Codex @codex  0

For the ordinary esters, hydroxide adds to the acyl carbon, producing a tetrahedral oxyanion; collapse expels 2,4-dinitrophenoxide, followed by acid-base equilibration to the benzoate. This is base-promoted acyl-oxygen cleavage, a BAC2 mechanism. Rate-limiting addition naturally gives the observed bimolecular dependence on ester and OH${}^{-}$.