CBSE Class 12 Chemistry Amines Board Exam Notes

Chemical Properties Basic Strength of Amines
Amines act as Lewis bases due to the presence of lone pair of electrons on the nitrogen atom. More the Kb (dissociation constant of base), higher is the basicity of amines. Lesser the pKb higher is the basicity of amines. Aliphatic amines (R‐NH2) are stronger bases than NH3due to the electron releasing +I effect of the alkyl group. Among aliphatic methyl amines, the order of basic strength in aqueous solution is as follows:
(C2H5)2NH > (C2H5)3N > C2H5NH2> NH3 (CH3)2NH > CH3NH2> (CH3)3N > NH3
Aromatic amines are weaker bases than aliphatic amines and NH3, due to the fact that the electron pair on the nitrogen atom is involved in resonance with the π‐electron pairs of the ring.

BENZOYLATION:

protecting–NH2 by acetylation with acetic anhydride

NITRATION: Direct nitration of aniline is not possible as it is susceptible to oxidation Thus amino group is first protected by acetylation

In strongly acidic medium, aniline is protonated to form anilinium ion which is meta directing so it gives meta product also

SULPHONATION

Aniline does not undergo Friedel Craft reaction due to salt formation with aluminium chloride, the Lewis acid, which is used as a catalyst.
DIAZOTISATION:
Properties of benzene diazonium chloride