The oxidation of ferrous ions by dissolved oxygen in aqueous solutions in the presence of such chelating agents as EDTA, DTPA, EDTAOH, EDTP, CyDTA and NTA was studied spectrophotometrically. The rate equation for the oxidation reaction is:
d[Fe^III]/dt=4k_p[Fe^IIHZ][O_2]+4k_n[Fe^IIZ][O_2]
where kp is the rate constant for the (1) reaction; kn, the rate constant for the (2) reaction; FeIIHZ, protonated chelate, and FeIIZ, the normal chelate.
&Fe^IIHZ+O_2\xrightarrowk_pFe^IIIZ+HO_2 \labeleq1
&Fe^IIZ+O_2\xrightarrowk_nFe^IIIZ+O_2^-\labeleq2
The linear relationship between log k and log Rf shown by Eq. (3), was obtained from all the experimental results except for those on the EDTPA and CyDTA systems:
logk=0.92+0.13logR_f\labeleq3
In Eq. (3), k is 4kp and Rf is KFeIIIL⁄KFeIIHL, for the protonated chelate, while k is 4kn and Rf is KFeIIIL⁄KFeIIL for the normal chelate. In the cases of the DTPA and CyDTA systems, a deviation from the straight line was observed. This can be explained by steric hindrance of the oxygen attack by these chelates.
Aromatic amines, such as p-phenylenediamine (PD) or p-aminophenol (AP) have been found to polymerize oxidatively at room temperature, catalyzed by ferric chelates, e.g., the Fe(II1)-salt of ethylenediaminetetraacetic acid, in aqueous solution.The polymers from PD or AP are black and do not melt below 30OoC. They have paramagnetic and electroconductive properties (ca. 10 10 0-' .ern-1).They have also reversible oxidation and reduction properties; in methanolic sohltion the polymer is reduced by an aqueous sodium hydrosulfite solution, resulting a light yellow solution, which is re-oxidized by air to the original black polymer. The structures of the polymers are also presented.
ZUSAMMENFASSUNG:Es wurde gefunden, daI3 aromatische Amine wie p-Phenylendiamin (PD) oder p-Aminophenol (AP) bei Zimmertemperatur mit Ferrichelatverbindungen als Katalysator, z. B.dem Fe(II1)-Salz der Athylendiamintetraessigsaure, in waI3riger Losung oxydativ polymerisiert werden.Die Polymeren von PD und A P sind schwarz und schmelzen nicht unter 30OoC. Sie haben paramagnetische Eigenschaften und besitzen eine elektrische Leitfahigkeit von ca. 10-10 a-1. cm-1. Sie sind reversibel reduzierbar ; die methanolikhe Losung des Polymeren wird durch Natriumhyposulfit reduziert und farbt sich rasch schwach gelb. Die reduzierte Losung kann mit Luft oxydiert werden, wobei sieh das schwarze Ausgangspolymere zuriickbildet. Die Strukturen der Polymeren werden angegeben.
Water‐soluble cobalt(III) chelates having a polymeric ligand such as cis‐[Co(en)2‐PVPCl]Cl2 and cis‐[Co‐(trien)PVPCl]Cl2 (PVP = poly‐4‐vinylpyridine) were prepared by substitution reactions between cobalt(III) chelate and PVP in water–alcohol solution. PVP of different degrees of polymerization was used as the ligand in preparation of these complexes. The PVP complexes were identified and their properties ascertained by microanalysis and by a study of the infrared, ultraviolet, visible, and PMR spectra. Most of the characteristic properties of these complexes may be ascribed to the polymeric structure of the PVP ligand.
The interactions of tris(2,2′-bipyridine)ruthenium(II)([Ru(bpy)3]2+) with some polyanions have been studied by means of cation-exchange resins and the luminescence of [Ru(bpy)3]2+. In an aqueous solution of [Ru(bpy)3]2+ in the presence of sodium poly(p-styrenesulfonate)(PSS), the adsorbability of [Ru(bpy)3]2+ on the cation-exchange resins is strongly suppressed by the binding of [Ru(bpy)3]2+ to the polyanion. The relative luminescence intensity of [Ru(bpy)3]2+ in an aqueous solution is enhanced by the addition of PSS. With the addition of sodium chloride to an [Ru(bpy)3]2+/PSS solution, the interaction is impeded by the shielding of the electrostatic potential in the polymer domains by the counter ions. A cooperative interaction between PSS and [Ru(bpy)3]2+ is postulated with a view to accounting for the results. A chemical application of the interaction is demonstrated.
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