Question

The C-Cl bond length in chlorobenzene is less than the C-Cl bond length in chloromethane because of the ________

(a) resonance effect in haloarenes

(b) difference in hybridisation of carbon  in C-Cl bond

(c) instability of phenyl cation

(d) possible repulsion between nucleophile and chlorobenzene

I got this question in homework.

I want to ask this question from Haloalkanes & Haloarenes topic in portion Haloalkanes and Haloarenes of Chemistry – Class 12

Answer 1

Right choice is (b) difference in hybridisation of carbon  in C-Cl bond

To explain I would say: In chlorobenzene, the C of C-Cl bond is sp^2 hybridised, whereas the C of C-Cl bond in chloromethane is sp^3 hybridised. Thus, there is more s character in the carbon of the C-Cl bond in chlorobenzene and as a result holds the electron pair of C-Cl bond more tightly.