Question

Electrophilic substitution of aniline with bromine gives.
 
(a) 1,4,6-tribromo aniline
(b) 2,4,6-tribromo aniline
(c) 4-tribromo aniline
(d) 3-tribromo aniline

Answer 1

Hint: The electrophilic substitution reaction involves the replacement of an atom by the attack of nucleophile. The nucleophiles are electron pair donor spaces such as \[{I^ - }\],\[O{H^ - }\]and \[C{N^ - }\]etc. The addition of an electrophile in electrophilic substitution occurs at electronically rich sites of the reacting species.

Complete Step by Step Solution:
Aniline is an organic compound, and it is a very important starting material in organic chemistry. It contains a phenyl group attached to the amino group (\[N{H_2}\]). Furthermore, it is also considered the simplest aromatic amine.
Aniline possess the following resonating structure (Image 1) in which the electron pairs are present ortho, and para positions i.e., aniline has electronically rich ortho, and para positions.

Image: Resonating structures of aniline showing the electronically rich ortho and para positions.
During the bromination of aniline, the bromine act as an electrophile (electron loving species) and it entered at electronically rich position i.e., ortho and para position of aniline. As a result, the formation of 2, 4, 6-tribromo aniline occurred (Image 2).

Image: Bromination of aniline.

From the above points it is cleared that option (b) will be the correct answer.

Note: It is to be noted both cyanide and isocyanide are two different functional groups. In cyanide, the reaction happens at the C atom, that is, bond formation takes place like (-CN). In isocyanide, the reaction happens at the N atom, that is, bond formation occurs as (R-NC).