Among the following, the strongest nucleophile is:

Options

A. `C_(2)H_(5)SH`
B. `CH_(3)COO^(-)`
C. `CH_(3)NH_(2)`
D. `NC CH_(2)^(-)`

Answer

A

Explanation

Although `CH_(3)COO^(-)` and `NC CH_(2)^(-)` are -vely charged but -ve charge on them is stabilized by resonance and hence are less willing to donate a pair of electrons than `C_(2)H_(5)SH` and `CH_(3)NH_(2)`

Among `C_(2)H_(5)SH` and `CH_(3)NH_(2), S` is less electronegative than N and hence `C_(2)H_(5)SH` is more willing to donate a pair of electrons. Thus `C_(2)H_(5)SH` is the strongest nuclephile. Since `CHO^(-)` is a strong nucleophilic as well as a strong base, therefore, it can either bring about substitution or elimination. Now, the `CH_(3)` group at `beta`-carbon cause steric hindrance to nuclephilic substitution `(S_(N^(2)))`, therefore, `(E_(2))` occurs preferentially to form 2 methylpropene