What product is obtained when chloroform reacts with oxygen in presence of light?

Phosgene gas

The correct answer is Option (1) → Phosgene gas.

The reaction of chloroform (\(\text{CHCl}_3\)) with oxygen in the presence of light is an example of a photochemical reaction, where light energy initiates the transformation of reactants into products. Here’s a detailed explanation of the process:

Chloroform Structure and Properties

Chloroform is a colorless, volatile liquid with the chemical formula \(\text{CHCl}_3\). It is used as a solvent and is known for its anesthetic properties. Chloroform is also a halogenated hydrocarbon, which makes it susceptible to reactions with oxygen, especially under the influence of light.

Reaction Conditions

Light: The presence of light (often ultraviolet light) provides the necessary energy to break chemical bonds in chloroform, allowing the reaction to proceed.

Oxygen: The presence of oxygen is crucial as it acts as an oxidizing agent in the reaction.

Mechanism of the Reaction

The reaction proceeds through a series of radical mechanisms:

Initiation:

The light energy causes the homolytic cleavage of the \(\text{C-Cl}\) bonds in chloroform, generating \(\text{CCl}_2\) (dichloromethyl) radicals and chlorine radicals \((\text{Cl}\cdot)\).

\(\text{CHCl}_3 \overset{\text{h}\nu}{\longrightarrow} \text{CCl}_2 \cdot + \text{Cl} \cdot\)

Propagation:

The generated chlorine radicals can react with oxygen to form \(\text{ClO}\) (chlorine monoxide) radicals.

\(\text{Cl} \cdot + \text{O}_2 \longrightarrow \text{ClO} \cdot + \text{O}\)

The \(\text{CCl}_2\) radical can then react with oxygen to produce phosgene:

\(\text{CCl}_2 \cdot + \text{O}_2 \longrightarrow \text{COCl}_2 + \text{Cl} \cdot\)

Termination:

The reaction can terminate through various pathways, including the combination of radicals to form stable products.

Products of the Reaction
The primary product formed in this reaction is phosgene gas (\(\text{COCl}_2\)), a toxic compound that has been used in chemical warfare and as an industrial chemical

Safety Considerations

Phosgene is highly toxic, and its formation from chloroform is a significant health hazard. It is essential to conduct such reactions in a controlled environment, such as a fume hood, and with proper protective equipment.

Other Potential Products

While phosgene is the main product, there can also be the formation of other chlorinated compounds and radicals, depending on the reaction conditions and the extent of the reaction. However, under typical conditions of chloroform reacting with oxygen and light, phosgene is predominantly formed.

Conclusion

In summary, the reaction of chloroform with oxygen in the presence of light leads to the formation of phosgene gas through radical mechanisms. Understanding this reaction highlights the importance of safety and the potential hazards associated with the use of chloroform and other halogenated hydrocarbon