Question

Write a note on directing effect of second substitution in benzene.

Answer 1

The directing effect of different groups of elements to a benzene is quite an easy task if you know the basic steps in organic chemistry.

If the first group is an ortho-para group it activates the benzene.

If the first group is a meta-group it deactivates the benzene.

In this way, you have to realize the places where the chemical groups are substituted.

Answer 2

Explanation:

• Benzene, when subjected to electrophilic substitution reactions, gives only one monosubstituted product.

• On further monosubstitution it gives three isomeric disubstituted products, ortho, meta and para, which these are not formed in equal proportions

• The position of second incoming substituent is determined by the nature of substituent already present in the benzene ring.

• The reactivity of the benzene ring is affected by the attached group and it determines the orientation of substitution.

eg : Phenol gives ortho and para disubstituted products as major products, while nitrobenzene gives m-disubstituted product as major product.