Substituent effects in cooxidation: Cr(VI) – oxalic acid – sulfoxides systems

1987 ◽  
Vol 65 (10) ◽  
pp. 2421-2424 ◽  
Author(s):  
C. Srinivasan ◽  
P. Pandarakutty Jegatheesan ◽  
S. Rajagopal ◽  
N. Arumugam
Keyword(s):  
Oxalic Acid ◽  
Phenyl Ring ◽  
Substituent Effects ◽  
Aluminium Nitrate ◽  
First Order ◽  
Kinetic Information ◽  
Hammett Correlation ◽  
Analogous Manner ◽  
Reaction Constant ◽  
Kinetics Of

The kinetics of cooxidation of several substituted phenyl methyl sulfoxides and oxalic acid with Cr(VI) have been carried out in the presence of perchloric acid. The reaction is first order each in sulfoxide, oxalic acid, Cr(VI), and H+. The products of oxidation are sulfones and carbon dioxide. Electron-releasing groups in the phenyl ring accelerate the rate while electron-withdrawing groups retard it. The Hammett correlation yields a reaction constant of −0.927 ± 0.08 (r = 0.994) at 313 K. Addition of aluminium nitrate prevents the occurrence of cooxidation. Based on the kinetic information a suitable mechanism has been proposed. Diaryl sulfoxides behave in an analogous manner in the cooxidation.

scholarly journals Phenylcarbamic acid derivatives with integrated n-phenylpiperazine moiety in the structure – kinetics of alkaline hydrolysis study / Deriváty kyseliny fenylkarbámovej s integrovanou n-fenylpiperazínovou zložkou v štruktúre – štúdium kinetiky alkalickej hydrolýzy

2015 ◽  
Vol 62 (2) ◽  
pp. 38-42
Author(s):  
Stankovičová M. ◽  
Miháliková V. ◽  
Mezovský Ľ. ◽  
Lašáková A. ◽  
Medlenová V. ◽  
...  
Keyword(s):  
Alkaline Hydrolysis ◽  
Phenyl Ring ◽  
Arrhenius Equation ◽  
Sodium Hydroxide Solution ◽  
Antimycobacterial Activity ◽  
First Order ◽  
Rate Of Hydrolysis ◽  
Pseudo First Order ◽  
Kinetics Of ◽  
Hydrolysis Of

AbstractIn present work, we have studied kinetics of alkaline hydrolysis of 14 compounds, which are phenylcarbamic acid derivatives with integrated N-phenylpiperazine moiety in the structure. The compounds possessed moderate antiarrhythmic and antimycobacterial activity. Their hydrolysis was carried out in an aqueous medium ethanol sodium hydroxide solution. The course of the hydrolysis was observed spectrophotometrically in visible as well as in ultraviolet regions. The pseudo-first order rate constants were calculated at several temperatures. The values of the activation energy EAwere determined by the Arrhenius equation. The rate of hydrolysis of the compounds under the study increase with the increase in temperature and it has been differentiated according to the substitution of N-phenylpiperazine as well as to the alkoxy substitution on phenyl ring.

Kinetics of reactions of para-substituted phenyl isocyanates with amines and alcohols

1991 ◽  
Vol 56 (8) ◽  
pp. 1662-1670 ◽  
Author(s):  
Ivan Danihel ◽  
Falk Barnikol ◽  
Pavol Kristian
Keyword(s):  
Transition State ◽  
Solvent Effects ◽  
Rate Constants ◽  
Substituent Effects ◽  
Steric Effects ◽  
Stopped Flow ◽  
Partial Charges ◽  
Hammett Correlation ◽  
One Step ◽  
Kinetics Of

The reaction of para-substituted phenyl isocyanates with amines and alcohols was studied by stopped-flow method. The Hammett correlation obtained showed that the sensitivity of the above mentioned reactions toward substituent effects is the same as that of analogous reactions of phenyl isothiocyanates (ρ ~ 2). The rate constants of these reactions were found to be affected more by steric effects than by solvent effects. An one step multicentre mechanism with partial charges in transition state has been proposed for the title reactions.

Substituent effects on azo coupling of indoles

1993 ◽  
Vol 71 (12) ◽  
pp. 2144-2149 ◽  
Author(s):  
Hassan A. Albar ◽  
Ahmad S. Shawali ◽  
Magda A. Abdaliah
Keyword(s):  
Diazonium Salt ◽  
Substituent Effects ◽  
General Mechanism ◽  
Coupling Reactions ◽  
Azo Coupling ◽  
Straight Line ◽  
Reaction Constant ◽  
Methyl Derivatives ◽  
Rate Limiting ◽  
Kinetics Of

The kinetics of the azo coupling of eight para-substituted benzenediazonium tetrafluoroborates 2a–h with indole and its 1-, 2-,and 3-methyl derivatives 1a–d, respectively, were studied in acetonitrile at 25 °C under pseudo-first-order conditions. The relation k1(obs) = k2[diazonium salt] was found applicable in all cases. The logarithms of the rate constants k2 for each reaction series were correlated by the Hammett equation. A plot of the values of the reaction constant, ρ, obtained against the acidity constants pKa of 1a–d gave a straight line: ρ = 2.97 – 0.15 pKa. These results indicate that the azo-coupling reactions of indoles 1a–d follow one general mechanism involving rate-limiting initial electrophilic attack at the 3-position for all four compounds, contrary to the previous conclusion of Jackson and Lynch that the final deprotonation step is rate limiting.

scholarly journals Mechanism of Oxidation of (p-Substituted Phenylthio)acetic Acids withN-Chlorosaccharin

2011 ◽  
Vol 8 (1) ◽  
pp. 159-166 ◽  
Author(s):  
N. M. I. Alhaj ◽  
A. M. Uduman Mohideen ◽  
S. Sofia Lawrence Mary
Keyword(s):  
Phenyl Ring ◽  
Reaction Rate ◽  
Water Medium ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Rate Determining Step ◽  
Composition Variation ◽  
Mechanism Of Oxidation ◽  
Kinetics Of ◽  
Acetic Acids

The kinetics of oxidation of (phenylthio)acetic acid (PTAA) withN-chlorosaccharin (NCSA) have been studied potentiometrically in 80:20 (v/v) acetonitrile-water medium at 298 K. The reaction is first-order each with respect to PTAA and NCSA and shows a negative dependence on [H+]. NCSA itself is shown to be the active oxidizing species. Effects of ionic strength variation, added saccharin, added acrylonitrile, added NaCl and solvent composition variation have been studied. Effect of substituents on the reaction rate has been analysed by employing various (p-sustituted phenylthio)acetic acids. The electron-releasing substituent in the phenyl ring of PTAA accelerates the reaction rate while the electron-withdrawing substituent retards the rate. The excellently linear Hammett plot yields a large negative ρ value, supporting the involvement a chlorosulphonium ion intermediate in the rate-determining step.

scholarly journals COMPARATIVE STUDY OF OXIDATIVE TRANSFORMATION OF ALIPHATIC ALCOHOLS BY CE(IV) -ONE ELECTRON KINETICS

2020 ◽  
pp. 1-2
Author(s):  
Mamta Baser ◽  
B. K. Dangarh ◽  
Y.K. Mishra
Keyword(s):  
Comparative Study ◽  
Activation Parameters ◽  
Aliphatic Alcohols ◽  
Experimental Conditions ◽  
First Order ◽  
Reaction Constant ◽  
The Comparative Study ◽  
Kinetics Of ◽  
Acetonitrile Medium ◽  
Good Agreement

The comparative study of oxidation of aliphatic alcohols likes methanol, ethanol and propanol was carried out by CAN in the presence of perchloric acid in acetonitrile medium. The reaction is first order with respect to [substract], [oxidant] and [H+] concentration. The kinetics of the reaction was followed spectrophotometrically at λmax = 400 nm. The reactions were studied at different temperature [303 to 323 K]. A possible mechanism is proposed here. The reaction constant involved in the mechanism have been computed. There is good agreement between the observed and calculated rate constant under different experimental conditions. The activation parameters have been evaluated.

scholarly journals Pyrolysis Reaction Kinetics of Styrofoam Plastic Waste

2021 ◽  
Vol 9 (1) ◽  
pp. 57-62
Author(s):  
Feybi A. G. Kauwo ◽  
I Dewa K. Anom ◽  
John Z. Lombok
Keyword(s):  
Activation Energy ◽  
Reaction Kinetics ◽  
Arrhenius Equation ◽  
Plastic Waste ◽  
Energy Value ◽  
Pyrolysis Reaction ◽  
First Order ◽  
Liquid Smoke ◽  
Reaction Constant ◽  
Kinetics Of

Pyrolysis at the temperature range of 170 °C-237 °C against polystyrene (Styrofoam) type plastic waste is carried out without a catalyst and added a catalyst. The purpose of this research was to study the reaction kinetics of Styrofoam pyrolysis to liquid smoke products. Pyrolysis using a series of tools made of glass to observe the processes that occur in the reactor. The results showed that Styrofoam pyrolysis for liquid smoke products without catalyst and added catalyst took place in the first-order reaction. The kinetics of the pyrolysis reaction without a catalyst to observe the formation of liquid smoke products obtained by the equation of the reaction constant following the Arrhenius equation k = Ae2111.4 / T, with an activation energy value (Ea) of 17.554 x 103 kJ/mol and pyrolysis using a catalyst obtained k = Ae10330/T, with an activation energy value (Ea) of 85.883x103 kJ/mol. Using catalysts during pyrolysis will reduce the temperature so that the reaction will be slow.

Synthesis and properties of phenyl substituted derivatives of 2-phenyl-1,1,3,3-tetramethylguanidine

1987 ◽  
Vol 65 (3) ◽  
pp. 626-629 ◽  
Author(s):  
Przemyslaw Pruszynski
Keyword(s):  
Mass Spectrometry ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Phenyl Ring ◽  
Substituent Effects ◽  
Ultraviolet Spectrophotometry ◽  
Elemental Analyses ◽  
Reaction Constant ◽  
Substituent Constants ◽  
Derivatives Of

A series of 17 phenyl substituted derivatives of 2-phenyl-1,1,3,3-tetramethylguanidine was synthesized. The structure and purity of these compounds were checked by means of elemental analyses, mass spectrometry, ultraviolet spectrophotometry, and 1H nuclear magnetic resonance. The pKa values were determined and are discussed in terms of substituent effects using Hammett substituent constants. The Hammett reaction constant ρ = 1.84 ± 0.05 was found to be much lower for para and meta substituted compounds than for anilines, even though the phenyl ring is attached directly to the basic centre in both cases.

scholarly journals Kinetics and mechanism of the oxidation of some substituted aldonitrones by quinolinium chlorochromate in aqueous DMF medium in the absence and presence of oxalic acid

2009 ◽  
Vol 74 (2) ◽  
pp. 171-182 ◽  
Author(s):  
Govindasamy Rajarajan ◽  
Natesan Jayachandramani ◽  
Subramanian Manivarman ◽  
Jayaraman Jayabharathi ◽  
Venugopal Thanikachalam
Keyword(s):  
Dielectric Constant ◽  
Ionic Strength ◽  
Oxalic Acid ◽  
Reaction Rate ◽  
Activation Parameters ◽  
Experimental Conditions ◽  
First Order ◽  
Discernible Effect ◽  
Reactive Oxidant ◽  
Kinetics Of

The kinetics of the oxidation of aldonitrones (nitrone) by quinolinium chlorochromate (QCC) was determined in 50 % DMF-water in the absence and presence of oxalic acid in order to study the effect of oxalic acid. It was considered worthwhile to investigate whether it undergoes co-oxidation or just functions as a catalyst in the reaction. The reaction was followed iodometrically. Under the employed experimental conditions, the reaction is first order each with respect to concentration of nitrone, QCC, and oxalic acid and fractional order with respect to H+ concentration. There was no discernible effect with increasing in ionic strength but the rate of oxidation decreased with decreasing dielectric constant of the medium. Addition of MnSO4 had a significant and acrylonitrile no effect on the reaction rate. A mechanism involving protonated nitrone and QCC as the reactive oxidant is proposed. The activation parameters were calculated and are presented.

Kinetic of oxidation of methyl orange by vanadium(V) under conditions VO2+ and decavanadates coexist: Catalysis by Triton X-100 micellar medium

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Methyl Orange ◽  
Solution Ph ◽  
Vanadium Concentration ◽  
Limiting Behavior ◽  
First Order ◽  
First Order Kinetics ◽  
Ph Range ◽  
Kinetic Pattern ◽  
Triton X ◽  
Kinetics Of

The kinetics of oxidation of methyl orange by vanadium(V) {V(V)} has been investigated in the pH range 2.3-3.79. In this pH range V(V) exists both in the form of decavanadates and VO2+. The kinetic results are distinctly different from the results obtained for the same reaction in highly acidic solution (pH < 1) where V(V) exists only in the form of VO2+. The reaction obeys first order kinetics with respect to methyl orange but the rate has very little dependence on total vanadium concentration. The reaction is accelerated by H+ ion but the dependence of rate on [H+] is less than that corresponding to first order dependence. The equilibrium between decavanadates and VO2+ explains the different kinetic pattern observed in this pH range. The reaction is markedly accelerated by Triton X-100 micelles. The rate-[surfactant] profile shows a limiting behavior indicative of a unimolecular pathway in the micellar pseudophase.

The Kinetics of Glucose Decomposition with Sulfate Reduction in the Anaerobic Fluidized Bed Reactor

1993 ◽  
Vol 28 (2) ◽  
pp. 135-144 ◽  
Author(s):  
S. Matsui ◽  
R. Ikemoto Yamamoto ◽  
Y. Tsuchiya ◽  
B. Inanc
Keyword(s):  
Sulfate Reduction ◽  
Fluidized Bed ◽  
Kinetic Equations ◽  
Fluidized Bed Reactor ◽  
Order Reaction ◽  
First Order Reaction ◽  
First Order ◽  
Glucose Decomposition ◽  
Reaction Equations ◽  
Kinetics Of

Using a fluidized bed reactor, experiments on glucose decomposition with and without sulfate reduction were conducted. Glucose in the reactor was mainly decomposed into lactate and ethanol. Lactate was mainly decomposed into propionate and acetate, while ethanol was decomposed into propionate, acetate, and hydrogen. Sulfate reduction was not involved in the decomposition of glucose, lactate, and ethanol, but was related to propionate and acetate decomposition. The stepwise reactions were modeled using either a Monod expression or first order reaction kinetics in respect to the reactions. The coefficients of the kinetic equations were determined experimentally. The modified Monod and first order reaction equations were effective at predicting concentrations of glucose, lactate, ethanol, propionate, acetate, and sulfate along the beight of the reactor. With sulfate reduction, propionate was decomposed into acetate, while without sulfate reduction, accumulation of propionate was observed in the reactor. Sulfate reduction accelerated propionate conversion into acetate by decreasing the hydrogen concentration.

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