Amines Test - 7

Pyridine is less reactive than benzene towards electrophilic aromatic substitution because nitrogen is more electronegative than carbon and acts as an electron withdrawing group.

Due to resonance, this position is electron rich and steric hindrance will be the least.

A is the intermediate formed by nucleophilic attack by CH₃NH₂ on the carbonyl carbon of CH₃COCl.

The F.C. alkylation and F.C. acylation reaction take place in presence of Anhyd. AlCl₃, which is a Lewis base as it is electron deficient, it attacks the lone pair on nitrogen in aniline and forms an insoluble complex which precipitates out and reaction does not happen further.
C₆H₅NH₂ + AlCl₃  → C₆H₅NH₂⁺AlCl₃

In this reaction benzene and phenol get coupled through -N=N- linkage. The compounds containing this type of linkage are called azo compounds.

C₆H₅N₂ ⁺Cl^- + C₆H₅OH → p-C₆H₅N=NC₆H₄OH (dye)

Due to their positive charge, diazonium cations may participate in an electrophilic aromatic substitution as an electrophile. The electrophilic reaction center is the terminal nitrogen of the -N=N⁺group. As a result, two aromatic compounds are coupled by a -N=N- group. This is known as the azo group (diazo group). The corresponding reaction is called diazonium coupling (diazo coupling, azo coupling). However, the electrophilicity of diazonium ions is only relatively weak, as their positive charge is delocalized.

Benzoic acid reacts with NaOH to form sodium benzoate, this is a neutralisation reaction where acid reacts with a base to give salt and water.
C₆H₅COOH + NaOH →→ C₆H₅COO^-Na^₊ + H₂O

Carboxylic acids react with alcohol in acidic medium to form sweet smelling compounds called esters, this reaction is called esterification reaction.
CH₃COOH + CH₃OH + H⁺  →  CH₃COOCH₃ + H₂O