Question

Identify major product "X" formed in the following reaction :

• A.
• B.
• C.
• D.

Answer 1

The Correct Option is C

The reaction depicted in the image is known as the Gattermann-Koch reaction, which is a method for formylating aromatic rings, where benzene reacts with carbon monoxide (CO) and hydrochloric acid (HCl) in the presence of a catalyst such as anhydrous aluminum chloride (AlCl₃) and copper(I) chloride (CuCl). The reaction typically results in the introduction of a formyl group (-CHO) onto the aromatic ring.

Here, benzene is the starting material, and the formation of benzaldehyde is the major product. This is because the CO and HCl react together to form the formyl chloride (HCOCl) in situ, which then reacts with benzene to yield the formylated product, benzaldehyde.

To confirm this, let's examine why the given answer is correct and why other options are incorrect:

• Compound 1: This option is incorrect because it does not represent a formylated product, i.e., lacks the aldehyde (-CHO) group.
• Compound 2: This compound is not expected from the Gattermann-Koch reaction. It typically relates to different reactions such as Friedel-Crafts acylation.
• Compound 3 (Correct): This is benzaldehyde, the expected major product formed by the introduction of a formyl group onto benzene in the presence of AlCl₃/CuCl catalysts.
• Compound 4: Similar to Compound 1, this option does not represent an aromatic aldehyde, which rules it out.

Hence, the major product "X" formed in this reaction is Benzaldehyde.

Answer 2

The reaction is the Gattermann–Koch reaction, which involves the formylation of benzene to produce benzaldehyde (\(C_6H_5CHO\)). In the presence of carbon monoxide (CO), hydrogen chloride (HCl), and anhydrous AlCl\(_3\)/CuCl, the formyl group (CHO) is introduced into the benzene ring.

\(C_6H_6 + CO + HCl \xrightarrow{\text{AlCl}_3/\text{CuCl}} C_6H_5CHO\)

Thus, the major product \(X\) is benzaldehyde (3).
Thus the correct answer is Option 3.