Question

I. Which of the following solvents is the reaction faster?

II. Indicate `SN^(-1)` or `SN^(2)`.

Answer 1

I. a. `SN^(2) (I^(@) RX)` neutral `Nu^(o-)`, the reaction is faster in more polar solvent containing `80% H_(2)O` and `20% MeOH`.
b. `SN^(-1)` is faster in more polar solvent, `MeOH`
b. `SN^(-1)` is faster in more polar solvent, `MeOH` with negative nucleopphile `(3^(@) RX)`
c. `SN^(2)` negative nucleopphile, faster in less polar solvent pure `MeOH (I^(@) RX)`.
d. `SN^(2)` negative nucleophile faster in aprotic solvent, i.e., `DMSO (1^(@) RX)`
II. a. Leaving group on `C` atom, hence `SN^(2)`.
b. Leaving group on `3^(@) C` atom, `SN^(-1)`.
c. Leaving group on `2^(@)C` atom, `H_(2)O` is not a good nuclophile, and solvent is polar `(:. SN^(-1))`.
d. Leaving grop on `2^(@) C` atom, strong `Nu^(o-)` aprotie solvent, hence `SN^(2)`.
e. Unhindered substrate (less hindred than `1^(@) C`) hence `SN^(2)`.
f. Allylic substrate strong `Nu^(o-)` polar solvents `implies SN^(-1)`.
g. Allylic substate, strong `Nu^(o-)` protic solvents `implies SN^(2)`.
h. Secondary benylic substrate, weak `Nu^(o-)`, polar solvent `implies SN^(-1)`.