Kinetics and Mechanism of the Reaction between Chromium(III) and 2,3-Dihydroxybenzoic Acid in Weak Acidic Aqueous Solutions
The reaction between chromium(III) and 2,3-dihydroxybenzoic acid (2,3-DHBA) takes place in at least three stages, involving various intermediates. The ligand (2,3-DHBA)-to-chromium(III) ratio in the final product of the reaction is 1 : 1. The first stage is suggested to be the reaction of [Cr(H2O)5(...
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| Format: | Article |
| Language: | English |
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Wiley
2010-01-01
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| Series: | Bioinorganic Chemistry and Applications |
| Online Access: | http://dx.doi.org/10.1155/2010/348692 |
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| author | Athinoula L. Petrou Vladimiros Thoma Konstantinos Tampouris |
| author_facet | Athinoula L. Petrou Vladimiros Thoma Konstantinos Tampouris |
| author_sort | Athinoula L. Petrou |
| collection | DOAJ |
| description | The reaction between chromium(III) and 2,3-dihydroxybenzoic acid (2,3-DHBA) takes place in at least three stages, involving various intermediates. The ligand (2,3-DHBA)-to-chromium(III) ratio in the final product of the reaction is 1 : 1. The first stage is suggested to be the reaction of [Cr(H2O)5(OH)]2+ with the ligand in weak acidic aqueous solutions that follows an Id mechanism. The second and third stages do not depend on the concentrations of chromium(III), and their activation parameters are ΔH≠=61.2±3.1 kJmol−1, ΔS≠=−91.1±11.0 JK−1mol−1, ΔH≠=124.5±8.7 kJmol−1, and ΔS≠=95.1±29.0 JK−1mol−1. These two stages are proposed to proceed via associative mechanisms. The positive value of ΔS≠ can be explained by the opening of a four-membered ring (positive entropy change) and the breaking of a hydrogen bond (positive entropy change) at the associative step of the replacement of the carboxyl group by the hydroxyl group at the chromium(III) center (negative entropy change in associative mechanisms). The reactions are accompanied by proton release, as shown by the pH decrease. |
| format | Article |
| id | doaj-art-0d7152b50cd142bdbaeb63a951b42b3d |
| institution | Kabale University |
| issn | 1565-3633 1687-479X |
| language | English |
| publishDate | 2010-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Bioinorganic Chemistry and Applications |
| spelling | doaj-art-0d7152b50cd142bdbaeb63a951b42b3d2025-02-03T06:11:23ZengWileyBioinorganic Chemistry and Applications1565-36331687-479X2010-01-01201010.1155/2010/348692348692Kinetics and Mechanism of the Reaction between Chromium(III) and 2,3-Dihydroxybenzoic Acid in Weak Acidic Aqueous SolutionsAthinoula L. Petrou0Vladimiros Thoma1Konstantinos Tampouris2Laboratory of Inorganic Chemistry, University of Athens, Panepistimioupolis, 15771 Athens, GreeceLaboratory of Inorganic Chemistry, University of Athens, Panepistimioupolis, 15771 Athens, GreeceLaboratory of Inorganic Chemistry, University of Athens, Panepistimioupolis, 15771 Athens, GreeceThe reaction between chromium(III) and 2,3-dihydroxybenzoic acid (2,3-DHBA) takes place in at least three stages, involving various intermediates. The ligand (2,3-DHBA)-to-chromium(III) ratio in the final product of the reaction is 1 : 1. The first stage is suggested to be the reaction of [Cr(H2O)5(OH)]2+ with the ligand in weak acidic aqueous solutions that follows an Id mechanism. The second and third stages do not depend on the concentrations of chromium(III), and their activation parameters are ΔH≠=61.2±3.1 kJmol−1, ΔS≠=−91.1±11.0 JK−1mol−1, ΔH≠=124.5±8.7 kJmol−1, and ΔS≠=95.1±29.0 JK−1mol−1. These two stages are proposed to proceed via associative mechanisms. The positive value of ΔS≠ can be explained by the opening of a four-membered ring (positive entropy change) and the breaking of a hydrogen bond (positive entropy change) at the associative step of the replacement of the carboxyl group by the hydroxyl group at the chromium(III) center (negative entropy change in associative mechanisms). The reactions are accompanied by proton release, as shown by the pH decrease.http://dx.doi.org/10.1155/2010/348692 |
| spellingShingle | Athinoula L. Petrou Vladimiros Thoma Konstantinos Tampouris Kinetics and Mechanism of the Reaction between Chromium(III) and 2,3-Dihydroxybenzoic Acid in Weak Acidic Aqueous Solutions Bioinorganic Chemistry and Applications |
| title | Kinetics and Mechanism of the Reaction between Chromium(III) and 2,3-Dihydroxybenzoic Acid in Weak Acidic Aqueous Solutions |
| title_full | Kinetics and Mechanism of the Reaction between Chromium(III) and 2,3-Dihydroxybenzoic Acid in Weak Acidic Aqueous Solutions |
| title_fullStr | Kinetics and Mechanism of the Reaction between Chromium(III) and 2,3-Dihydroxybenzoic Acid in Weak Acidic Aqueous Solutions |
| title_full_unstemmed | Kinetics and Mechanism of the Reaction between Chromium(III) and 2,3-Dihydroxybenzoic Acid in Weak Acidic Aqueous Solutions |
| title_short | Kinetics and Mechanism of the Reaction between Chromium(III) and 2,3-Dihydroxybenzoic Acid in Weak Acidic Aqueous Solutions |
| title_sort | kinetics and mechanism of the reaction between chromium iii and 2 3 dihydroxybenzoic acid in weak acidic aqueous solutions |
| url | http://dx.doi.org/10.1155/2010/348692 |
| work_keys_str_mv | AT athinoulalpetrou kineticsandmechanismofthereactionbetweenchromiumiiiand23dihydroxybenzoicacidinweakacidicaqueoussolutions AT vladimirosthoma kineticsandmechanismofthereactionbetweenchromiumiiiand23dihydroxybenzoicacidinweakacidicaqueoussolutions AT konstantinostampouris kineticsandmechanismofthereactionbetweenchromiumiiiand23dihydroxybenzoicacidinweakacidicaqueoussolutions |