In chemistry, a nucleofuge (from nucleo- atomic nucleus and fuge ‘to run away/escape’) is a leaving group which retains the lone pair of electrons from its previous bond with another species.
Nucleofugality: Leaving group tendency.
- Leaving groups that are neutral after departure are better than leaving groups that are charged after departure.
- Among charged leaving groups, resonance stabilized ones are better.
- For a leaving group that is negatively charged after departure, nucleofugality incerases with the capability of retaining the charge.
- In a given period, nucleofugality increases with increase in electronegativity. (Hence, it also increases with increase in -Character.)
- In a given period, nucleofugality increases with increase in atomic volume.
- Nucleofugality increases with the presence of Electron Withdrawing Group.