Question

Correct order of rate of photochlorination for following compounds is:

• A. II < I < III
• B. I < II < III
• C. III < I < II
• D. II < III < I.

Answer 1

The correct option is A II < I < III

Photochlorination is the method of bonding of a chlorine atom with a carbon atom in the presence of light. The rate depends upon the fact that how easily a hydrogen atom can be replaced by a chlorine atom. Due to steric hindrance of the methyl group, tertiary groups have the most highest rate. Now since, C-H and C-D both are primary carbon atoms, the rate of photocholrination will depend on the bond strength. The bond strength of C-D bond is greater than that of C-H bond due to heaviness of D atom, hence after tertiary group C-H bond will be easily broken and H atom will be replaced by a Cl atom.

Therefore, the correct option will be A) II < I < II