Question

Identify the reactant

• A. H\(_2\)O
• B. HCHO
• C. CO
• D. CH\(_3\)CHO

Hint:

Gattermann–Koch reaction: \(C_6H_6 + CO + HCl \xrightarrow{AlCl_3/CuCl} C_6H_5CHO\).

Answer 1

The Correct Option is C

Step 1: Identify reaction shown.
Benzene is converted into benzaldehyde in presence of \(AlCl_3\) and HCl.
This is the Gattermann–Koch reaction.
Step 2: Reactants of Gattermann–Koch reaction.
The formyl group \(-CHO\) is introduced using:
\[ CO + HCl \]
in presence of \(AlCl_3\) (and often CuCl).
Step 3: Conclusion.
So the missing reactant is carbon monoxide \(CO\).
Final Answer:
\[ \boxed{\text{(C) CO}} \]