Einige Reaktionen des Chlordioxyds und der chlorigen Säure

Bray, William C.

doi:10.1002/zaac.19060480118

Cited by 16 publications

(4 citation statements)

References 9 publications

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“…In the second stage, however, around both 260 and 360 nm, a relatively slow decrease of the absorbance may be realized. Because alkaline decomposition of chlorine dioxide is well-known from the literature, , as a first step, one should check whether the decay of chlorine dioxide really belongs to the second stage of the reaction or it is simply due to the alkaline degradation of chlorine dioxide described by the following reaction: This equation explicitly shows that, during the course of alkaline decomposition, chlorite ion must form, which means that near 260 nm, where chlorite has a significant molar absorbance (ε ClO 2 – = 147 ± 3 M –1 cm –1 , which agrees soundly with the one determined by Furman and Margerum), the absorbance should have increased (chlorate does not have any significant absorption at this wavelength, and chlorine dioxide just slightly absorbs the light, having a molar absorptivity of ε ·ClO 2 = 51.9 ± 0.8 M –1 cm –1 ). Instead of that, we observed a slight decrease in the second slower stage of the reaction (as seen in Figure ), which indirectly rules out the possibility that in this stage the undesired side reaction of • ClO 2 decomposition occurs alone.…”

Section: Results and Discussionsupporting

confidence: 66%

“…From this figure, it is evident that, although alkaline decomposition of chlorine dioxide cannot be avoided, the major process responsible for the decay of chlorine dioxide is the second stage of the title reaction. From the rate equation proposed by Bray (v 1 = k 1 [ • ClO 2 ] 2 [OH – ]), our measurements provided k 1 = 160 ± 20 M –2 s –1 taking into consideration that p K a3 of phosphoric acid is 11.75 . At the same time, it means that the correct quantitative evaluation of the kinetic curves at the second stage of the sulfide–chlorine dioxide reaction requires consideration of this process as well (see later the quantitative description of the second stage of the reaction).…”

Section: Results and Discussionmentioning

confidence: 94%

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Kinetics of the Two-Stage Oxidation of Sulfide by Chlorine Dioxide

et al. 2018

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The sulfide-chlorine dioxide reaction was found to have two distinct kinetic stages at alkaline conditions. The first stage proceeds so rapidly that it can only be measured by a stopped-flow technique at low temperature and leads to the parallel formation of polysulfide and sulfate as sulfur-containing products. At the same time, chlorite, chlorate, and chloride are produced from chlorine dioxide in detectable amounts, suggesting a complex stoichiometry. A nine-step kinetic model including short-lived intermediates like sulfide radical and HSClO is proposed to describe the kinetic data in this rapid stage. In an excess of chlorine dioxide, the first stage is followed by a significantly slower one to be measured by conventional UV-vis spectroscopy at room temperature. Considering that tetrasulfide is formed during the first rapid course of the reaction, the subsequent slow kinetic stage can only be described by the direct oxidation of tetrasulfide by chlorine dioxide and, surprisingly, the tetrasulfide-catalyzed disproportionation of chlorine dioxide.

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Section: Results and Discussionsupporting

confidence: 66%

Section: Results and Discussionmentioning

confidence: 94%

Kinetics of the Two-Stage Oxidation of Sulfide by Chlorine Dioxide

et al. 2018

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“…They are the only reactions in which ClO 2 is consumed. At high pH, most of the ClO 2 disproportionates to ClO 3 - , ClO 2 - , and Cl - (see reaction M12), hence the observed lower ClO 2 absorbances at high pH (see Figure ). − Rapid autocatalytic formation of ClO 2 is halted by reaction M13 . The Cl - obtained from the reduction of HOCl by the substrate species (reactions M4 and M5) halts the uncontrolled buildup of ClO 2 (reaction M13).…”

Section: Mechanismmentioning

confidence: 99%

Oxidation of Formaldehyde by Chlorite in Basic and Slightly Acidic Media

1998

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The reaction of chlorite and formaldehyde was studied in basic and slightly acidic media. Though the expected product was CO 2 , the oxidation of HCHO, however, gave nearly quantitative formation of ClO 2 , the oxidation product of ClO 2 -. In excess HCHO the stoichiometry of the reaction was deduced as 3ClO 2 -+ HCHO + 2H + f HCOOH + 2ClO 2 (aq) + Cl -+ 2H 2 O; but in high excess of ClO 2the stoichiometry was 6ClO 2 -+ HCHO + 4H + f CO 2 (g) + 4ClO 2 (aq) + 3H 2 O + 2Cl -. The reaction is autocatalytic in HOCl. The first step of the reaction produces HOCl, which catalyzes the formation of ClO 2 and further oxidation of HCOOH to CO 2 . ClO 2 was found to be relatively unreactive toward HCHO and HCOOH, and hence it accumulated rapidly.

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“…In general, the reaction is faster in lower pH conditions, although no relationship was evident. At constant [ClO 2 - ] 0 and [HMSA] 0 , the maximum ClO 2 concentrations did not seem to vary with pH, except for the expected decrease at higher pH due to ClO 2 hydrolysis a were obtained by running the reaction in different buffers.…”

Section: Resultsmentioning

confidence: 91%

Oxyhalogen−Sulfur Chemistry: Oxidation of Hydroxymethanesulfinic Acid by Chlorite

1996

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The reaction between chlorite and hydroxymethanesulfinic acid, HOCH2SO2H, (HMSA) has been studied in the pH range 4−8. The reaction is very complex and has a variable stoichiometry that is dependent on ratio of the oxidant to the reductant. In excess HMSA, the stoichiometry is ClO2 - + HOCH2SO2H → SO4 - + HCHO + Cl- + 2H+ while in excess ClO2 - the stoichiometry is 3ClO2 - + 2HOCH2SO2H → 2SO4 2- + 2HCOOH + 4H+ + 3Cl-. The reaction is very fast and is characterized by a short induction period (≈1 s) which is followed by a rapid and autocatalytic ClO2 production. The first stage in the oxidation is the cleavage of C−S bond to form SO4 2- and HCHO. In the presence of excess oxidant the HCHO is oxidized to HCOOH. After prolonged standing (72 h or more), the HCOOH can be oxidized to CO2; giving a third possible stoichiometry. The rate-determining step is a 2-electron oxidation of HMSA by ClO2 - to give the sulfonic acid HOCH2SO3H. A 19-reaction mechanism is used to simulate the reaction. There is reasonable agreement between the experiments and simulations.

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Einige Reaktionen des Chlordioxyds und der chlorigen Säure

Abstract: 1. Die Zersetzung von CLO2 unter verschiendenen Umständen und seine Reaktion mit OH′ wurde untersucht und erörtert.

Cited by 16 publications

References 9 publications

Kinetics of the Two-Stage Oxidation of Sulfide by Chlorine Dioxide

Kinetics of the Two-Stage Oxidation of Sulfide by Chlorine Dioxide

Oxidation of Formaldehyde by Chlorite in Basic and Slightly Acidic Media

Oxyhalogen−Sulfur Chemistry: Oxidation of Hydroxymethanesulfinic Acid by Chlorite

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