Electrophilic Substitution Reaction

Question 1

What is the peculiarity of electrophilic substitution reaction in amines?

Answer 1

1)The -NH2 group is ortho and para directing
2) powerful activating group.
2) therefore the reaction are vigorous

Question 2

Bromination?

Answer 2

Aniline reacts with bromine water in room temperature to form a white precipitate of 2,4,6- tribromoaniline

Question 3

How to prepare parabromo aniline and ortho bromoaniline ?

Answer 3

To prepare para bromoaniline and ortho bromoaniline we first reduce the activating power of - NH 2 group by protecting it with acetylation with acetic chloride or acetic anhydride , resulting in acetanilide which then subjected to bromination with Br2 in acetic acid flowed by hydrolysis giving p- bromoaniline as the major product..

Question 4

Nitration

Answer 4

Direct nitration of aniline with conc.HNO3 and conc.H2SO4 will result in the formation of ortho ,para and meta directing nitroaniline and also some tarry products

Question 5

Sulphonation

Answer 5

Aniline reacts with concentrated sulphuric acid to form anilinium hydrogensulphate which on heating
with sulphuric acid at 453-473K produces p-aminobenzene sulphonic acid, commonly known as sulphanilic
acid, as the major product. Sulphanilic acid contains both acidic and basic groups and so it forms
internal salts called zwitter ions.

Reaction refer note

Aniline does not undergo Friedel-Crafts reaction (alkylation and acylation) since it form salt with
anhydrous aluminium chloride, which is used as catalyst in the reaction.