16.0 Hyperconjugation

  General Organic Chemistry

A $\sigma -$ bond can stabilise a neighbouring carbocation (or positively charged carbon) by donating electrons to the vacant p-orbital.

The positive charge is delocalized or 'spread out', and this stabilizing effect is known as "no-bond resonance".

Notes:

Number of $\alpha$ hydrogen $ \propto $ Number of hyperconjugating structure $ \propto $ stability $ \propto $ $\frac{1}{{{\text{Heat of hydrogenation}}}}$ $ \propto $ Polarity $ \propto $ dipole moment $ \propto $ $\frac{1}{{{\text{bond length}}}}$

Question: The correct order for the stability among the following compound is,

Solution: For checking the stability of carbocation, the best method is to find out the number of $\alpha$ hydrogens.

Thus the stability is as shown below,