Question

During nitration of aniline, m-nitroaniline is also obtained. Why?

Answer 1

Hey.

During nitration of aniline, m - nitroaniline is also obtained .

 If direct nitration of aniline is carried, in the presence of these acids, aniline gets protonated to form anilinium ion. The anilinium group, no longer possessing a free electron pair (tied up with H^+), deactivates the aromatic ring toward electrophilic substitution,also anilinium ion which is meta directive. Hence nitration of aniline gives meta derivative along with ortho and para. Therefore nitration of aniline is carried out by first protecting amino group by acetylation and meta nitroaniline is obtained. 

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Answer 2

Heyaa...

Aniline is basic in nature so when it reacts with acids (conc HNO3+H2SO4-nitration mixture) it forms anilinium ion

Anilinium ion is meta directing in nature

Products of this reaction would be of Ortho,para,meta nitro aniline,but as anilinium ion is meta directing major product would be m-nitroaniline

Hope it helpss...