Question

The Gattermann-Koch reaction is used in the industrial preparation of benzaldehyde. The electrophile involved in this reaction is

• A. HCO+
• B. HCl + CO$_2$ + anhydrous AlCl$_3$
• C. CO+
• D. CO + anhydrous AlCl$_3$

Answer 1

The Correct Option is A

Benzaldehyde is synthesized from benzene using the Gattermann-Koch reaction, an electrophilic aromatic substitution. This process requires generating an electrophile that then reacts with the benzene ring. To determine the correct electrophile, consider the following options:

• HCO⁺
• HCl + CO₂ + anhydrous AlCl₃
• CO⁺
• CO + anhydrous AlCl₃

In the Gattermann-Koch reaction, the electrophile is produced when carbon monoxide (CO) interacts with hydrochloric acid (HCl) in the presence of a Lewis acid catalyst, typically anhydrous aluminum chloride (AlCl₃). This interaction forms the formyl cation (HCO⁺), which subsequently functions as the electrophile, reacting with benzene to yield benzaldehyde.

Consequently, the specific electrophile participating in the Gattermann-Koch reaction is: HCO⁺.