15.1.4—Elimination reaction with NaOH in ethanol

In elimination, a base removes H from a carbon next to the C–X carbon while X⁻ leaves, forming a C=C. Hot ethanolic NaOH favours elimination of a halogenoalkane.

The solvent and temperature matter: aqueous hydroxide more often gives substitution, while ethanolic hydroxide and heat favour elimination. Balance atoms and identify the small molecules removed.

CH₃CH₂Br + OH⁻(ethanol) → CH₂=CH₂ + H₂O + Br⁻. The product is an alkene, not an alcohol.

Do not use the aqueous substitution equation under ethanolic conditions, and do not call elimination an addition reaction.