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The kinetics and mechanism of ligand substitution reactions of nitrilotriacetatoiron(Ⅲ), [Fe(NTA)], and N-(2-hydroxyethyl)-ethylenediaminetfiacetatoiron(Ⅲ), [Fe(HEDTA)], complexes with 4-(2-pyridylazo) resorcinol (Par) has been investigated at pH = 9.0±0.02, I= 0.1mol·1~(-1) (NaClO_4), and temp. = 25 ±0.1℃ and 30±0.1℃ respectively. The reaction has been studied spectrophotometrically at 496 nm. (λ_(max) of Fe(Par)_2). In both reactions the final product was [Fe(Par)_2]~-. The values of second order rate constants for NTA and HEDTA exchange reactions are (10.0±0.8)×10~1·mol~(-1)·s~(-1) and (2.7± 0.1)×10~(-1) 1·mol~(-1)·s~(-1) respectively. The reactions of NTA and HEDTA exchange were studied in the pH range 6-9.5 and 7-10.85 respectively. The rate of reacton of [Fe(NTA)] with HPar~- first increases with pH and then levels off. However, in the case of [Fe(HEDTA)] reaction, the rate increases monotonically with increase of pH in the specified range. The reverse reactions between [Fe(Par)_2
The kinetics and mechanism of ligand substitution reactions of nitrilotriacetatoiron (III), [Fe (NTA)], and N- (2- hydroxyethyl) -ethylenediaminetfiacetatoiron (III) ) resorcinol (Par) has been investigated at pH = 9.0 ± 0.02, I = 0.1mol · 1 -1 (NaClO_4), and temp = 25 ± 0.1 ℃ and 30 ± 0.1 ℃ respectively. The reaction has been studied (λ_ (max) of Fe (Par) _2). In both reactions the final product was [Fe (Par) _2] ~. The values of second order rate constants for NTA and HEDTA exchange reactions are ( 10.0 ± 0.8 × 10-1 mol -1 s -1 and 2.7 ± 0.1 × 10 -1 mol -1 -1 s -1, respectively. The reactions of NTA and HEDTA exchange were studied in the pH range 6-9.5 and 7-10.85 respectively. The rate of reacton of [Fe (NTA)] with HPar ~ - first increases with pH and then levels off. However, in the case of [Fe (HEDTA)] reaction, the rate increases monotonically with increase of pH in the specified range. The reverse reacti ons between [Fe (Par) _2