scholarly journals Cooxidation of Dibenzalacetone with Oxalic Acid by Pyrazinium Chlorochromate

2020 ◽  
Vol 85 ◽  
pp. 1-14
Author(s):  
Seplapatty Kalimuthu Periyasamy ◽  
R. Ponmadasamy
Keyword(s):  
Free Radical ◽  
Ionic Strength ◽  
Oxalic Acid ◽  
Reaction Rate ◽  
Radical Reaction ◽  
Ion Concentration ◽  
Effect Of Temperature ◽  
Radical Mechanism ◽  
Free Radical Reaction ◽  
Hydrogen Ion Concentration

Oxidation of dibenzalacetone with pyrazinium chlorochromate in presence of oxalic acid has been studied at 313 K. Various reaction parameters such as effect of varying oxidant, substrate, Hydrogen ion concentration, catalyst, solvent composition, ionic strength, effect of Mn2+, effect of Al3+ and effect of temperature were studied to determine the kinetics of the reaction. Our study revealed that the reaction followed first order dependence with respect to oxidant and catalyst. The reaction followed fractional order kinetics with respect to substrate and H+. Increase in ionic strength was found to have no effect on the reaction rate and decrease in the dielectric constant of the medium decreases the reaction rate. Increase in the concentration of manganous sulphate retarded the reaction rate which confirmed the two-electron transfer involved in the mechanism. There was no possibility of free radical mechanism, which was confirmed by the addition of acrylonitrile shows no significant effect on the reaction rate indicating the non-involvement of free radical reaction.. Based on the experimental observations a mechanism and rate law has been derived. Moreover, the oxidation product was found to be chalcone epoxide, which was characterized by IR spectrum.

The Effect of Nisin on the Physiology of Bifidobacterium thermophilum

2001 ◽  
Vol 64 (8) ◽  
pp. 1206-1210 ◽  
Author(s):  
EVA KOT ◽  
YANAL MURAD ◽  
ANATOLY BEZKOROVAINY
Keyword(s):  
Free Radical ◽  
Reaction Rate ◽  
Radical Reaction ◽  
Lactate Production ◽  
Free Radical Reaction ◽  
Bifidobacterium Breve ◽  
Yeast Extract Medium ◽  
Bifidobacterium Thermophilum ◽  
Extract Medium ◽  
Rates Of Growth

The effects of nisin on lactate accumulation, growth, and Fe(III) binding by Bifidobacterium thermophilum (ATCC 25866) and Bifidobacterium breve (ATCC 15700) were investigated. Nisin inhibited lactate production by B. thermophilum at concentrations of less than 1 μg/ml, but this effect could be largely eliminated by pretreatment of the organism with 100 to 400 μM Al(III) or La(III). Nisin also inhibited the growth of B. thermophilum at concentrations of 2 to 3 μg/ml, with lower concentrations showing lag periods and/or slower rates of growth. However, Al(III) could not negate these effects, most likely because of Al(III) chelation by the trypticase-proteose-yeast extract medium. Nisin was able to increase instantaneous Fe(III) binding by both B. thermophilum and B. breve, though prolonged-time experiments (up to 120 min) with B. thermophilum indicated no difference in total Fe(III) bound. Nisin was thus able to increase the free radical reaction rate with bifidobacteria and the resultant rate of Fe(III) binding. It was concluded that nisin will normally inhibit the metabolic activity of B. thermophilum along with that of certain bacterial pathogens; however, this effect may in some instances, be abated by a pretreatment with Al(III). Moreover, by accelerating free radical action and the binding of iron by bifidobacteria, nisin may be able to potentiate their normal probiotic action.

scholarly journals Kinetics Mechanism and Thermodynamic Study of the Oxidation of Iodide Ion by Dichromate Ion in Acidic Medium

2020 ◽  
Vol 24 (5) ◽  
pp. 821-826
Author(s):  
B.E. Nyong ◽  
F.E. Abeng ◽  
O.A. Ushie ◽  
B.J. Bassey ◽  
M.M. Edim
Keyword(s):  
Ionic Strength ◽  
Thermodynamic Parameters ◽  
Redox Reaction ◽  
Acidic Medium ◽  
Kinetic Mechanism ◽  
Thermodynamic Study ◽  
Ion Concentration ◽  
Effect Of Temperature ◽  
Hydrogen Ion Concentration ◽  
Iodide Ion

This work introduces a newly developed kinetic mechanism and thermodynamic study that gives a clear theoretical insight between the iodine and chromium in acid solution. The paper mainly focuses on evaluating kinetic mechanism and thermodynamic properties of the oxidation of iodide by dichromate ion in acidic medium. This study was investigated using iodometric method. The rate has been studied by appropriate choice of concentrated conditions at constant temperature and ionic strength. The kinetic studies revealed half order reaction with respect to dichromate ion, first order for iodide ion and second order for hydrogen ion concentration. The dependence of reaction rate on the temperature was monitored in order to generate some thermodynamic parameters, which can be used in predicting the direction and spontaneity of the reaction. The thermodynamic studies of this reaction revealed negative values for ΔG, ΔS and positive values for ΔH which is an indication that the reaction wasspontaneous and endothermic. The oxidant chromium (vi) exist in acidic media as H2CrO4. The effect of ionic strength on the rate of redox reaction was investigated. The ionic strength was adjusted by varying the concentration of the nitrate to maximum. The effect of temperature was also studied to evaluate the thermodynamic parameters. Transition metals should be use as catalyst for future purpose to monitor the rate of redox reaction. The techniques employed on this research are very useful in determining the rate of a redox reaction. Keywords: Kinetic, thermodynamic, oxidation, iodometric method

Kinetics of the Production of Castor Oil Maleate through the Autocatalyzed Thermal Reaction and the Free Radical Reaction

2017 ◽  
Vol 50 (2) ◽  
pp. 112-121 ◽  
Author(s):  
Dayanne L. H. Maia ◽  
Elenilson G. Alves Filho ◽  
Antonino F. Barros Junior ◽  
Fabiano A. N. Fernandes
Keyword(s):  
Free Radical ◽  
Castor Oil ◽  
Radical Reaction ◽  
Thermal Reaction ◽  
Free Radical Reaction ◽  
Kinetics Of

Manganese(III)-based oxidative free-radical reaction of α-allyl-β-keto ester with molecular oxygen

1993 ◽  
Vol 34 (52) ◽  
pp. 8509-8512 ◽  
Author(s):  
Takashi Ohshima ◽  
Mikiko Sodeoka ◽  
Masakatsu Shibasaki
Keyword(s):  
Free Radical ◽  
Molecular Oxygen ◽  
Radical Reaction ◽  
Free Radical Reaction ◽  
Keto Ester

scholarly journals Gasification Pathways and Reaction Mechanisms of Primary Alcohols in Supercritical Water

2019 ◽  
Author(s):  
Brian Pinkard ◽  
John Kramlich ◽  
Igor V. Novosselov
Keyword(s):  
Free Radical ◽  
Supercritical Water ◽  
Reaction Mechanisms ◽  
Radical Reaction ◽  
Water Environment ◽  
Waste To Energy ◽  
Reaction Pathways ◽  
Free Radical Reaction ◽  
Reaction Products ◽  
Primary Alcohols

<div> <p></p><p>Supercritical water gasification is a promising waste-to-energy technology with the ability to convert aqueous and/or heterogeneous organic feedstocks to high-value gaseous products. Reaction behavior of complex molecules in supercritical water can be inferred through knowledge of the reaction pathways of model compounds in supercritical water. In this study methanol, ethanol, and isopropyl alcohol are gasified in a continuous supercritical water reactor at temperatures between 500 and 560 °C, and for residence times between 3 and 8 s. <i>In situ</i> Raman spectroscopy is used to rapidly identify and quantify reaction products. The results suggest the dominance of chain-branching, free radical reaction mechanisms that are responsible for decomposing primary alcohols in the supercritical water environment. The presence of a catalytic surface is proposed to be highly significant for initiating radical reactions. Global reaction pathways are proposed, and mechanisms for free radical reaction initiation, propagation, and termination are discussed in light of these and previously published experimental results.</p><br><p></p></div>

scholarly journals Gasification Pathways and Reaction Mechanisms of Primary Alcohols in Supercritical Water

2019 ◽  
Author(s):  
Brian Pinkard ◽  
John Kramlich ◽  
Igor V. Novosselov
Keyword(s):  
Free Radical ◽  
Supercritical Water ◽  
Reaction Mechanisms ◽  
Radical Reaction ◽  
Water Environment ◽  
Waste To Energy ◽  
Reaction Pathways ◽  
Free Radical Reaction ◽  
Reaction Products ◽  
Primary Alcohols

<div> <p></p><p>Supercritical water gasification is a promising waste-to-energy technology with the ability to convert aqueous and/or heterogeneous organic feedstocks to high-value gaseous products. Reaction behavior of complex molecules in supercritical water can be inferred through knowledge of the reaction pathways of model compounds in supercritical water. In this study methanol, ethanol, and isopropyl alcohol are gasified in a continuous supercritical water reactor at temperatures between 500 and 560 °C, and for residence times between 3 and 8 s. <i>In situ</i> Raman spectroscopy is used to rapidly identify and quantify reaction products. The results suggest the dominance of chain-branching, free radical reaction mechanisms that are responsible for decomposing primary alcohols in the supercritical water environment. The presence of a catalytic surface is proposed to be highly significant for initiating radical reactions. Global reaction pathways are proposed, and mechanisms for free radical reaction initiation, propagation, and termination are discussed in light of these and previously published experimental results.</p><br><p></p></div>

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