Question

An ' Assertion' and a 'Reason' are given below. Choose the correct answer from the following options.
Assertion (A) : Vinyl halides do not undergo nucleophilic substitution easily.
Reason (R) : Even though the intermediate carbocation is stabilized by loosely held $\pi$-electrons, the cleavage is difficult becuase of strong bonding.

• A. Both (A) and (R) are wrong statements
• B. Both (A) and (R) are correct statements and (R) is the correct explanation of (A)
• C. Both (A) and (R) are correct statements but (R) is not the correct explanation of (A)
• D. (A) is a correct statement but (R) is a wrong statement.

Answer 1

Answer: (D)

Vinyl halide $CH_2=CH-Cl$ do not undergo SN reaction
This is due to formation of highly unstable carbocation $(CH_2 = C^{\oplus}H)$ ; which cannot be delocalised by the $\pi$-electron, also C-Cl has double bond character because of resonance