Vinyl chloride does not give `S_(N)` reaction but allyl chloride gives. Explain.

Explanation

In vinyl chloride C-Cl bond is stable due to resonance (as in chlorobenzene).

Hence, `S_(N)` reaction in which Cl is replaced by nucleophile is not possible, In addition to this, `sp^(2)` hybridized carbon in more than `sp^(3)` carbon, hence removal of proton `(H*)` is easier than removal of halide (Cl). In allyl chloridn, S mactn is canier sinco allyl carbonium ion formed after removal of `Cl^(-)` is stabilized by resonance.
`CH_(2)=CH-CH_(2)Cl""to""underset("altyl carbonium ion")(CH_(2)=CH-CH_(2)+Cl)`
`CH_(2)=CH-overset(o+)CH_(2)iffoverset(o+)CH_(2)-CH=CH_(2)`