Kinetics and mechanism of oxidation of lactic acid by KMnO4 in H2SO4 medium

1985 ◽  
Vol 63 (12) ◽  
pp. 3317-3321 ◽  
Author(s):  
M. M. Girgis ◽  
S. A. El-Shatoury ◽  
Z. H. Khalil

The initial oxidation stages of lactic acid by acid permanganate were investigated. The rate of the induction period was slow and then gradually increased. The kinetics of oxidation were second order, first order with respect to both lactic acid and Mn(VII). The reaction was acid catalyzed. Addition of Mn(II) ions largely increased the rate of the initial stages and decreased the rate of the following stages. The oxidation rate was decreased by the addition of F− or [Formula: see text] ions. The Arrhenius equation was valid for the reaction between 16.5 and 34 °C. Activation parameters were evaluated and a mechanism consistent with the results obtained was proposed.

2011 ◽  
Vol 8 (3) ◽  
pp. 1371-1377
Author(s):  
Shan Jinhuan ◽  
Yang Yafeng

The kinetics of oxidation of isobutylamine and 1,4-butanediamine by home-made potassium ferrate(VI) at different conditions has been studied spectrophotometrically in the temperature range of 288.2 -303.2 K. The results show first order dependence on potassium ferrate(VI) and on each reductant. The observed rate constant (kobs) decreases with the increase of [OH-], the reaction was negative fraction order with respect to [OH-]. A plausible mechanism was proposed and the rate equations derived from the mechanism can explain all the experimental results. The rate constants of the rate-determining step and the thermodynamic activation parameters were calculated.


1992 ◽  
Vol 57 (7) ◽  
pp. 1451-1458 ◽  
Author(s):  
Refat M. Hassan

The kinetics of oxidation of arsenic(III) by hexachloroiridate(IV) at lower acid concentrations and at constant ionic strength of 1.0 mol dm-3 have been investigated spectrophotometrically. A first-order reaction in [IrCl62-] and fractional order with respect to arsenic(III) have been observed. A kinetic evidence for the formation of an intermediate complex between the hydrolyzed arsenic(III) species and the oxidant was presented. The results showed that decreasing the [H+] is accompanied by an appreciable acceleration of the rate of oxidation. The activation parameters have been evaluated and a mechanism consistent with the kinetic results was suggested.


1993 ◽  
Vol 58 (3) ◽  
pp. 538-546 ◽  
Author(s):  
Refat M. Hassan ◽  
Sahr A. El-Gaiar ◽  
Abd El-Hady M. El-Summan

The kinetics of permanganate oxidation of selenium dioxide in perchloric acid solutions at a constant ionic strength of 2.0 mol dm-3 has been investigated spectrophotometrically. A first-order reaction in [MnO4-] and fractional order with respect to selenium(IV) were observed. The reaction rate was found to be pH-independent at lower acid concentrations ([H+] < 0.5 mol dm-3) and was acid-catalyzed beyond this range. Addition of Mn2+ and F- ions leads to the prediction that MnO4- is the sole reactive species in the oxidation process. A tentative reaction mechanism consistent with the reaction kinetics has been proposed.


2011 ◽  
Vol 8 (2) ◽  
pp. 903-909 ◽  
Author(s):  
Shan Jinhuan ◽  
Zhang Jiying

The kinetics of oxidation of diethanolamine and triethanolamine by potassium ferrate(VI)in alkaline liquids at a constant ionic strength has been studied spectrophotometrically in the temperature range of 278.2K-293.2K. The reaction shows first order dependence on potassium ferrate(VI), first order dependence on each reductant, The observed rate constant (kobs) decreases with the increase in [OH-], the reaction is negative fraction order with respect to [OH-]. A plausible mechanism is proposed and the rate equations derived from the mechanism can explain all the experimental results. The rate constants of the rate-determining step and the thermodynamic activation parameters are calculated.


1982 ◽  
Vol 47 (11) ◽  
pp. 2831-2837 ◽  
Author(s):  
Ľudovít Treindl ◽  
Vasil Dorovský

Oxidation of α-ketoglutaric acid with Ce(IV) ions in a solution of sulphuric acid is a reaction of the first order with respect to both Ce(IV) ions and substrate, is acid catalysed, and its rate is proportional to the reciprocal square of the equilibrium HSO4- concentration. From the temperature dependence of the rate constant in 1.5M-H2SO4, the activation parameters were determined as ΔH##f = 57 kJ/mol and ΔS##f = -45 J mol-1 K-1. The redox reaction proper consists apparently of two steps: in the first one, the enol form of α-ketoglutaric acid reacts with Ce(IV) ions with the formation of the corresponding radical; in the second one, the latter is oxidized further with Ce(IV) to give malonic and succinic acids. Conditions are indicated under which α-ketoglutaric acid serves as substrate for the Belousov-Zhabotinskii oscillation reaction in the presence of Ce(IV)-Ce(III) redox catalyst. Oscillations of Ce(IV) and Br2 concentrations, shifted in phase, can be recorded polarographically with a rotating platinum electrode.


2012 ◽  
Vol 9 (1) ◽  
pp. 203-210 ◽  
Author(s):  
Mahantesh A. Angadi ◽  
Suresh M. Tuwar

t-Butylbenzylamine (t-BA) is used as a free base in the synthesis of salbutamol drug. Its mechanism of oxidation was proposed from kinetic studies. The kinetics of oxidation oft-butylbenzylamine by diperiodatoargentate(III) (DPA) was studied spectrophotometrically by monitoring decrease in absorbance of DPA. The reaction was found to be first order each in [DPA] and [t-BA]. The effect of alkali concentration in a wide range on rate of reaction was studied. The rate of reaction was found to be increased with increase in [OH–] in the lower range of [OH–], decreasing effect in the middle range and at higher range again increasing effect on rate of reaction was observed. The added periodate retarded the rate of reaction. The polymerization test revealed that oxidation was occurred with the intervention free radical. A suitable mechanism was proposed for a middle range of [OH–]. The active species of silver(III) periodate for all the three different stages of [OH–] are assayed. Rate law was derived and verified. The oxidative product oft-BA was characterized by LC-ESI-MS spectra.


2011 ◽  
Vol 8 (4) ◽  
pp. 1472-1477
Author(s):  
N. M. I. Alhaji ◽  
S. Sofiya Lawrence Mary

The kinetics of oxidation of glutamic acid (Glu) withN-bromophthalimide (NBP) was studied in perchloric acid medium at 30°C by potentiometric method. The reaction is first order each in NBP and glutamic acid and is negative fractional order in [H+]. Addition of KBr or the reaction product, phthalimide had no effect on the rate. Similarly variation of ionic strength of the medium did not affect the rate of the reaction. Also the rate increased with decrease in dielectric constant of the reaction medium. The thermodynamic parameters were computed from Arrhenius and Eyring plots. A suitable mechanism consistent with the kinetic results has been proposed.


2009 ◽  
Vol 6 (1) ◽  
pp. 237-246 ◽  
Author(s):  
Sapana Jain ◽  
B. L. Hiran ◽  
C. V. Bhatt

Kinetics of oxidation of some aliphatic primary and secondary alcoholsviz.,ethanol, propan-1-ol, propan-2-ol, butan-1-ol, butan-2-ol and 2-methyl butanol by pyridinium chlorochromate (PCC) have been studied in water- perchloric acid medium. The reaction shows first order dependence with respect to pyridinium chlorochromate [PCC] and hydrogen ion [H+]. The rate of oxidation decreases with increase in dielectric constant of solvent suggests ion-dipole interaction. Activation parameters have been evaluated. Products are carbonyl compounds and free radical absence was proved. A tentative mechanism has been proposed.


2009 ◽  
Vol 6 (1) ◽  
pp. 93-98 ◽  
Author(s):  
Annapurna Nowduri ◽  
Kalyan Kumar Adari ◽  
Nageswara Rao Gollapalli ◽  
Vani Parvataneni

Kinetics of oxidation ofL-cystine by hexacyanoferrate(III) was studied in alkaline medium at 30 °C. The reaction was followed spectrophotometrically at λmax = 420 nm. The reaction was found to be first order dependence each on [HCF(III)] and [cystine]. It was found that the rate of the reaction increases with increase in [OH-]. The oxidation product of the reaction was found to be cysteic acid. A plausible mechanism has been proposed to account for the experimental results.


2004 ◽  
Vol 3 (1) ◽  
pp. 1-6
Author(s):  
R. Sridharan ◽  
N. Mathiyalagan

Kinetics of oxidation o Cyclohexanol by N-Chloronicotinamide(NCN) in 50% V/V aqueous acetic acid mixture has been investigated in the presence of HCIO4 and NaCl. The observed rate of oxidation is first-order with respect to oxidation (NCN) and fractional-order with respect to cyclohexanol. A decrease in dielectric constant of the medium increases the rate. Addition of nicotinamide (NA), the reduction product of NCN, has a retarding effect an the rate of oxidation. Arrhenius and activation parameters are calculated. Kinetics of bromination1 and oxidation2,3 of saturated organic compounds by N-bromosuccinimide(NBS) have been received considerable attention. Kinetics and mechanism of oxidation of amino acids by NCN has been reported in aqueous acetic acid medium, we report herein the result of similar studies on the oxidation of cyclohexanol with NCN in aqueous acetic acid medium.


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