Question

For the given reaction :



$\stackrel{\bullet }{B}r$ will abstract which of the hydrogen most readily ?

• A. Hydrogen (a)
• B. Hydrogen (b)
• C. Hydrogen (c)
• D. Hydrogen (d)

Answer 1

The correct option is A Hydrogen (a)

Halogenation reaction with Bromine is highly selective, it will abstract that hydrogen which forms the most stable free radical.
Order of stability of free radical is :
$1^{\circ }<2^{\circ }<3^{\circ }$
When Hydrogen (a) is abstracted, $3^{\circ }$ free radical is obtained.
When Hydrogen (b) is abstracted, $2^{\circ }$ free radical is obtained.
When Hydrogen (c) is abstracted, $1^{\circ }$ free radical is obtained.
When Hydrogen (d) is abstracted, $2^{\circ }$ free radical is obtained.
So, Hydrogen (a) will be abstracted most readily forming the given major product