1,721,022 research outputs found
Interaction of Iron(III) with 2-Hydroxybenzohydroxamic Acid in Aqueous Solutions.
No full textThe complex formation between the Fe3+ ion and 2-hydroxybenzohydroxamic acid (salicylhydroxamic acid, H2L) has been studied at 25 C in 1.0 mol •dm-3 (Na)ClO4 medium by potentiometric titrations with redox Fe3+/Fe2+ and/or glass electrodes. On account of precipitation of Fe(II)-salicylhydroxamates, the redox half-cell was employed only in measuremenrts at [H+] > 3 • 10-3 mol •dm-3. The redox and glass electrode data, collected in the concentration ranges (mol •dm-3) 1• 10-3 e [Fe(III)] e 5 • 10-3, 0 < [H2L]tot e 0.015, and 0.1 g [H+] g 10-2, are consistent with the presence of the species FeHL2+ and Fe(HL)2 +. Glass electrode measurements, in solutions where (10-1.5 g [H+] g 10-4) mol •dm-3, (3• 10-4 e [Fe(III)] e 7 • 10-3) mol •dm-3, and (1 e [H2L]tot/[Fe(III)] e 3) mol •dm-3, are explained by assuming in addition to FeHL2+ and Fe(HL)2 + the complexes FeL2 - and Fe5(HL)5(OH)8 2+. The pentamer is probably a derivative of the hypothetical hydrolytic complex, Fe5(OH)8 7+. Stability constants for their formation in 1 M NaClO4 as well as in dilute solution are reported
The stability of Cu(II), Ni(II), and U(VI) complexes with 2-hydroxybenzohydroxamic acid in aqueous solutions
No full textBehavior of glutathione as ligand of lead (II)
Full text linkThe presence and mobilization of toxic metal cations represents under many aspects a current and
important problem in the environmental field. In this research, as cation lead (II) ion was studied. The
formation of complexes between glutathione and lead (II) was studied at 25 C and in 1.00 M NaCl as
ionic medium by means of measurements of electromotive force (e.m.f.) of cells containing glass and lead
amalgam electrodes. In the same experimental conditions, the protonation constants of glutathione were
determined potentiometrically, using a cell containing the glass electrode. In the same experimental
conditions, by considering glutathione (GSH) completely deprotonated, four protonation constants were
determined.
Potentiometric data could be explained by assuming the formation of 1:1 complexes between GSH and
Pb2þ and with the participation of hydrogen ions. The stability constants of the assumed complexes were
determined. The 1:1 ratio between GSH and lead (II) was confirmed by spectrophotometric
investigations.
Measurements by Infrared Rays (IR) and protonic Nuclear Magnetic Resonance (1H NMR) provide
information on the structure of the found complexes
The stability of dioxouranium(VI)-2-hydroxybenzohydroxamic acid complexes in acqueous solutions.
No full textThe acidic costants of 2-hydroxybenzohydroxamic acid in NaClO4 solutions at 25°C.
No full textThe protolysis equilibria of 2-hydroxybenzohydroxamic acid, H(2)SAX, have been studied at 25degreesC in different ionic media by potentiometric titration with a glass electrode. The media were 0.513, 1.05, 2.21 and 3.5 mol/kg NaClO4. The constants beta(-p)(H(2)SAXreversible arrowH(2-p)SAX(-p)+pH(+)), combined with salting effects of NaClO4 on H(2)SAX deduced from solubility determinations, were processed by the specific interaction theory, SIT, to give equilibrium constants at infinite dilution, log beta(-1)degrees = -7.655+/-0.013 and log beta(-2)degrees = -1 7.94+/-0.04, as well as specific interaction coefficients b(HSAX(-),Na+) = 0.12+/-0.01 and b(SAX(2-),Na+) = 0.17+/-0.02, molal(-1)
- …
