Question

Write resonating structures of arylamines. Explain why arylamines exhibit basic properties. Write chemical equations of the reaction of preparation of amine from nitro and nitrile compounds.

Hint:

Arylamines are less basic than aliphatic amines due to resonance, which delocalizes the lone pair on nitrogen.

Answer 1

Resonating Structures of Arylamines: Arylamines, such as aniline (\( C_6H_5NH_2 \)), exhibit resonance due to the delocalization of the lone pair of electrons on the nitrogen atom into the benzene ring. \[ \text{Structure 1:} \quad \ce{C6H5NH2} \quad \rightarrow \quad \text{Structures showing delocalized electrons}. \] Basic Properties: Arylamines are basic because the lone pair of electrons on the nitrogen atom can accept a proton (\( H^+ \)). However, resonance decreases the availability of the lone pair, making them less basic than aliphatic amines. Preparation of Amines: 1. From Nitro Compounds: \[ \ce{RNO2 + 6[H] -> RNH2 + 2H2O} \quad \text{(Reduction with Sn/HCl or catalytic hydrogenation)}. \] 2. From Nitriles: \[ \ce{RCN + 2[H] -> RCH2NH2} \quad \text{(Reduction with LiAlH4)}. \]