• Dilute mineral acids convert amines into their salts. These salts react with aqueous hydroxides to regenerate the amine.
Hence it is clear that although amines are more basic than water, they are less basic than hydroxide ions.
• Amines are more basic than alcohols
R-OH + H+ ⇌ ROH2+ Alkyl oxonium ion
R-NH2 + H+ ⇌ RNH3+ Alkyl ammonium ion
As nitrogen is less electronegative than oxygen it has a higher tendency to donate lone pair of electrons. Hence the stability of the alkyl ammonium ion relative to the amine is stronger than the stability of the alkyl oxonium ion relative to the alcohol. The reason for this is that an atom with low electronegativity can bear a positive charge more easily.
• Aliphatic primary amines are more basic than aniline. The reason for the low basicity of aniline is because the lone pair of electrons on the nitrogen of aniline is not easily available to a proton due to it being delocalized on to the aromatic ring by resonance.
• Amides are less basic than amines. It is because the pair of electrons on the nitrogen of the amide group is delocalized on to the carbonyl group by resonance.
