Question

The maximum ease of abstraction of a hydrogen by a chlorine radical is shown in which of the following.

• A. $(C{H}_3{)}_{3}C-C{H}_3$
• B. $(C{H}_3{)}_{2}C{H}_3$
• C. $C_6{H}_{5}C{H}_3$
• D. $C{H}_2=CHC{H}_3$

Answer 1

The correct option is C $C_6{H}_{5}C{H}_3$

The ease of abstraction of H from a compound by chlorine radical is depends on the stability of the free radical formed.
More the stable of free radical, more will be the ease of abstraction of H radical.
Allylic and benzylic radicals are more stable than tertiary, secondary and primary radicals.
Comparing (c) and (d)
On comparison of allylic and benzylic radical both will undergo delocalisation and form resonance structure but benzylic radical shows more resonanting structures than allylic so benzylic radical is more stable than allylic.
Thus, (c) radical is most stable and the ease of abstraction of H by chlorine radical is maximum for (c)