Question

The ease of formation of free radicals follows which of the following order?

• A. $1°>2°>3°>{\mathrm{CH}}_3$
• B. $2°>1°>3°>{\mathrm{CH}}_3$
• C. $3°>2°>1°>\mathrm{CH}3$
• D. ${\mathrm{CH}}_3>3°>2°>1°$

Answer 1

The correct option is C

$3°>2°>1°>\mathrm{CH}3$

The explanation for the correct option:

Option(C):$3°>2°>1°>\mathrm{CH}3$

• The ease of formation of the free radicals depends on their stability, hence the radical which is more stable will be more easily formed.
• The stability of the free radicals increases due to the presence of Alkyl groups,
• The Alkyl groups give more stability to the free radical due to the increased +I effect.
• Thus the ease of formation of the free radicals can be given in the order :$3°>2°>1°>\mathrm{CH}3$

The explanation for the incorrect option:

Option(A):$1°>2°>3°>{\mathrm{CH}}_3$

• As the free radicals with more number of alkyl groups tend to form easily, the ease of formation of the free radicals will be in the order :$3°>2°>1°>\mathrm{CH}3$
• Hence, the given option does not represent the correct concept.

Option(B):$2°>1°>3°>{\mathrm{CH}}_3$

• The given order for the ease of formation of the free radicals is in the incorrect order.
• Thus, the given option is the incorrect one.

Option(D):${\mathrm{CH}}_3>3°>2°>1°$

• As the free radicals with more number of alkyl groups tend to form easily, the ease of formation of the free radicals will be in the order :$3°>2°>1°>\mathrm{CH}3$
• Hence, the given option does not coincide with the correct concept.

Hence, The ease of formation of free radicals follows the order: $3°>2°>1°>\mathrm{CH}3$, option (C) is the correct answer.