Question

When benzene is treated with carbon monoxide and hydrogen chloride in the presence of anhydrous aluminium chloride, benzaldehyde is formed. The reaction is known as

• A. Etard reaction
• B. Stephen reaction
• C. Hell-Volhard-Zelinsky reaction
• D. Gatterman-Koch reaction
• E. Aldol reaction

Hint:

The Gatterman-Koch reaction is one of the key methods for formylating benzene to benzaldehyde, a widely used aromatic aldehyde.

Answer 1

The Correct Option is D

The reaction involves the use of carbon monoxide (CO) and hydrogen chloride \text{(HCl) in the presence of anhydrous aluminum chloride } \text{AlCl}_3 \text{, which leads to the formation of benzaldehyde.} - Gatterman-Koch reaction (D): This is the correct name for the reaction where benzene reacts with carbon monoxide (CO) and hydrogen chloride (HCl) in the presence of AlCl₃ to form benzaldehyde. It is a formylation reaction and is a type of electrophilic aromatic substitution. - Etard reaction (A): The Etard reaction involves the oxidation of toluene to benzaldehyde, not the reaction of benzene with CO and HCl. - Stephen reaction (B): The Stephen reaction is used to convert benzene into benzylamine using cyanogen chloride (CNCl) and a reducing agent. It is not related to the formation of benzaldehyde. - Hell-Volhard-Zelinsky reaction (C): This is a halogenation reaction, where a carboxylic acid reacts with a halogen (like Br₂) in the presence of phosphorus to form an alpha-halo acid. It is not relevant here. - Aldol reaction (E): The Aldol reaction involves the condensation of aldehydes or ketones with activated carbonyl compounds to form β-hydroxy aldehydes or ketones, and it is unrelated to the formation of benzaldehyde from benzene. Thus, the correct answer is (D) Gatterman-Koch reaction, as it describes the formylation of benzene to form benzaldehyde.