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Cyclic Voltammetric and Electrochemical Simulation Studies on the Electro-Oxidation of Catechol in the Presence of 4, 4-bipyridine
Tekalign Kasa,
Theodros Solomon
Issue:
Volume 5, Issue 3, June 2016
Pages:
45-55
Received:
21 February 2016
Accepted:
9 March 2016
Published:
16 April 2016
Abstract: The studies were made using cyclic voltammetry on a glassy carbon electrode in aqueous solution containing phosphate buffer solution as supporting electrolyte. The purpose of the investigation was to carry out a quantitative detailed study of the electrochemical oxidation of catechol in the presence of 4, 4-bipyridine in aqueous solution. The electrooxidation of catechol produces a very reactive intermediate, o-benzoquinone, which subsequently reacts with 4, 4-bipyridine in 1, 4-Michael addition reaction to form the corresponding catechol derivative product. The kinetic data were extracted from cyclic voltammograms with the help of digital simulation. The results of the study show that catechol is oxidized in aqueous phosphate buffer solution to a very reactive intermediate o-benzoquinone.
Abstract: The studies were made using cyclic voltammetry on a glassy carbon electrode in aqueous solution containing phosphate buffer solution as supporting electrolyte. The purpose of the investigation was to carry out a quantitative detailed study of the electrochemical oxidation of catechol in the presence of 4, 4-bipyridine in aqueous solution. The elect...
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Ruthenium(III)-Catalyzed Oxidation of Vanillin by Anticancer Hexachloroplatinate(IV) Complex in Perchloric Acid Solutions: A Kinetic Study
Ahmed Fawzy,
Ishaq A. Zaafarany,
Khalid S. Khairou,
Layla S. Almazroai,
Badriah A. Al-Jahdali,
Tahani M. Bawazeer
Issue:
Volume 5, Issue 3, June 2016
Pages:
56-64
Received:
3 April 2016
Accepted:
9 April 2016
Published:
3 May 2016
Abstract: The kinetics of oxidation of vanillin (VAN) by hexachloroplatinate(IV) has been investigated in perchloric acid solutions in the presence of ruthenium(III) catalyst at a constant ionic strength of 1.0 mol dm-3 and at 25°C. The progress of the reaction was followed spectrophotometrically. The reaction was not proceeding in the absence of the catalyst. The reaction exhibited first order kinetics with respect to both [HCP] and [Ru(III)] and less than unit order with respect to both [VAN] and [H+]. Increasing ionic strength and dielectric constant were found to increase the oxidation rate. The reaction mechanism adequately describing the kinetic results has been proposed. Both spectral and kinetic evidences revealed formation of an intermediate complex between vanillin substrate and ruthenium(III) catalyst prior to the rate-determining step. The complex reacts with the oxidant (HCP) by an inner-sphere mechanism leading to decomposition of the complex in the rate-determining step to give rise to the final oxidation products which were identified by both spectral and chemical analyses as vanillic acid and tetrachloroplatinate(II). The rate law expression for the catalyzed reaction was deduced. The reaction constants involved in the different steps of the reaction mechanism have been evaluated. The activation parameters associated with the rate-limiting step of the reaction, along with the thermodynamic quantities of the equilibrium constant have been evaluated and discussed.
Abstract: The kinetics of oxidation of vanillin (VAN) by hexachloroplatinate(IV) has been investigated in perchloric acid solutions in the presence of ruthenium(III) catalyst at a constant ionic strength of 1.0 mol dm-3 and at 25°C. The progress of the reaction was followed spectrophotometrically. The reaction was not proceeding in the absence of the catalys...
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A Comparative Kinetic Study of Silver(I)-Catalyzed Oxidations of Alanine and Valine by Platinum (IV) in Perchloric and Sulfuric Acids Solutions
Ahmed Fawzy,
Ishaq A. Zaafarany,
Fahd A. Tirkistani,
Ismail Althagafi,
Jabir Alfahemi
Issue:
Volume 5, Issue 3, June 2016
Pages:
65-73
Received:
17 April 2016
Accepted:
25 April 2016
Published:
10 May 2016
Abstract: The kinetics of oxidations of two aliphatic α-amino acids (AA), namely, alanine and valine by platinum (IV) has been investigated spectrophotometrically in perchloric and sulfuric acids solutions in the presence of silver (I) catalyst at a constant ionic strength of 1.0 mol dm-3 and at 25°C. The reactions were very slow to be measured in the absence of the catalyst. The reactions in both acids showed a first order dependence on both [PtIV] and [AgI], and less than unit order dependences with respect to both [AA] and [H+]. Increasing ionic strength was found to decrease the oxidation rates. Under comparable experimental conditions, the oxidation rates of alanine and valine in perchloric acid solutions were found to be about five times higher than those obtained in sulfuric acid solutions and the oxidation rates of alanine in both acids were found to be higher than those recorded with respect to valine. A plausible oxidations mechanism has been proposed and the rate law expression has been derived. Both spectral and kinetic evidences revealed formation of 1:1 intermediate complexes between AA and AgI in both acids before the rate-controlling step. Then the formed complexes react with the oxidant (PtIV) by an inner-sphere mechanism to give rise to the oxidation products of the amino acids which were identified as the corresponding aldehyde, ammonium ion and carbon dioxide. The activation parameters of the second order rate constants were evaluated and discussed.
Abstract: The kinetics of oxidations of two aliphatic α-amino acids (AA), namely, alanine and valine by platinum (IV) has been investigated spectrophotometrically in perchloric and sulfuric acids solutions in the presence of silver (I) catalyst at a constant ionic strength of 1.0 mol dm-3 and at 25°C. The reactions were very slow to be measured in the absenc...
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Ionic Liquids: A Review on Greener Chemistry Applications, Quality Ionic Liquid Synthesis and Economical Viability in a Chemical Processes
Issue:
Volume 5, Issue 3, June 2016
Pages:
74-79
Received:
12 April 2016
Accepted:
22 April 2016
Published:
25 May 2016
Abstract: Climate change overshadowing the globe is a vibrant phenomenon now days. Decades have passed since scientists from around the world started informing and forecasting the impact of this threatening climatic condition. It is not only disseminating the likely consequence, but also scientists have been battling to uphold safe environment for the next generation. Politicians have also been making climatic issue discussion on the top of their agenda on different world summit. As has been mentioned several times, this unfortunate environmental feature came in to being by human activity (directly or indirectly) and is believed to be reversed by same creature. This review is intended thinking that safe chemical process (from simple laboratory experiment to huge industrial process), reduced effluent to the environment and minimized cost to the process, which can be brought about by utilization of ionic liquids, could be one of the elements to retard and/or stop this catastrophe. In this regard, an attempt has been made to include the meaning, history, properties and different applications of ionic liquids, the green chemistry.
Abstract: Climate change overshadowing the globe is a vibrant phenomenon now days. Decades have passed since scientists from around the world started informing and forecasting the impact of this threatening climatic condition. It is not only disseminating the likely consequence, but also scientists have been battling to uphold safe environment for the next g...
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