How many mono-chloro derivatives are possible, when 3-methylpentane is subjected to free radical chlorination?

When 3-methylpentane is subjected to free radical chlorination (Cl₂/hv), four distinct mono-chloro derivatives are possible. These arise due to substitution at four different types of carbon atoms (not counting duplicate or symmetric cases):

The possible positions for substitution are:

1. At the primary carbon at either end of the chain (two positions, but identical due to symmetry).
2. At the secondary carbons (next to terminal methyl, next to central methyl).
3. At the tertiary carbon (the carbon attached to three other carbons, i.e., where the methyl is attached).
4. At the methyl group attached as a side chain (next to the main chain).

By considering these, and as depicted in the image, the four mono-chloro derivatives are:

• 1-chloro-3-methylpentane
• 2-chloro-3-methylpentane
• 3-chloro-3-methylpentane
• 4-chloro-3-methylpentane

Final answer: 4 possible mono-chloro derivatives.