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Reaction of Chromium(III) with 3,4-Dihydroxybenzoic Acid: Kinetics and Mechanism in Weak Acidic Aqueous Solutions
The interactions between chromium(III) and 3,4-dihydroxybenzoic acid (3,4-DHBA) were studied resulting in the formation of oxygen-bonded complexes upon substitution of water molecules in the chromium(III) coordination sphere. The experimental results show that the reaction takes place in at least th...
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Formato: | Texto |
Lenguaje: | English |
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Hindawi Publishing Corporation
2008
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2635946/ https://www.ncbi.nlm.nih.gov/pubmed/19223961 http://dx.doi.org/10.1155/2008/212461 |
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author | Zavitsanos, Kimon Tampouris, Konstantinos Petrou, Athinoula L. |
author_facet | Zavitsanos, Kimon Tampouris, Konstantinos Petrou, Athinoula L. |
author_sort | Zavitsanos, Kimon |
collection | PubMed |
description | The interactions between chromium(III) and 3,4-dihydroxybenzoic acid (3,4-DHBA) were studied resulting in the formation of oxygen-bonded complexes upon substitution of water molecules in the chromium(III) coordination sphere. The experimental results show that the reaction takes place in at least three stages, involving various intermediates. The first stage was found to be linearly dependent on ligand concentration k (1(obs))′ = k (0) + k (1(obs))[3, 4-DHBA], and the corresponding activation parameters were calculated as follows: ΔH (1(obs)) (≠) = 51.2 ± 11.5 kJ mol(−1), ΔS (1(obs)) (≠) = −97.3 ± 28.9 J mol(−1) K(−1) (composite activation parameters) . The second and third stages, which are kinetically indistinguishable, do not depend on the concentrations of ligand and chromium(III), accounting for isomerization and chelation processes, respectively. The corresponding activation parameters are ΔH (2(obs)) (≠) = 44.5 ± 5.0 kJ mol(−1), ΔS (2(obs)) (≠) = −175.8 ± 70.3 J mol(−1) K(−1). The observed stages are proposed to proceed via interchange dissociative (I (d), first stage) and associative (second and third stages) mechanisms. The reactions are accompanied by proton release, as is shown by the pH decrease. |
format | Text |
id | pubmed-2635946 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2008 |
publisher | Hindawi Publishing Corporation |
record_format | MEDLINE/PubMed |
spelling | pubmed-26359462009-02-17 Reaction of Chromium(III) with 3,4-Dihydroxybenzoic Acid: Kinetics and Mechanism in Weak Acidic Aqueous Solutions Zavitsanos, Kimon Tampouris, Konstantinos Petrou, Athinoula L. Bioinorg Chem Appl Research Article The interactions between chromium(III) and 3,4-dihydroxybenzoic acid (3,4-DHBA) were studied resulting in the formation of oxygen-bonded complexes upon substitution of water molecules in the chromium(III) coordination sphere. The experimental results show that the reaction takes place in at least three stages, involving various intermediates. The first stage was found to be linearly dependent on ligand concentration k (1(obs))′ = k (0) + k (1(obs))[3, 4-DHBA], and the corresponding activation parameters were calculated as follows: ΔH (1(obs)) (≠) = 51.2 ± 11.5 kJ mol(−1), ΔS (1(obs)) (≠) = −97.3 ± 28.9 J mol(−1) K(−1) (composite activation parameters) . The second and third stages, which are kinetically indistinguishable, do not depend on the concentrations of ligand and chromium(III), accounting for isomerization and chelation processes, respectively. The corresponding activation parameters are ΔH (2(obs)) (≠) = 44.5 ± 5.0 kJ mol(−1), ΔS (2(obs)) (≠) = −175.8 ± 70.3 J mol(−1) K(−1). The observed stages are proposed to proceed via interchange dissociative (I (d), first stage) and associative (second and third stages) mechanisms. The reactions are accompanied by proton release, as is shown by the pH decrease. Hindawi Publishing Corporation 2008 2009-02-04 /pmc/articles/PMC2635946/ /pubmed/19223961 http://dx.doi.org/10.1155/2008/212461 Text en Copyright © 2008 Kimon Zavitsanos et al. https://creativecommons.org/licenses/by/3.0/ This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Research Article Zavitsanos, Kimon Tampouris, Konstantinos Petrou, Athinoula L. Reaction of Chromium(III) with 3,4-Dihydroxybenzoic Acid: Kinetics and Mechanism in Weak Acidic Aqueous Solutions |
title | Reaction of Chromium(III) with 3,4-Dihydroxybenzoic Acid: Kinetics and Mechanism in Weak Acidic Aqueous Solutions |
title_full | Reaction of Chromium(III) with 3,4-Dihydroxybenzoic Acid: Kinetics and Mechanism in Weak Acidic Aqueous Solutions |
title_fullStr | Reaction of Chromium(III) with 3,4-Dihydroxybenzoic Acid: Kinetics and Mechanism in Weak Acidic Aqueous Solutions |
title_full_unstemmed | Reaction of Chromium(III) with 3,4-Dihydroxybenzoic Acid: Kinetics and Mechanism in Weak Acidic Aqueous Solutions |
title_short | Reaction of Chromium(III) with 3,4-Dihydroxybenzoic Acid: Kinetics and Mechanism in Weak Acidic Aqueous Solutions |
title_sort | reaction of chromium(iii) with 3,4-dihydroxybenzoic acid: kinetics and mechanism in weak acidic aqueous solutions |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2635946/ https://www.ncbi.nlm.nih.gov/pubmed/19223961 http://dx.doi.org/10.1155/2008/212461 |
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