Statement I: Ethyl chloride is more reactive than vinyl chloride towards nucleophilic substitution reactions

Statement II: In Vinyl Chloride, the C–Cl is bonded to sp-hybridized carbon in alkenes.

Statement I is correct but statement II is false

The correct answer is option 3. Statement I is correct but statement II is false

Let us delve deeper into the explanations for both statements:

Statement I: Ethyl chloride is more reactive than vinyl chloride towards nucleophilic substitution reactions.

Ethyl chloride \((CH_3CH_2Cl)\) is a primary alkyl halide, where the carbon attached to the chlorine is sp3 hybridized. Primary alkyl halides tend to undergo nucleophilic substitution reactions, particularly \(S_N2\) (bimolecular nucleophilic substitution), more readily than other alkyl halides. This is because the nucleophile can attack the electrophilic carbon from the backside without significant steric hindrance.

On the other hand, vinyl chloride \((CH_2=CHCl)\) is an alkene where the carbon attached to the chlorine is \(sp^2\) hybridized. The double bond character in alkenes creates some partial pi-bond character between the carbon and the chlorine atom. This pi-bond character makes the carbon less accessible to nucleophiles, reducing the reactivity of vinyl halides towards nucleophilic substitution reactions, especially \(S_N2\) reactions. Instead, vinyl halides often undergo elimination reactions (such as \(E_2\)) due to the stability of the resulting alkene product.

Statement II: In vinyl chloride, the \(C–Cl\) bond is bonded to sp-hybridized carbon in alkenes.

This statement is incorrect. In vinyl chloride \((CH_2=CHCl)\), the carbon atom bonded to the chlorine is \(sp^2\) hybridized, not sp-hybridized. Alkenes have a carbon-carbon double bond consisting of one sigma bond and one pi bond. The carbon atoms participating in the double bond are \(sp^2\) hybridized, meaning they have three regions of electron density arranged in a trigonal planar geometry. The chlorine atom in vinyl chloride is bonded to one of these \(sp^2\) hybridized carbons.

The greater reactivity of ethyl chloride towards nucleophilic substitution (Statement I) is due to its primary alkyl halide nature, which favors \(S_N2\) reactions. The steric accessibility of the \(sp^3\) hybridized carbon in ethyl chloride allows nucleophiles to attack from the backside, leading to substitution.

Vinyl chloride, being an alkene with \(sp^2\) hybridized carbons (Statement II), does not undergo \(S_N2\) reactions effectively due to the partial double bond character and the resulting lack of steric accessibility at the carbon attached to the chlorine.

The correct understanding is that ethyl chloride is more reactive towards nucleophilic substitution reactions compared to vinyl chloride primarily because of the hybridization state of the carbon directly bonded to the chlorine atom. This difference in reactivity arises from the structural and electronic characteristics of primary alkyl halides versus alkenyl halides.

Therefore, the correct choice is Statement I is correct but statement II is false.