Question

Which group is meta directing?
(A) $- CC{l_3}$
(B) $- OH$
(C) $- N{H_2}$
(D) $- C{H_3}$

Answer 1

In this question we have been given four groups$- CC{l_3}$, $- OH$, $- N{H_2}$, $- C{H_3}$ out of which we need to tell which of them is a meta directing group, for that we need to check which of these groups are deactivating or activating. And we know activating groups are ortho and para directing and deactivating groups are meta directing.

Complete step by step solution:
We have been provided the four groups$- CC{l_3}$, $- OH$, $- N{H_2}$, $- C{H_3}$ out of which we need to tell which of them is a meta directing group.
Now, we know that activating groups are ortho and para directing and are electron-donating groups which contain lone pairs. The other is a deactivating group which is meta directing and an electron-withdrawing group which does not contain the lone pair.
Now, we have the group $- CC{l_3}$, and as we know chlorine is more electronegative than carbon. So, it pulls the electron density towards itself and acts as a deactivating group on benzene rings which generally give meta substituents. And we know the deactivating group is the electron-withdrawing group which does not contain the lone pair.
Now, the other three groups $- OH$, $- N{H_2}$, $- C{H_3}$ contain lone pairs, therefore, it is an activating group which is ortho and para directing also known as electron-donating group.
So, from this we can say that out of these 4 groups $- CC{l_3}$is a meta directing group.

Therefore, option (A) is correct.

Note: In this question, we must try to check the presence of lone pairs of all these groups to classify them into activating or deactivating, so that we can find whether they are meta directing or ortho and para directing.