The formation of complexes between aluminium(III) and two hydroxy-aromatic ligands of possible environmental and biological relevance, 2-hydroxy-phenylethanone (HPE) and 2-hydroxybenzeneacetic acid (HBA), in aqueous 0.6 m (Na)Cl at 25 °C has been investigated by means of potentiometric titrations. In both systems, the formation of two complexes, AlL and AlLH–1, has been observed, and the following stability constants have been evaluated: for HPE (pKa = 10.027 ± 0.004), log (beta)AlL = 7.34 ± 0.01 and log (beta)AlLH–1 = 1.97 ± 0.04; for HBA (pKa1 = 4.116 ± 0.004 and pKa2 = 10.507 ± 0.008), log (beta)AlL = 8.06 ± 0.03 and log (beta)AlLH–1 = 3.11 ± 0.07. The qualitative and quantitative results obtained have been partially confirmed by UV-spectrophotometry and 1H NMR spectroscopy.
Complex formation between aluminium(III) and two hydroxy-aromatic ligands: 2-hydroyphenylethanone and 2-hydroxybenzeneacetic acid.
DI MARCO, VALERIO;TAPPARO, ANDREA;BOMBI, GIUSEPPE GIORGIO
1999
Abstract
The formation of complexes between aluminium(III) and two hydroxy-aromatic ligands of possible environmental and biological relevance, 2-hydroxy-phenylethanone (HPE) and 2-hydroxybenzeneacetic acid (HBA), in aqueous 0.6 m (Na)Cl at 25 °C has been investigated by means of potentiometric titrations. In both systems, the formation of two complexes, AlL and AlLH–1, has been observed, and the following stability constants have been evaluated: for HPE (pKa = 10.027 ± 0.004), log (beta)AlL = 7.34 ± 0.01 and log (beta)AlLH–1 = 1.97 ± 0.04; for HBA (pKa1 = 4.116 ± 0.004 and pKa2 = 10.507 ± 0.008), log (beta)AlL = 8.06 ± 0.03 and log (beta)AlLH–1 = 3.11 ± 0.07. The qualitative and quantitative results obtained have been partially confirmed by UV-spectrophotometry and 1H NMR spectroscopy.
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