Kinetic and mechanistic studies on substitution reactions of oxalato ligands from tris(oxalato )chromate (lll) with bis-(2-aminoethyl)-amin-N, N, N', N", N"- pentaacetic acid (DTPA)

Abstract

The kinetics of substitution of oxalato from tris(oxalato) chromate(III) with bis-(2-aminoethyl)-amin- N,N,N',N'',N"-pentaacetic acid (DTPA) has been studied spectrophotometrically in alkaline medium. From the observed dependence of the rate on <i>p</i>H and DTPA concentration a probable mechanism has been suggested for the overall change involving two concurrent paths; corresponding <img src='/image/spc_char/delta.gif' border=0><i>H</i>^† and <img src='/image/spc_char/delta.gif' border=0>S^† values have also been determined. The rates are found to be dependent on ionic strength and independent of nature of different electrolytes.