Reactions with chlorite

Lindgren, B. O. and T. Nilsson. 1974. Oxidation of lignin model compounds with chlorine dioxide and chlorite. Reactions with stilbenes. Acta Chem. Scand. 28 847-852. 

In more complex reactions, such as the chlorite reaction, with several phases having common elements on each side of the reaction, determining the covariance will be a tedious business but theoretically very straightforward, as long as sufficient data on the individual calorimetric experiments is available in the literature. Whether the covariance will lead to an increase or a decrease in the temperature standard error is hard to say until the calculation is performed. 

Sodium Hypochlorite—Acid—Sodium Chlorite System. In this method, hydrochloric or sulfuric acid is added into a sodium hypochlorite [7681 -52-9] NaOCl, solution before reaction with the sodium chlorite (118). 

The reaction chemistry changes when the initial reactant concentrations are low or there is excess hypochlorous acid present. The [CI2O2] intermediate disproportionation route to chlorine dioxide becomes less important (eq. 48), and the route to chlorite formation by hydrolysis predominates as does the reaction with any available excess HOCl to form chlorate and chlorine ... 

A major disadvantage of this system is the limitation of the single-pass gas-chlorination phase. Unless increased pressure is used, this equipment is unable to achieve higher concentrations of chlorine as an aid to a more complete and controllable reaction with the chlorite ion. The French have developed a variation of this process using a multiple-pass enrichment loop on the chlorinator to achieve a much higher concentration of chlorine and thereby quickly attain the optimum pH for maximum conversion to chlorine dioxide. By using a multiple-pass recirculation system, the chlorine solution concentrates to a level of 5-6 g/1. At this concentration, the pH of the solution reduces to 3.0 and thereby provides the low pH level necessary for efficient chlorine dioxide production. A single pass results in a chlorine concentration in water of about 1 g/1, which produces a pH of 4 to 5. If sodium chlorite solution is added at this pH, only about 60 percent yield of chlorine dioxide is achieved. The remainder is unreacted chlorine (in solution) and... 

Chlorine dioxide can be formed out of the chlorite by either of the reactions described by Equation 25.3 or 25.8. Equation 25.1 describes the chlorite formation. The chlorine concentration in the liquid is normally very low as the reaction with caustic (Equation 25.4) is very fast. The concentration of chlorine and/or hypo-chlorous acid HOCl can increase on depletion of hydroxide ions in the liquid. As in step two of the hypochlorite unit, the caustic concentration is in the order of 4-10 g l-1 and it is possible to conclude that at the gas-liquid interface the concentration might be quite low owing to the fast reaction with chlorine. 

Oxidizers may not themselves be combustible, but they may provide reaction pathways to accelerate the oxidation of other combustible materials. Combustible solids and liquids should be segregated from oxidizers. Certain oxidizers undergo dangerous reactions with specific noncombustible materials. Some oxidizers, such as calcium hypochlorite, decompose upon heating or contamination and self-react with violent heat output. Oxidizers include nitrates, nitric acid, nitrites, inorganic peroxides, chlorates, chlorites, dichromates, hypochlorites, perchlorates, permanganates, persulfates and the halogens. 

Like chlorine dioxide, chlorite is a very reactive compound. Since chlorite is an ion, it vrill not exist in air. In water, chlorite ions will be mobile and may move into groundwater. However, reaction with soils and sediments may reduce the concentration of chlorite ions capable of reaching groundwater. For additional information about what happens to chlorine dioxide and chlorite when they enter the environment, see Chapter 6. 

Metabolism. Although no information was located regarding mechanisms of chlorine dioxide and chlorite metabolism, ultimate transformation to chloride ions is likely achieved via redox reactions with a variety of substances in biological systems that are readily oxidized. 

Because chlorite is an anion, sorption of chlorite ions onto suspend particles, sediment, or clay surfaces is expected to be limited under enviromnental conditions. Thus, chlorite ions may be mobile in soils and leach into groundwater. However, chlorite (ions or salts) will undergo oxidation-reduction reactions with components in soils, suspend particles, and sediments (e.g., Fe, Mn ions see Section 6.3.2.2). Thus, oxidation-reduction reactions may reduce the concentration of chlorite ions capable of leaching into groundwater. 

Nicoson JS, Margerum DW. 2002. Kinetics and mechanisms of aqueous chlorine reactions with chlorite ion in the presence of chloride ion and acetic acid/acetate buffer. Inorg Chem 41(2) 342-347. 

Reaction with sodium hydroxide in the presence of carbonaceous matter and lime produces sodium chlorite. 

Being a strong oxidizing agent, its reactions with reducing agents or oxidizable substances can be violent to explosive. Under controUed conditions, it can be combined with many metals to obtain their chlorite salts. 

Benzo[ ]perimidinone carbaldehyde and carboxylic acid derivatives have also been prepared by alkyl oxidation. Thus, treatment of the 2-methyl derivative 588 with selenium dioxide at reflux in dioxane gave the aldehyde 589, which then gave carboxylic acid 590 on reaction with sodium chlorite <2001JME2004>. 

In all four cases, we have strong experimental evidence for two distinct reactions with chlorite. One of these reactions corresponds to the oxidation of the metal ion by chlorite, followed by the rapid formation of chlorate. Another interesting point is that the relative order of rate of metal ion plus halogenate is found to be ... 

G. S. Serullas treated potassium chlorate with an excess of hydrofluosilicic acid the clear liquid was decanted from the sparingly soluble potassium fluosilicate, the soln. evaporated below 30°, and filtered through glass powder J. J. Berzelius evaporated the acid liquid mixed with finely divided silica below 30° in air, or over cone, sulphuric acid and potassium hydroxide in vacuo. The excess of hydrofluoric acid was volatilized as silicon fluoride, and the clear liquid was then filtered from the excess of silica. R. Bottger treated sodium chlorate with oxalic acid whereby sparingly soluble sodium oxalate was formed J. L. Wheeler, and T. B. Munroe treated sodium chlorate with hydrofluosilicic acid and M. Brandau treated potassium chlorate with aluminium sulphate and sulphuric acid and precipitated the alum so formed with alcohol. Chloric acid is formed in many reactions with hypochlorous and chlorous acid for example, it is formed when an aq. soln. of chlorine or hypochlorous or chlorous acid decomposes in light. It is also formed when an aq. soln. of chlorine dioxide stands in darkness or in light. A mixture of alkali chlorate and chlorite is formed when an aq. soln. of an alkali hydroxide is treated with chlorine dioxide. 

Zinc forms a wide variety of other salts, many by reaction with the adds, though some can only be obtained by fusing the oxides together. The salts include arsenates (ortho, pyro, and meta), the borate, bromate, chlorate, chlorite, various chromates, cyanide, iodate. various periodates, permanganate, phosphates (ortho, pyro, meta, various double phosphates 1. die selenate, selenites, various silicates, fluosilicate. sulfate, sulfite, and duocyanate. 

Chlorite is known in two forms NaC102 and NaC102.3 HzO. The powder is completely stable, if stored in a dry place and at a normal temperature. When heated up to 150 to 200 °C, it decomposes mainly into chlorate and chloride and to a lesser extent into oxygen and chloride. Chlorite is more stable than hypochlorite, but less stable than chlorate. Its reaction with sulphur is spontaneous. It is, therefore, imperative to prevent chlorite from coming into contact with rubber which had been vulcanized with sulphur. 

So formed, chlorine dioxide may undergo many chemical or electrochemical reactions. With organic matter it again forms chlorite. If ozone is generated, it reacts in the ms-range with chlorine dioxide in competition with the reaction with active chlorine (Gordon et al. 2002) ... 

The oxidation pathways of chlorine dioxide under actual conditions are complex because a number of species including chlorine, hypochlorous, chlorous, and chloric acids are formed as intermediates. A rapid conversion of chlorine dioxide to chloride and chlorite (chlorous acid, pK 2.0) may first take place, followed then by a slow phase during which mainly the chlorite reacts with the pulp components. However, continuous generation of chlorine dioxide during bleaching takes place, for example, by the reaction between chlorite and chlorine (or hypochlorous acid) ... 

DOT CLASSIFICATION 5.1 Label Oxidizer SAFETY PROFILE A strong oxidizer. Ignites on contact with potassium thiocyanate. Reaction with CI2 yields explosive CIO2. When heated to decomposition it emits toxic fumes of CT. See also CHLORITES and CALCIUM COMPOUNDS. 

Chlorite reacts with molecular chlorine and with hypochlorous acid at comparable rates , reactions (15)-(17),... 

In a semi-quantitative stopped-flow study, based only on yields of chlorine dioxide, (15) was found to be faster than (16), with (17) always occurring but of most significance for low concentrations of chlorous acid. With excess sodium chlorite, the yield of chlorine dioxide could be in excess of that predicted by (15) so that catalysis (by CI2 or by HCIO) of a chlorite reaction seems probable. Reactions (15) and (16) are both approximately second order. The mechanism, suggested to be consistent with Dodgen and Taube s results , involves the steps... 

The reaction with iodide has been examined using a rapid-mixing device . Two slow steps were detected in the pH range 5.5-8.S. The first may be ascribed to formation of the species CIO2I and the second to its decomposition, yielding chlorite and iodine. Both reactions have small activation enthalpies, 7.4 and 0.8 kcal.mole , respectively. The intermediate is probably related closely to the species CI2O2 previously proposed (p. 376). 

Chlorine dioxide is a relatively stable free radical it is paramagnetic because it contains an unpaired electron. It can be prepared by oxidizing chlorite, 0102", for example, by peroxosulfate or CI2. The reaction with CI2 is... 

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