Question

The structure of major product X and Y formed in the following reaction are: $CHCl_3 \xrightarrow[Light]{O_2} (X) \xrightarrow[AlCl_3]{C_6H_6(excess)} (Y)$

• A. HO-CCl$_3$
• B. Phosgene
• C. Phosgene
• D. CCl$_2$

Answer 1

Answer: (C)

The third option matches the derived products where X is phosgene ($COCl_2$) and Y is benzophenone ($Ph-CO-Ph$).

Answer 2

Step-by-step Derivations:

1. Formation of Product X: The first reaction involves the oxidation of chloroform ($CHCl_3$) in the presence of oxygen ($O_2$) and light. This is a well-known reaction where chloroform decomposes to form phosgene ($COCl_2$). This reaction is a significant safety concern as phosgene is a highly toxic gas. The reaction can be written as: $2CHCl_3 + O_2 \xrightarrow{Light} 2COCl_2 + 2HCl$ Therefore, the major product X is phosgene ($COCl_2$).

2. Formation of Product Y: The second reaction involves the reaction of product X ($COCl_2$) with excess benzene ($C_6H_6$) in the presence of aluminum chloride ($AlCl_3$). This is a Friedel-Crafts acylation reaction. Phosgene ($COCl_2$) is a di-acyl chloride, meaning it has two acyl chloride functionalities.

• First Acylation: Phosgene reacts with one molecule of benzene to form benzoyl chloride. $Cl-C(=O)-Cl + C_6H_6 \xrightarrow{AlCl_3} C_6H_5-C(=O)-Cl + HCl$ (Benzoyl chloride)

• Second Acylation: Since benzene is in excess, the benzoyl chloride formed can further undergo Friedel-Crafts acylation with another molecule of benzene. $C_6H_5-C(=O)-Cl + C_6H_6 \xrightarrow{AlCl_3} C_6H_5-C(=O)-C_6H_5 + HCl$ (Benzophenone)

Therefore, the major product Y is benzophenone ($C_6H_5-C(=O)-C_6H_5$ or $Ph-CO-Ph$).

Conclusion: Based on the analysis, product X is $COCl_2$ and product Y is $Ph-CO-Ph$.