Intramolecular catalysis and the rate‐determining step in the alkaline hydrolysis of ethyl salicylate

摘要: The alkaline hydrolysis of ethyl salicylate has been studied at 35°C within the [ŌH] range 0.001–2.00 M. observed hydroxide ion concentration dependence rate explained by proposing occurrence two parallel kinetic steps shown as in law: = k1[H2O] [ES] + k2[ŌH] where ES− represents ionized salicylate. value k1, is ca. 106 times larger than expected constant for uncatalyzed aqueous cleavage ethyl-p-hydroxybenzoate. This advantage attributed to intramolecular general base catalysis. analysis activation parameters indicates that enhancement entirely due favorable entropy change. Bronsted-type plots show an extremely low sensitivity constants k1 and k2 with respective Bronsted coefficient β −0.03 ± 0.01 −0.01 0.05, on basicity leaving groups esters (alkoxide phenoxide ions). values these coefficients indicate essentially little or insignificant amount bond between carbonyl carbon group rate-determining step both steps. obtained different ethanol follow Grunwald-Winstein mY equation m 0.14 0.01.