Question

The increasing order of stability of the following radicals is.

• A. $\left( CH_{3} \right)_{2}\overset{.}{C}H < \left( CH_{3} \right)_{3}\overset{.}{C} < \left( C_{6}H_{5} \right)_{2}\overset{.}{C}H < \left( C_{6}H_{5} \right)_{3}\overset{.}{C}$
• B. $\left( C_{6}H_{5} \right)_{3}\overset{.}{C} < \left( C_{6}H_{5} \right)_{2}\overset{.}{C}H < \left( CH_{3} \right)_{3}\overset{.}{C} < \left( CH_{3} \right)_{2}\overset{.}{C}H$
• C. $\left( C_{6}H_{5} \right)_{2}\overset{.}{C}H < (C_{6}H_{5})_{3}\overset{.}{C} < \left( CH_{3} \right)_{3}\overset{.}{C} < (CH_{3})_{2}\overset{.}{C}H$
• D. $\left( CH_{3} \right)_{2}\overset{.}{C}H < (CH_{3})_{3}\overset{.}{C} < \left( C_{6}H_{5} \right)_{3}\overset{.}{C} < \left( C_{6}H_{5} \right)_{2}\overset{.}{C}H$

Answer 1

Answer: (A)

$\left( CH_{3} \right)_{2}\overset{.}{C}H < \left( CH_{3} \right)_{3}\overset{.}{C} < \left( C_{6}H_{5} \right)_{2}\overset{.}{C}H < \left( C_{6}H_{5} \right)_{3}\overset{.}{C}$

Answer 2

: On the basis of hyperconjugation, the order of stability of free radicals is as follows t > s > p. Benzyl free radicals are stabilized by resonance and hence are more stable than alkyl free radicals. More the number of phenyl groups attachend to the carbon atom, more is the stability of free radical.