Question

The most unstable free radical among the following is

• A. R\(_3\)–C\(\cdot\)
• B. R–CH\(_2\)\(\cdot\)
• C. R\(_2\)–CH\(\cdot\)
• D. CH\(_3\)\(\cdot\)

Hint:

More the number of alkyl groups attached to a free radical, greater is its stability.

Answer 1

The Correct Option is D

Step 1: Recall stability order of alkyl free radicals.
Stability of free radicals increases with increase in alkyl substitution due to hyperconjugation and +I effect.
\[ \text{Tertiary}>\text{Secondary}>\text{Primary}>\text{Methyl} \]
Step 2: Analyze the given radicals.
R\(_3\)–C\(\cdot\) is tertiary (most stable).
R\(_2\)–CH\(\cdot\) is secondary.
R–CH\(_2\)\(\cdot\) is primary.
CH\(_3\)\(\cdot\) is methyl (least substituted).
Step 3: Conclusion.
CH\(_3\)\(\cdot\) has no alkyl group for stabilization, hence it is the most unstable.