Predict the major product in the following reaction

Correct Answer: p-Hydroxyozobenzene

Step-by-Step Explanation:

1. Identify the Reactants and Reaction Conditions from the Image:
Based on the provided reaction scheme in the image, we have the following components:
• A benzenediazonium chloride molecule, represented by a benzene ring attached to a $-N^{+}\equiv N{\mathrm{Cl}}^{-}$ group.
• A phenol molecule, which consists of a benzene ring attached to a hydroxyl group ($-\mathrm{OH}$), labeled explicitly as "Phenol".
• Hydroxide ions (${\mathrm{OH}}^{-}$) shown above the reaction arrow, indicating that the reaction is carried out in a weakly basic/alkaline medium.

2. Mechanism of Diazonium Coupling (Azo Coupling):
• The benzenediazonium ion ($C_6{H}_5{N}_2^{+}$) acts as a weak electrophile.
• Phenol is a highly activated aromatic system due to the strong electron-donating resonance effect (+R effect) of the oxygen atom in the $-\mathrm{OH}$ group.
• In the presence of a weak base (${\mathrm{OH}}^{-}$, typically at pH 9-10), phenol is deprotonated to form the phenoxide ion:

$$C_6{H}_5\mathrm{OH}+{\mathrm{OH}}^{-}\to C_6{H}_5{O}^{-}+H_{2}O$$

The phenoxide ion is a much stronger nucleophile than neutral phenol, making it highly reactive toward the weak diazonium electrophile.

3. Regioselectivity and Product Formation:
• The diazonium ion attacks the para-position of the phenoxide ring because it is less sterically hindered compared to the ortho-position.
• The electrophilic aromatic substitution reaction yields a bright orange-colored azo compound containing the azo linkage ($-N=N-$):

$$C_6{H}_5{N}_2^{+}+C_6{H}_5{O}^{-}\to C_6{H}_5-N=N-C_6{H}_4-\mathrm{OH}$$

• The name of this major coupling product is p-hydroxyazobenzene (referred to as p-Hydroxyozobenzene in the options).