Question

Toluene, when treated with $ B{{r}_{2}}/Fe $ gives p-bromotoluene as the major product because the $ C{{H}_{3}} $ group:
(A) Is para directing.
(B) Is Meta directing.
(C) Activates the ring by hyperconjugation.
(D) Deactivates the ring.

Answer 1

Hint :We know that in toluene, methyl group is the substituent present on the ring. Methyl group shows a hyperconjugation effect and so, it is classified as an electron-donating group. Methyl group activates the ring and makes it easier to undergo ESR as compared to benzene.

Complete Step By Step Answer:
We are well aware that an electrophilic aromatic substitution reaction is the one in which an atom attached to the aromatic ring that is generally hydrogen has been replaced by an electrophile and some of the examples of such reactions includes: Aromatic nitration, Friedel-Crafts alkylation as well as acylation, aromatic sulfonation and halogenation. We should know that ortho-directing are the groups which substitute the hydrogen attached at ortho position or second carbon of the aromatic ring, p-directing are the one that substitute hydrogen at para position or third carbon of aromatic ring and the p directing are those that substitute hydrogen at para or fourth position in aromatic ring.
Also remember that activating groups are those that increase the rate of electrophilic aromatic substitution and deactivating groups are those that decrease the rate. An electrophilic aromatic substitution reaction is the one in which an atom which is attached to an aromatic system that is generally a hydrogen has been replaced by the electrophile and some of the examples are aromatic nitration, Friedel-Crafts alkylation as well as acylation, aromatic sulfonation and halogenation.

The above reaction is electrophilic substitution reaction. In which methyl group is ring activating and para directing group according to resonance.
Therefore, correct answer is option A and C.

Note :
Remember that electron-withdrawing groups will always deactivate the ring. Generally, they all are meta-directing but halogens are ortho and para-directing groups. The electron-donating groups are ring activating and ortho and para-directing groups. We also know that Alkyl groups are electron donating and cause the addition of electrophile on ortho and para positions.