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:

• A. B, C and D Only
• B. A, C and E Only
• C. A, D and E Only
• D. B, C and E Only

Hint:

In chlorobenzene, resonance and \(sp^2\) hybridisation significantly affect bond polarity and bond length.

Answer 1

The Correct Option is C

To determine which statements correctly apply to chlorobenzene as compared to chlorocyclohexane, let's examine each statement:

1. The magnitude of negative charge is more on chlorine atom:

   In chlorobenzene, due to resonance, the lone pair of electrons on chlorine is delocalized into the benzene ring, thereby reducing the negative charge localized on the chlorine atom itself. On the other hand, in chlorocyclohexane, no resonance stabilizes or delocalizes the lone pair of electrons, which means more negative charge remains on the chlorine atom. Thus, this statement is correct.

2. The C--Cl bond has partial double bond character:

   In chlorobenzene, the C--Cl bond exhibits partial double bond character because of resonance. The lone pair of electrons on the chlorine atom overlaps with the π-electrons of the benzene ring, creating a double bond-like character. This statement is correct for chlorobenzene.

3. C--Cl bond is less polar:

   In chlorobenzene, due to the resonance and partial double bond character of the C--Cl bond, the bond is less polar compared to chlorocyclohexane, where the C--Cl bond is purely single and thus more polar. This statement is true for chlorobenzene.

4. C--Cl bond is longer due to repulsion between delocalised electrons of the aromatic ring and lone pairs of electrons of chlorine:

   Actually, due to the partial double bond character in chlorobenzene, the C--Cl bond is shorter compared to chlorocyclohexane which has a pure single bond. Thus, this statement is incorrect.

5. The C--Cl bond is formed using sp^2 hybridised orbital of carbon:

   In chlorobenzene, the carbon atom is sp^2 hybridized due to its bonding in the aromatic ring. This results in forming the C--Cl bond using an sp^2 hybridised orbital. This statement is correct.

Given the analysis:

• Statement A is correct: The magnitude of negative charge is more on the chlorine atom of chlorocyclohexane than in chlorobenzene.
• Statement B is correct: The C--Cl bond in chlorobenzene does have partial double bond character due to resonance.
• Statement C: The given statement about the C--Cl bond being less polar is inferred correctly.
• Statement D is incorrect: For chlorobenzene, the C--Cl bond is not longer but shorter due to partial double bond character.
• Statement E is correct: The C--Cl bond is formed using sp^2 hybridised orbital in chlorobenzene.

Hence, the answer is: A, D and E Only