Question

Consider thiol anion `(RS^(Θ))` and alkoxy anion `(RO^(Θ))`. Which of the following statement is correct ?
A. `RS^(Θ)` is less basic and less nucleophilic than `RO^(Θ)`
B. `RS^(Θ)` is less basic but more nucleophilic than `RO^(Θ)`
C. `RS^(Θ)` is more basic and more nucleophilic than `RO^(Θ)`
D. `RS^(Θ)` is more basic but less nucleophilic than `RO^(Θ)`

Answer 1

Correct Answer - B
Since O-H bond is stronger than S-H bond, therefore, `RO^(-)` has a greater tendency to accept a proton than `RS^(-)` and hence `RO^(-)` is a stronger base than `RS^(-)`. Conversely, since S is less electro-negative than O, therefore, `RS^(-)` is more willing to donate a pair of electrons than `RO^(-)` and hence `RS^(-)` is more nucleophilic than `RO^(-)`. Thus, option (b) is correct.