Give reason

(i)

• Friedel Crafts reaction takes place in the presence of AlCl₃ which is acidic in nature but aniline is basic.

• This leads to aniline forming a salt.

• The acquired positive charge on the nitrogen atom makes it a strong deactivating group and hence aniline does not undergo Friedel Crafts reaction.

(ii)

• In p-Methylaniline, Aniline is substituted with an electron releasing methyl group.

• This increases the electron density on the nitrogen atom making it more available for donation. Thus, p-Methylaniline is basic in nature.

• In the case of p-Nitroaniline, Aniline is substituted with an electron withdrawing nitro group which decreases the electron density on the nitrogen atom.

• This makes the lone pair of electrons on nitrogen less available for donation, making it less basic.

• Thus, p-Methylaniline is more basic than p-Nitroaniline.

(iii)

• The lone pair of electrons on nitrogen atom of aniline shows resonancewith the aromatic ring.

• Also, as discussed above, aniline is basic in nature because it can donate these lone pair of electrons.

• Acetylation of aniline is necessary because else it will react with the catalyst used in electrophilic substitution reactions (AlCl₃) which is acidic in nature to form the salt of aniline.