Kinetics and mechanism of exchange reaction of [Y(APTA)] (APTA=o-aminophenol-N, N, O-triacetic acid) with copper(II)

Abstract

The kinetics of the exchange reaction between [Y(APTA)] and CuII have been investigated over a range of [H+] from 2.5×10−5 to 7.5×10−4 mol dm−3 at 30°C and ionic strength 0.2 mol dm−3 KNO3. The results show that the exchange reaction proceeds via both self-and proton-catalyzed dissociation of [Y(APTA)] and also by the direct attack of CuII on [Y(APTA)]. The corresponding rate constants kd, kh and kCu have been evaluated as 6.3s−1, 8.4×104 mol−1 dm3 s−1 and 416mol−3 dm3 s−1 respectively. The possible intermediates are discussed in terms of the structure of APTA. The complex-formation rate constants of YIII with APTA3- and HAPTA2- were also obtained.