Question

Which of the following is secondary radical:
A) $C{H_2} = CH$
B) ${(C{H_3})_3}C - $
C) ${C_6}{H_5}$
D) $C{H_3}{\left( {C{H_2}} \right)_2} - C{H_2} - $

Answer 1

Hint:We should remember that secondary radical is a radical in which the radical carbon is attached with two carbon atoms. A secondary alkyl radical is an alkyl radical in which the carbon atom bearing the unpaired electron is bonded to two carbon atoms.


Complete answer:
Let us know about radicals first and understand the concept:
Radical, also called Free Radical, in chemistry, a molecule that contains at least one unpaired electron. Most molecules contain even numbers of electrons, and the covalent chemical bonds holding the atoms together within a molecule normally consist of pairs of electrons jointly shared by the atoms linked by the bond.
Now we see that:
In $C{H_2} = CH$ carbon the targeted carbon is attached to one methyl group so it is a primary radical.
In ${(C{H_3})_3}C - $ the targeted carbon is attached to three methyl groups therefore it is tertiary radical.
In ${C_6}{H_5}$ each carbon atom in the ring is attached to two different carbons hence it is secondary.
In organic chemistry, the phenyl group or phenyl ring is a cyclic group of atoms with the formula ${C_6}{H_5}$. Phenyl groups are closely related to benzene and can be viewed as a benzene ring, minus a hydrogen, which may be replaced by some other element or compound to serve as a functional group. Phenyl groups have six carbon atoms bonded together in a hexagonal planar ring, five of which are bonded to individual hydrogen atoms, with the remaining carbon bonded to a substituent. Phenyl groups are commonplace in organic chemistry. Although often depicted with alternating double and single bonds, phenyl groups are chemically aromatic and show nearly equal bond lengths between carbon atoms in the ring.
That formula must be from a benzene molecule that is missing a hydrogen. Any carbon atom in a molecule that is bonded to two carbons and has an unbonded electron makes that molecule a secondary radical.
In $C{H_3}{\left( {C{H_2}} \right)_2} - C{H_2} - $ the targeted carbon is attached to one carbon hence it is primary radical .

So,the correct option is C.
Note:Radical are formed by homolytic fission and they are highly reactive.Generally,the reactions with radicals are photolytic and light energy is required to form a radical;because of high reactivity mostly chain reactions occur.