Question

The reaction 

Options

• Rosenmund’s reaction

• Stephen’s reaction

• Cannizzaro’s reaction

• Gatterman-Koch reaction

Answer 1

Gatterman-Koch reaction

Explanation:

Benzene is formylated by CO + HCl in the presence of a Lewis acid (AlCl₃) with CuCl as promoter to give benzaldehyde (an electrophilic aromatic substitution where a formyl-type electrophile, often written as an acylium/formyl complex, attacks the ring). This specific variant using CO/HCl is called the Gattermann–Koch (or Gattermann–Koch formylation); the original Gattermann reaction uses HCN + HCl instead.