Phenol-amide chelates of cobalt(II), nickel(II), copper(II) and zinc(II) as catalysts for hydrolysis of active esters. Part II^a. Kinetics and mechanism of hydrolysis of 4-nitrophenylacetate by the metal(II) chelates of 1,2-bis(2-hydroxybenzamido)ethane and 1 ,3-bis(2-hydroxybenzamido)propane

1228-1232The hydrolysis of 4-nitrophenyl acetate (PNPA) has been studied using mononuclear chelates (ML) of cobalt (II), nickel(II), copper(II) and zinc(II) with 1,2-bis(2-hydroxybenzamido)ethane( L1) and 1,3-bis(2-hydroxybenzamido)-propane(L2) at 26.5± 0.2°C, 1=0.5 mol dm-3, 8.1≤ pH ≤ 9.4 (tris buffer), 0.25 ≤103[ML]T/mol dm-3 ≤3.0.and 35.0% MeOH + water. The ionized species [M(L-H)]- (due to metal ion promoted amide deprotonation) are found to be reactive species for catalysis of PNPA hydrolysis