The hyperconjugative stabilities of tert-butyl cation and `2`-butane, respectively, are due to

Options

A. `sigma` to `p`(empty) and `sigma` to `pi^(**)` electron delocalisations
B. `sigma` to `sigma^(**)` and `sigma` to `pi` electron delocalisations
C. `sigma` to `p` (filled) and `sigma` to `pi` electron delocalisations
D. `p`(filled) to `sigma^(**)` and `sigma` to `pi^(**)` electron delocalisations

Answer

A

Explanation

In tert butyl cation, carbon bearing positive charge has one vacant `p`-orbital hence it is `sigma-p` (empty) conjugation or hyperconjugation.

In `2`-butane, hyperconjugation is between `sigma-pi^(**)` bond.