Question

Is ${\mathrm{SO}}_3$ an electrophile?

Answer 1

1. Electrophile: Electrophile means electron lover species. More precisely we can say that electrophile is electron-deficient species that can attract electron-rich species.
2. ${\mathrm{SO}}_3$ is a polar molecule with a positive charge on the sulfur atom.
3. It can attract the ring electron.

Hence, ${\mathrm{SO}}_3$ is an electrophile.