Question

Draw the structure of the activated benzene ring and the diazonium ion used in the synthesis of each of the following compounds, whose structures can be found on page 607.

a. butter yellow

b. methyl orange

Short answer

Arenediazonium ions serve as electrophiles in an electrophilic aromatic substitution reaction. Only highly activated benzene rings like phenols and anilines undergo electrophilic aromatic substitution with arene diazonium ion electrophiles.

Step-by-step solution

Diazonium ion

Arenediazonium ions serve as electrophiles in an electrophilic aromatic substitution reaction. Only highly activated benzene rings like phenols and anilines undergo electrophilic aromatic substitution with arene diazonium ion electrophiles.

Structure of the activated benzene ring and the diazonium ion used for the synthesis of various compounds

a. The structure of butter yellow is given below.

The structures of the activated benzene and the diazonium ion used in the synthesis of butter yellow are given below.

Structures of the activated benzene and the diazonium ion used in the synthesis of butter yellow

Aniline creates the diazonium ion in reaction with nitrous acid in the presence of phenol and HCl. It adds N-dimethylaniline at the para position Nelectrophilic substitution reaction, forming butter yellow.

b. The structure of methyl orange is given below.

The structures of activated benzene and the diazonium ion used to synthesize methyl orange are given below.

Structures of activated benzene and the diazonium ion used for the synthesis of methyl orange

The reactant4-aminobenzoic acid reacts with nitrous acid in the presence of phenol and HCl to create the diazonium ion. It adds N-dimethylaniline at the para position N by electrophilic substitution reaction generating methyl orange.