Question

How can one identify benzylic carbons?

Answer 1

Hint: To identify a benzylic carbon, first we should know about the benzylic position and benzylic position is that position which is present exactly next or to the first position of the benzene ring.

Complete answer:
As we know that benzylic position is the adjacent next attached position after a benzene ring, so benzylic carbon is that saturated carbon which is directly attached to the benzene ring by occupying first position. Some examples if benzylic carbons are as follow:
-In the ethyl benzene, benzylic carbon is shown as follow:
 

In the above diagram carbon which is present in ${\text{ - C}}{{\text{H}}_{\text{2}}}$ group is a benzylic carbon, because it is saturated in nature as well as attach to the benzene ring directly.
-In 1-ethyl-2-methyl Benzene, benzylic carbon is shown as follow:

In the above diagram two benzylic carbons are present on the first as well as on the second position of the benzene ring. Carbon of ${\text{ - C}}{{\text{H}}_{\text{2}}}$ of ethyl group on the first position & carbon of ${\text{ - C}}{{\text{H}}_3}$ group on the second position are saturated in nature and directly attached to the benzene ring, that’s why they are benzylic carbon of the above compound.

Note:
Here some of you may get confused by hearing the name benzylic carbon & may think that carbons of the benzene ring are termed as benzylic carbon, but that assumption will be wrong and you will never identify correct benzylic carbon.