 Electron-withdrawing group

A substituent that reduces electron density in a specified molecular region by induction or chemical resonance. The sign and size of its effect depend on connectivity and the measured property.

An electron-withdrawing group (EWG) is a functional group in a molecule that attracts electrons towards itself, effectively pulling electron density away from the rest of the molecule. This can influence the molecule’s reactivity, stability, and overall behavior in chemical reactions. EWGs typically have electronegative atoms or groups that stabilize negative charges or partial positive charges, which can affect mechanisms and outcomes in reactions.