Aniline basicityMediumQuestion 820005
Question
Aniline (C₆H₅NH₂) is a weaker base than cyclohexylamine because:
- ALone pair on N delocalises into the aromatic ring, reducing availability to accept H⁺Correct
- BPhenyl group is larger
- CAniline has fewer lone pairs
- DCyclohexylamine has lower pKb
Correct answer
Lone pair on N delocalises into the aromatic ring, reducing availability to accept H⁺
Explanation
In aniline, the lone pair of N is partially delocalised into the benzene ring (+M effect), reducing its electron density and hence basicity. Cyclohexylamine has no such delocalisation. pKb: aniline (9.4) >> cyclohexylamine (3.36).