Abstract: Linear free-energy relationships between the rate constants for hydrolysis and the pK. of the leaving group are obtained for both mono-and dianions of phosphate esters, ROPO (OH) 2. The reactivity of the monoanions depends only weakly on the leaving group, but that of the dianions is nine times more sensitive to the basicity of RO-. Both ionic species are considered to be hydrolyzed by unimolecular mechanisms, involving the elimination of ...