Effect of Transition Metal Ions on the Hydrolysis of the Methyl Derivatives of Salicylanil

Abstract

The catalytic effect of Ni(II), Zn(II) and Cu(II) ions on the hydrolysis

of the methyl derivatives of salicylanil has been studied at pH-4.58 at 35ºC.

The hydrolysis follows the sequence meta > para > ortho in the absence

and presence of metal ions. The presence of metal ions accelerates the

hydrolysis rate according to the sequence Ni(II) > Zn(II) > Cu(II) which

is in accordance with the Irving and Williams order of stability constants

of metal chelates involving nitrogen and oxygen donor ligands. The initial

retardation of rate of hydrolysis observed at lower Cu(II) concentrations

has been explained as due to Jahn-Teller distortion of the metal complex

to achieve stability. A suitable reaction mechanism has been suggested for

the metal ion-catalysed hydrolysis of the imines under study.