Question

What is the hyperconjugation effect?

Answer 1

1. Hyperconjugation involves the delocalization of $\mathrm{\sigma }$ electrons of the $\mathrm{C}-\mathrm{H}$ bond of an alkyl group that is directly attached to an atom of an unsaturated system or an atom with an unshared p orbital.
2. It is a permanent effect.
3. Hyperconjugation is also known as no bond resonance because there is no direct bond between Carbon and Hydrogen.
4. For example: In Ethyl cation (${\mathrm{CH}}_3{{\mathrm{CH}}_2}^{+}$), The ${\mathrm{sp}}^2$ Carbon of Ethyl cation that has a positive charge has a vacant p orbital, the electrons of Hydrogen shift from ${\mathrm{sp}}^3$Carbon to that ${\mathrm{sp}}^2$Carbon, and thus the formation of a double bond $\mathrm{C}=\mathrm{C}$ occurs.
5. The order of hyperconjugation is as follows.-
   ${\mathrm{CH}}_3^{+}<{\mathrm{CH}}_3{\mathrm{CH}}_2^{+}<{\mathrm{CH}}^{+}{\left({\mathrm{CH}}_3\right)}_2<{\mathrm{C}}^{+}{\left({\mathrm{CH}}_3\right)}_3$
6. Greater the number of alkyl groups attached to the carbon atom, the greater the hyper conjugation.