Mécanisme des réactions du chlorite et du dioxyde de chlore. 1. Stoechiométrie des réactions du chlorite et cinétique en présence d'ortho-tolidine

1981 ◽  
Vol 59 (8) ◽  
pp. 1177-1187 ◽  
Author(s):  
Guy Schmitz ◽  
Henri Rooze
Keyword(s):  
Chlorine Dioxide ◽  
Perchloric Acid ◽  
Hypochlorous Acid ◽  
Chloride Ions ◽  
Sodium Chlorite ◽  
Kinetic Investigation ◽  
Acid Solutions ◽  
Fast Reaction ◽  
Rate Determining Step ◽  
Chlorous Acid

The relative amount of chlorine dioxide produced by the disproportionation of sodium chlorite increases as the concentrations of chlorite and chloride ions increase. It passes through a minimum when the concentration of perchloric acid varies from 2 M to 0.01 M. The fast reaction between chlorite and hypochlorous acid is a part of the mechanism of this disproportionation and its stoichiometry was also investigated. The relative amount of chlorine dioxide produced depends on the method of mixing the reactants and on the acidity. It increases if the concentration of chlorite increases and can exceed the amount predicted by:[Formula: see text]Ortho-tolidine reacts very rapidly with chlorine and with chlorine dioxide but not with chlorous acid. In perchloric acid solutions (pH < 2.5) the product of its oxidation has a considerable absorption with a maximum at 440 nm (ε = 59700 M−1 cm−1). Chlorine reacts more rapidly with ortho-tolidine than with chlorous acid. The kinetic investigation of the disproportionation of chlorous acid is thus simplified by the use of ortho-tolidine. With added chloride ions the rate determining step is HClO2 + Cl− + H+ → 2HClO with a rate constant[Formula: see text]The most reliable values for the free enthalpy of formation of oxychlorine compounds are selected from the literature.

Electrochemical oxidation of squaric and croconic acids on Pt and Pt surfaces modified by underpotential heavy metal monolayers in acid solutions

1987 ◽  
Vol 65 (2) ◽  
pp. 397-403 ◽  
Author(s):  
D. Sazou ◽  
G. Kokkinidis
Keyword(s):  
Electrochemical Oxidation ◽  
Perchloric Acid ◽  
Electrochemical Behaviour ◽  
Sweep Rate ◽  
Hydration Reaction ◽  
Acid Solutions ◽  
Rotating Disc ◽  
Rate Determining Step ◽  
Controlled Potential ◽  
Reaction Orders

The electrochemical oxidation of squaric and croconic acids on platinum in aqueous perchloric acid solutions has been investigated by means of cyclic voltammetry, rotating disc electrode, potentiostatic transients and controlled-potential electrolysis. The kinetic parameters (Tafel slopes, reaction orders) have been determined on the foot of the wave by varying the sweep rate, the angular velocity, depolarizer concentration, and perchloric acid concentration. A probable mechanism has been proposed for the overall oxidation processes. It involves two charge-transfer steps followed by the desorption of product, which is the rate-determining step. The oxidation product is immediately deactivated by a rapid hydration reaction. Also, the effect of underpotential Tl, Pb, and Bi monolayers on the electrochemical behaviour of squaric and croconic acids has been examined.

STUDIES IN THE POLYOXYPHENOL SERIES: VIII. THE OXIDATION OF SUBSTANCES RELATED TO VANILLIN WITH SODIUM CHLORITE AND CHLORINE DIOXIDE

1955 ◽  
Vol 33 (1) ◽  
pp. 82-96 ◽  
Author(s):  
C. D. Logan ◽  
R. M. Husband ◽  
C. B. Purves
Keyword(s):  
Hydrogen Peroxide ◽  
Chlorine Dioxide ◽  
Sodium Chlorite ◽  
Veratric Acid ◽  
Simultaneous Formation ◽  
Aqueous Sodium ◽  
Sharp Distinction ◽  
Slow Reaction ◽  
Ph Values ◽  
Chlorous Acid

The research confirmed the fact that chlorine dioxide and sodium chlorite were not equivalent in their oxidizing properties. At 22 °C. or less, the oxidation of pyrogallol by aqueous sodium chlorite at pH 6 was very slow, but became very rapid on the acid side of pH 3.5. The amorphous, colored products probably did not include purpurogallin. Under similar circumstances p-hydroxybenzaldehyde was unaffected at pH 6; 22% was oxidized to p-benzoquinone (Dakin's reaction) at pH 5, and this amount increased to 39% at pH 1. The yield of benzoquinone was about 24% regardless of pH within the above range when aqueous chlorine dioxide was the oxidant. Sodium chlorite at pH 0.9 produced a 91% yield of methoxy-p-quinone from methoxy-p-hydroquinone; at pH 4 this product was mixed with 56% of 4,4′-dimethoxydiquinone, but near pH 6 a slower oxidation did not proceed beyond 4,4′-dimethoxyquinhydrone. Aqueous chlorine dioxide yielded at least 92% of monomeric methoxyquinone at all pH values between 1 and 6, probably in accord with the equation,[Formula: see text] The simultaneous formation of hydrogen peroxide was suspected, but not proved. In sharp distinction to the behavior of free phenols, veratraldehyde was not oxidized by aqueous chlorine dioxide between pH 6 and pH 3, but at pH 1 a slow reaction yielded up to 15% of veratric acid. Sodium chlorite produced about 92% of the same acid at pH 1 and pH 4, but its action was negligible at pH 5. Since by-product chlorine dioxide was ineffective at pH 4, it was possible to confirm the validity of the Jeanes–Isbell equation for the reduction of chlorous acid:[Formula: see text]The oxidation of acetylated vanillin was complicated by the occurrence of deacetylation. Red, chlorinated oils with quinoidal properties were also formed in most of the above oxidations.

The Oxidation of Tetrahydrofuran by Ruthenium Tetroxide

1972 ◽  
Vol 50 (19) ◽  
pp. 3129-3134 ◽  
Author(s):  
Donald G. Lee ◽  
Matthijs Van Den Engh
Keyword(s):  
Perchloric Acid ◽  
Activation Parameters ◽  
Isotopic Labeling ◽  
Acid Solutions ◽  
Ruthenium Tetroxide ◽  
Rate Determining Step ◽  
Rate Of Reaction ◽  
Hydride Abstraction ◽  
Aqueous Perchloric Acid ◽  
Kinetics Of

The kinetics of the oxidation of tetrahydrofuran by ruthenium tetroxide in aqueous perchloric acid solutions have been investigated. The rate of reaction is found to be directly dependent on the concentrations of oxidant and reductant, but inversely dependent on the acidity of the medium. A mechanism involving hydride abstraction in the rate determining step was found to be consistent with the evidence obtained from isotopic labeling and an analysis of the activation parameters (ΔH≠ = 14.0 kcal/mol, ΔS≠ = −18.4 e.u.) of the reaction. This conclusion is further substantiated by noting the similarity between the reactions of ruthenium tetroxide with alcohols and ethers.

Analyses of chlorine dioxide, chlorous acid, chlorite, chlorate, and chloride in composite mixtures

1968 ◽  
Vol 46 (12) ◽  
pp. 2061-2064 ◽  
Author(s):  
C. C. Hong ◽  
W. H. Rapson
Keyword(s):  
Chlorine Dioxide ◽  
Analytical Procedure ◽  
Total Concentration ◽  
Chloride Ion ◽  
Molar Absorptivity ◽  
Chloride Ions ◽  
Neutral Solution ◽  
Chlorous Acid

An analytical procedure was devised to determine chlorine dioxide, chlorous acid, and chlorite, chlorate, and chloride ions in composite mixtures. Chlorine dioxide was determined spectrophotometrically at 360 mµ. After the removal of chlorine dioxide by passing air through the solution, the total concentration of chlorous acid and chlorite ion in the solution was determined spectrophotometrically at 250 mµ where the two species have the same molar absorptivity. The total concentration of chlorous acid, chlorite ion, and chlorate ion was determined by iodimetric titration. Chloride ion was determined by the Mohr titration in neutral solution.

The Oxidation of 2-Propanol by Ruthenium Tetroxide

1972 ◽  
Vol 50 (13) ◽  
pp. 2000-2009 ◽  
Author(s):  
Donald G. Lee ◽  
Matthijs van den Engh
Keyword(s):  
Perchloric Acid ◽  
Acid Solutions ◽  
Ruthenium Tetroxide ◽  
High Acid ◽  
Rate Determining Step ◽  
Carbonium Ion ◽  
Hydride Abstraction ◽  
Aqueous Perchloric Acid ◽  
Kinetics Of ◽  
Very High

The kinetics of the oxidation of 2-propanol by ruthenium tetroxide in aqueous perchloric acid solutions have been investigated. The results indicate that the two mechanisms pertain; at moderate acidities (1–6.5 M HClO4) the rate determining step involves hydride abstraction while at very high acid concentrations the rate determining step becomes carbonium ion formation.

scholarly journals An efficiency analysis for the production of chlorine dioxide by the electrolysis of brine in seawater desalination plants

2018 ◽  
Vol 54 (2) ◽  
pp. 127-133 ◽  
Author(s):  
Chiung-Ta Wu ◽  
Chen-Yu Chang ◽  
Yi-Ying Li ◽  
Yu-Lun Kuan ◽  
Po-Hsiung Lin
Keyword(s):  
Chlorine Dioxide ◽  
Precious Metal ◽  
Hypochlorous Acid ◽  
Economic Value ◽  
Efficiency Analysis ◽  
Disinfection Byproducts ◽  
Sodium Chlorite ◽  
Efficiency Evaluation ◽  
Constant Concentration ◽  
Desalination Plants

Abstract A previous study by the authors evaluated the efficiency of producing multi-oxidants using anodes coated in precious metal. This study showed that a titanium anode coated in ruthenium generates the largest amount of active chlorine (chlorine dioxide). The results from the efficiency evaluation also show that DuPont Nafion N-2030 ion film is the most efficient of the diaphragms that were tested. To increase the recovery rate for ClO2, this study optimizes the composition of the anode electrolyte. Sodium chlorite is added into the brine and an electrolysis reaction is performed at 40 °C and 12 V for batch operation. The principal product is ClO2 with a maximum concentration of 1,074 mg L−1. During continuous electrolysis, when the inflow rate for the anode electrolyte is increased to 120 mL min−1, ClO2 is produced at a constant concentration of 60 mg L−1 after 30 minutes. An analysis of the multi-oxidants generated from brine to detect disinfection byproducts shows very little trichloromethane is formed, much less than the standard for total trihalomethanes in drinking water in Taiwan (0.1 mg L−1). The disinfection efficiency of the multi-oxidant produced in this study is about three times greater than that of commercial hypochlorous acid. These results show that multi-oxidant products retrieved by recycling brine from desalination plants are commercially applicable and have economic value.

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