`SN^(2)` reaction is a bimolecular reaction which takes places by the formation of `T.S.` Veolcity of the reaction depends on the concentration of the substrate as well as the nucleophile.
The reaction is favoureed by strong `Nu^(o-)` and in the presence of polar aprotic sovlent, optically active halides give. Walken inversion by `SN^(2)` mechanism. The presence of hero group (atom) at `beta-C` atom, unsaturation at `beta-C` and `(-overset(O)overset(||)(C)-)` group at `alpha-C` atomn favor `SN^(2)` mechanism.
Allyl halides and benzyl halides give `SN^(1)` and `SN^(2)` reactions. Allyl halides alos give `SN^(2)` mechanism `EDG` at ortho- and para- postions in benzyl halides favors `SN^(1)` mechanism, wheras `EWG` favors `SN^(2)` mechanism.
Which of the following will give `SN^(1)` reaction?

Options

A. `C_(2)H_(5)Br`
B.
C.
D. `CH_(2) = CH_(2)`

Answer

`c`

Explanation

Neighbouring group participation of `(COO^(o-))` group, with retention of configuration.