Question

The correct order of stability of alkyl radical is

• A. $\overset{\bullet}{C}H \left( CH _{3}\right)_{2}< \overset{\bullet}{C}H _{3}< \overset{\bullet}{C}H _{2} CH _{3}< \overset{\bullet}{C} \left( CH _{3}\right)_{3}$
• B. $\overset{\bullet}{C}\left( CH _{3}\right)_{3}<\overset{\bullet}{C}H \left( CH _{3}\right)_{2}< \overset{\bullet}{C}H _{3}< \overset{\bullet}{C}H _{2} CH _{3}$
• C. $\overset{\bullet}{C}\left( CH _{3}\right)_{3}<\overset{\bullet}{C}H \left( CH _{3}\right)_{2}< \overset{\bullet}{C}H _{2} CH _{3}< \overset{\bullet}{C}H _{3}$
• D. $\overset{\bullet}{C}H _{3}<\overset{\bullet}{C}H _{2} CH _{3}<\overset{\bullet}{C}H \left( CH _{3}\right)_{2}< \overset{\bullet}{C} \left( CH _{3}\right)_{3}$

Answer 1

Answer: (D)

As number of electron donating groups $\left(- CH _{3}\right)$ directly linked to carbon atom containing radical or cation increases, stability of free radical also increases. Thus, stability of alkyl radical increases as we proceed from primary to tertiary.
The correct order is as follows :