Question

Which substance in the reaction serves as the electrophile?'?

Answer 1

Electrophiles are reagents attracted to electrons.

Electrophiles tend to be electron-deficient and carry partial positive charges. They are attracted to species with lone pairs of electrons. For example, protons
`\text{H}^+` have no electrons and tend to share ones with other species, hence behaving as electrophiles in aqueous reactions. In the reaction between
`\text{H}^+` and ammonia
`\text{NH}_3`, protons would be attracted to lone electron pairs on nitrogen atoms in ammonia molecules, which carry partial positive charges.

The Lewis Acid-base theory define Acids as species that accept electron pairs in a particular acid-base reaction. Electrophiles, by definition, tend to accept electrons. Lewis acids thus behaves as electrophiles in acid-base reactions. In the previous example,
`\text{H}^+` demonstrates acidic behavior and can be inferred as an electrophile.