How do you account for the formation of ethane during chlorination of methane?

Question

As compared with chlorocyclohexane, which of the following statements correctly apply to chlorobenzene?
The magnitude of negative charge is more on chlorine atom.
The C--Cl bond has partial double bond character.
C--Cl bond is less polar.
C--Cl bond is longer due to repulsion between delocalised electrons of the aromatic ring and lone pairs of electrons of chlorine.
The C--Cl bond is formed using \(sp^2\) hybridised orbital of carbon.
Choose the correct answer from the options given below:

Answer 1

Answer:

During chlorination of methane, ethane is formed as a by-product due to a free radical mechanism.

Explanation:

Chlorination of methane occurs in the presence of sunlight or UV light and proceeds through a free radical chain reaction.

Step 1: Initiation

Chlorine molecules undergo homolytic cleavage to form chlorine radicals.

Cl₂ → 2Cl·

Step 2: Propagation

Chlorine radical reacts with methane to form a methyl radical.

Cl· + CH₄ → CH₃· + HCl

The methyl radical reacts with chlorine to give chloromethane.

CH₃· + Cl₂ → CH₃Cl + Cl·

Step 3: Termination (formation of ethane)

Sometimes, two methyl radicals combine with each other.

CH₃· + CH₃· → C₂H₆

This coupling of methyl radicals leads to the formation of ethane.

Conclusion:

Thus, ethane is formed during chlorination of methane due to the recombination of methyl radicals in the termination step of the free radical chain reaction.

How do you account for the formation of ethane during chlorination of methane?

Solution and Explanation

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