Benzaldehyde can be prepared from benzene by passing vapours of ……. and ……… in its solution in presence of catalyst mixture of aluminium chloride and cuprous chloride. The reaction is known as …….. .

Options

A. `HCl, SnCl_(4)`, Rosenmund reduction
B. `CO, HCl`, Gattermann-Koch reaction
C. `CO_(2),H_(2)SO_(4)`, Clemmensen reduction
D. `O_(3),` alcohol, Wolff-Kishner reduction

Explanation

To prepare benzaldehyde from benzene, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The starting material is benzene (C6H6).
- The reactants required for the reaction are carbon monoxide (CO) and hydrochloric acid (HCl).

2. **Catalyst Requirement**:
- The reaction requires a catalyst, which is a mixture of aluminum chloride (AlCl3) and cuprous chloride (CuCl).

3. **Reaction Process**:
- The reaction involves passing the vapors of carbon monoxide and hydrochloric acid into the solution of benzene in the presence of the catalyst.
- The aluminum chloride and cuprous chloride facilitate the electrophilic substitution reaction.

4. **Formation of Benzaldehyde**:
- During the reaction, the carbon monoxide reacts with the benzene to form benzaldehyde (C6H5CHO).

5. **Name of the Reaction**:
- This reaction is known as the Gatterman-Koch reaction.

### Final Answer:
Benzaldehyde can be prepared from benzene by passing vapors of **carbon monoxide** and **hydrochloric acid** in its solution in the presence of a catalyst mixture of aluminum chloride and cuprous chloride. The reaction is known as the **Gatterman-Koch reaction**.

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