Cargando…

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...

Descripción completa

Detalles Bibliográficos
Autores principales: Zavitsanos, Kimon, Tampouris, Konstantinos, Petrou, Athinoula L.
Formato: Texto
Lenguaje:English
Publicado: Hindawi Publishing Corporation 2008
Materias:
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
_version_ 1782164237703970816
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
work_keys_str_mv AT zavitsanoskimon reactionofchromiumiiiwith34dihydroxybenzoicacidkineticsandmechanisminweakacidicaqueoussolutions
AT tampouriskonstantinos reactionofchromiumiiiwith34dihydroxybenzoicacidkineticsandmechanisminweakacidicaqueoussolutions
AT petrouathinoulal reactionofchromiumiiiwith34dihydroxybenzoicacidkineticsandmechanisminweakacidicaqueoussolutions