Preliminary Study on the Kinetics and Mechanism of the Oxidation of Naphthol Green B by Dichromate Ion in Aqueous Hydrochloric Acid Medium

- The kinetics of the oxidation of naphthol green B (NGB3-) by Cr2O7 2- has been studied in aqueous hydrochloric acid medium at an ionic strength, I = 0.50 mol dm-3 (NaCl), H+ =1.0 10-4 mol dm-3 (HCl) and T = 25 1C. The redox reaction displayed a stoichiometry of 1:1 and obeys the rate law: -dNGB3-/dt = k2NGB3-]Cr2O7 2- . The second order rate constant increases with increase in acid concentration and in the ionic strength of reaction medium. The rates of reaction displayed a positive salt effect. Addition of acrylonitrile to a partially reacted mixture in the presence of excess methanol did not lead to gel formation. Added cations and anions inhibited the naphthol green B - Cr2O7 2- reaction. Results of the Michaelis – Menten plot gave no evidence of intermediate complex formation during the course of the reaction. Based on the results obtained, the reaction is believed to proceed through the outersphere mechanistic pathway

Kinetics and mechanism of oxidation of 1,3- dihydroxybenzene by trioxoiodate(V) ion in aqueous perchloric acid medium

180-182<span style="font-size:15.0pt;mso-bidi-font-size:10.0pt; line-height:115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">The kinetics of oxidation of 1,3-dihydroxybenzene by trioxoiodate(V) ion in aqueous perchloric acid medium has been studied at <span style="font-size:14.0pt; mso-bidi-font-size:9.0pt;line-height:115%;font-family:HiddenHorzOCR;mso-hansi-font-family: " times="" new="" roman";mso-bidi-font-family:hiddenhorzocr;mso-ansi-language:en-us;="" mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">0.20 <span style="font-size:14.0pt; mso-bidi-font-size:9.0pt;line-height:115%;font-family:" times="" new="" roman";="" mso-fareast-font-family:hiddenhorzocr;mso-ansi-language:en-us;mso-fareast-language:="" en-us;mso-bidi-language:ar-sa"="">≤<span style="font-size:14.0pt;mso-bidi-font-size: 9.0pt;line-height:115%;font-family:HiddenHorzOCR;mso-hansi-font-family:" times="" new="" roman";="" mso-bidi-font-family:hiddenhorzocr;mso-ansi-language:en-us;mso-fareast-language:="" en-us;mso-bidi-language:ar-sa"=""> <span style="font-size:14.0pt; mso-bidi-font-size:9.0pt;line-height:115%;font-family:HiddenHorzOCR;mso-hansi-font-family: " times="" new="" roman";mso-bidi-font-family:hiddenhorzocr;mso-ansi-language:en-us;="" mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">[H+]<span style="font-size:14.0pt;mso-bidi-font-size:9.0pt;line-height:115%;font-family: " times="" new="" roman";mso-fareast-font-family:hiddenhorzocr;mso-ansi-language:en-us;="" mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">≤<span style="font-size:14.0pt;mso-bidi-font-size:9.0pt;line-height:115%;font-family: HiddenHorzOCR;mso-hansi-font-family:" times="" new="" roman";mso-bidi-font-family:="" hiddenhorzocr;mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:="" ar-sa"=""> 2.0 <span style="font-size:15.0pt;mso-bidi-font-size:10.0pt; line-height:115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">mol dm-<span style="font-size:11.0pt;mso-bidi-font-size: 6.0pt;line-height:115%;font-family:" times="" new="" roman";mso-fareast-font-family:="" "times="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;="" mso-bidi-language:ar-sa"="">3<span style="font-size:11.0pt; mso-bidi-font-size:6.0pt;line-height:115%;font-family:" times="" new="" roman";="" mso-fareast-font-family:"times="" roman";mso-ansi-language:en-us;mso-fareast-language:="" en-us;mso-bidi-language:ar-sa"=""> <span style="font-size:15.0pt; mso-bidi-font-size:10.0pt;line-height:115%;font-family:" times="" new="" roman";="" mso-fareast-font-family:"times="" roman";mso-ansi-language:en-us;mso-fareast-language:="" en-us;mso-bidi-language:ar-sa"="">under pseudo-first order conditions of an excess [benzenediol] at I<span style="font-size:14.0pt;mso-bidi-font-size:9.0pt;line-height:115%;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-ansi-language:="" en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">= <span style="font-size:15.5pt;mso-bidi-font-size:10.5pt;line-height:115%;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-ansi-language:="" en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">1.10 <span style="font-size:15.0pt;mso-bidi-font-size:10.0pt;line-height:115%;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-ansi-language:="" en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">mol dm-<span style="font-size:11.5pt;mso-bidi-font-size:6.5pt;line-height:115%;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-ansi-language:="" en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">3<span style="font-size:11.5pt;mso-bidi-font-size:6.5pt;line-height:115%;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-ansi-language:="" en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"=""> <span style="font-size:15.0pt;mso-bidi-font-size:10.0pt;line-height:115%;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-ansi-language:="" en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">(NaCIO<span style="font-size:11.5pt;mso-bidi-font-size:6.5pt;line-height:115%;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-ansi-language:="" en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">4<span style="font-size:11.5pt;mso-bidi-font-size:6.5pt;line-height:115%;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-ansi-language:="" en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">). <span style="font-size:15.0pt;mso-bidi-font-size:10.0pt;line-height:115%;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-ansi-language:="" en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">The reaction obeys the rate expression…</span

Kinetics and mechanism of the oxidation of thiocyanate ion by di-m-oxo-tetrakis(1,10-phenanthroline)-dimanganese (III,IV) ion in acid medium

The kinetics of oxidation of thiocyanate ion by di-m-oxo-tetrakis(1,10-phenanthroline)dimanganese(III,IV) perchlorate in acid medium has been investigated. The reaction follows first order in both the oxidant and the reductant. The reaction is catalysed by hydrogen ion and the rate dependence given as k2 = a + b[H+]. The reaction rate is not affected by changes in the ionic strength and dielectric constant of the reaction medium. The reaction did not induce polymerization of acrylamide and the presence of NO3- or HCOO- had no effect on the rate. A plausible mechanism involving proton coupled electron transfer (PCET) is proposed. Key words: Kinetics, mechanism, oxidation, thiocyanate, di-m-oxo-tetrakis(1,10-phenanthroline)-dimanganese (III,IV) (Global Journal of Pure and Applied Sciences: 2002 9(1): 105-112

Oxidation of ethylenediaminetetraacetate by tris(diimine) iron(III) complexes and the dodecatungstocobaltate(III) ion: a comparative kinetic and mechanistic study

The stoichiometry and kinetics of the oxidation of ethyl-enediaminetetraacetate by [Fe(phen)3]3+, [Fe(bipy)3]3+ and [CoIIIW12O40]5- were studied in aqueous HClO4. Reaction rates were first order with respect to the oxidants and the reductant, and the dependence of the second order rate constant k2 on [H+] is given by k2 = a + b[H+ -. The primary products were CO2, CH2O and (CH2NH2)2. Schuster treatment is employed to show that the reactions occur by the outersphere mechanism

Electron transfer at tetrahedral cobalt(II). Part II. Kinetics of silver(I) ion catalysed reduction of peroxodisulphate

The kinetics of the silver(I) ion catalysed reduction of peroxodisulphate by 12-tungstocobaltate(II) anion in aqueous HC1O4 has been studied. Although the reaction in the range [H+ ] = 0.1−1.0 M was acid-independent, it was first-order each in AgI, the oxidant and the reductant. We propose that reaction proceeds by univalent changes with the production of free radical intermediates. The reduction is rationalised in terms of the outer-sphere mechanism

Kinetics of the oxidation of oxalic acid by di-μ-tetrakis(1,10-phenanthroline)-dimanganese (III,IV) perchlorate in aqueous acid medium

The kinetics and stoichiometry of the oxidation of oxalic acid with [(phen)2MnIIIO2MnIV(phen) 2](ClO4)3 have been studied in aqueous acid medium. The reaction follows the general rate law: -3/2d[MnIIIO2MnIV]/dt -{a+b[H+]}[MnIIIO2MnIV][H 2C2O4] with a=0.36 s-1 and b=52.80 M-1 s-1 at 27.0±0.1°C, [H+]=0.05 M and I=0.50 M (NaCl) and λ=555 nm. The kinetic and spectroscopic findings support the proton coupled electron transfer pathway and is hereby proposed for the title reaction

Kinetics of reduction of triaminotolyldiphenylmethane chloride (rosaniline hydrochloride) by hydroxide ions in aqueous medium

967-969<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Kinetics and mechanism of reduction of rosaniline hydrochloride (RH) by hydroxide ions have been studied in aqueous medium at 30°C at ionic strength of 1.0 mol dm-3 (NaCl)...</span

Oxidation of glutathione by diaquatetrakis(2,2′-bipyridine)-μ-oxo diruthenium(III) ion in aqueous acidic solutions

The kinetics of the oxidation of glutathione by diaquatetrakis(2,2′-bipyridine)-μ-oxo diruthenium(III) ion in aqueous HClO4 have been investigated. The reaction obeys the empirical rate law:-2d[oxidant]/d t = k[oxidant][reductant]/[H+] where k = 7.42 ± 0.40 × 10-3 s-1 at 25.5 °C, [H+] = 0.005-0.05 M and I = 1.0 M (LiClO4). Free radicals are important in the reaction and a mechanism consistent with the experimental results has been postulated