consider symmetrical and equivalent substitutions.

Since substitution on the methylene bridge creates one unique isomer, let's focus on substitutions on the phenyl rings:

• Substitute at ortho (relative to bridge) position on any phenyl: 1 unique isomer as both rings are identical and swapping leads to the same structure.
• Substitute at meta position on any phenyl: 1 unique isomer due to ring symmetry.
• Substitute at para position on any phenyl: 1 unique isomer due to ring symmetry.

Therefore, combining these, we have the following structural isomers:

• 1 isomer with chlorine at methylene carbon.
• 1 ortho-substituted isomer on either phenyl ring.
• 1 meta-substituted isomer on either phenyl ring.
• 1 para-substituted isomer on either phenyl ring.

Summarizing the possibilities, we get a total of 4 structural isomers:

• 1 Chlorine on the methylene bridge.
• 3 positions on the phenyl rings (ortho, meta, para).

Thus, the correct answer is 4 structural isomers.

This confirms the correct option is 4.