Kinetics and Mechanism of Oxidation of Catechol by Oxygenated [Co2(O2)(NH3)10]5+ Complex
Nathaniel Oladunni,
Suleiman Ola Idris,
Ameh David Onu,
Gideon Adamu Shallangwa
Issue:
Volume 2, Issue 1, March 2021
Pages:
1-7
Received:
25 November 2020
Accepted:
28 December 2020
Published:
10 February 2021
DOI:
10.11648/j.sf.20210201.11
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Abstract: The kinetics and mechanisms of the redox reaction of Catechol and μ-superoxo-bis[pentaamminecobalt(III)] pentachloridemonohydrate, [(NH3)5Co(O2)Co(NH3)5]Cl5.H2O, hereafter represented as CoO2Co5+ was studied in aqueous perchloric acid under pseudo-first-order conditions at 27±1°C, I=0.35mol dm-3 (NaClO4) and λmax=660nm. μ-superoxo-bis[pentaamminecobalt(III)] pentachloridemonohydrate was used as the oxidant and it was synthesized and characterized according to reported procedure. This study was aimed at generating kinetic data with respect to the oxidation of cathecol by µ-superoxo-bridged binuclear cobalt(III) complex of ammine and to propose plausible mechanism that underpin this reaction of interest. Effect of changes in acid concentration, ionic strength, dielectric constant and temperature on the reaction rate was investigated. The reaction was found to be first-order in both reactants, second-order overall, acid dependent and showed a negative Brønsted-Debye salt effect. Decreasing the dielectric constant from 80.1–74.01 (CH3COCH3/H2O) increased the rate of reaction. A large negative value of ΔS≠ (−224Jmol−1K−1) was obtained during the thermodynamic studies and that showed that the activated complex formed is more ordered. This confirmed that the reaction proceeded by associative mechanism. There was evidence for the presence of free radicals during the course of the reaction, but non to validate the formation of an intermediate complex. In overall, the results suggest an outer-sphere mechanism for the reaction. A probable mechanism is proposed.
Abstract: The kinetics and mechanisms of the redox reaction of Catechol and μ-superoxo-bis[pentaamminecobalt(III)] pentachloridemonohydrate, [(NH3)5Co(O2)Co(NH3)5]Cl5.H2O, hereafter represented as CoO2Co5+ was studied in aqueous perchloric acid under pseudo-first-order conditions at 27±1°C, I=0.35mol dm-3 (NaClO4) and λmax=660nm. μ-superoxo-bis[pentaammineco...
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Nutrient Components and Relation with Resistance Potential of Field Pea Genotypes Seeds to ‘Callosobruchus chinensis L.’ Under Laboratory Conditions
Deressa Tesfaye,
Dugasa Gerenfes
Issue:
Volume 2, Issue 1, March 2021
Pages:
8-16
Received:
31 March 2021
Accepted:
25 May 2021
Published:
31 May 2021
DOI:
10.11648/j.sf.20210201.12
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Abstract: Field pea (Pisum sativum L.) is among the major food crops grown globally for its high protein content. However there is no detailed nutrient composition profile and recently challenged with a storage pest, Callosobruchus chinensis L. This study was carried out to know the nutrient composition and quantify the damage caused by the pest and identify the sources of resistance in the genotypes in Ethiopia. The study was conducted at Kulumsa Agricultural Research Center (KARC) in Ethiopia, during 2019. Nutrients were estimated in laboratory analysis and callosobruchus chinensis L. was used to challenge 26 field pea genotypes under no choice condition, in the laboratory. Results showed a significant differences (p<0.01) in all measured traits. However, the highest nutrient composition and less susceptibility values were recorded by the Pisum var. abyssinicum landraces (collections) number 1 to 10 those are mostly grey and grey/green seed color while the lowest nutrient composition and highest susceptibility values were obtained from the pisum sativum L. those are improved, introduced and crossed genotypes number 11 to 26 with white, creamy, dun, light green, mottled and brown. Within this fpcoll-30/07 had the lowest SI (4.06), followed by fpcoll-42/07 (4.47), fpcoll-2/07 (4.77) and fpcoll-31/07 (4.94) whereas Burkitu, Tegegnech and PDFPT P-313 MILKY had the highest SI (>10) (Table 4). Genotypes; fpcoll-1/07, fpcoll-2/07, fpcoll-28/07, fpcoll-29/07, fpcoll-30/07, fpcoll-31/07, fpcoll-40/07, fpcoll-41/07, fpcoll-42/07/ had high values (ppm) for; ca, k, mg, and zn, whereas all improved, introduced crossed line of considered field peal genotypes had low values (ppm) for the above nutrients. In general there is a possibility that promising field pea genotypes in both high nutrient composition and less susceptibility could be used in a future breeding system.
Abstract: Field pea (Pisum sativum L.) is among the major food crops grown globally for its high protein content. However there is no detailed nutrient composition profile and recently challenged with a storage pest, Callosobruchus chinensis L. This study was carried out to know the nutrient composition and quantify the damage caused by the pest and identify...
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