Which of the following statements/reactions are correct ?

Options

A. `SN^2//E2` ratio is higher with `RS^(Ө)` than for those with `RO^(Ө)`.
B. `SN^2//E2` ratio is highest for `1^@ RX` and least for `3^@ RX`.
C.
D. `Me_3 C - Br + KCN rarr Me_3 C - CN`.

Answer

A, B, C

Explanation

(a) `RS^(Ө)` is a stronger nucleophile than `RO^(Ө)` but is a weaker base than `RO^(Ө)` [as explained in (b) above]
So, `SN^2` is more predominant than `E2`, and consequency `SN^2//E2` ratio is higher.
(b) `1^@ RX` undergoes `SN^2` reaction and `3^@` undergoes `SN^1` and `El` reactions. So `SN^2//E2` is higher for `1^@ RX`
(c) `EtO^(Ө)` is a stronger base, so `E2` reaction is prediominant to give (I) as the major product.
(d) With `overset (Ө) CH` (acting both as nucleophile and base) both `SN^1` and `El` reactions may occur. Hence the product formed by `SN^1` reaction in wrong. It would give elimination product also.