Oxidation by hypochlorite

Fatty acids are prepared by acylating thiophene with acid chlorides and reducing the ketones (218) to alkylthiophenes according to Wolff-Kishner or Clemmensen. The latter are then acetylated and oxidized by hypochlorite to 5-alkyl-2-thiophenecarboxylic acids, > ... 

Iron(Il) hydrogen phosphite, FeHPO, is oxidized by hypochlorite ions in basic solution. The products are chloride ion, phosphate ion, and iron(lll) hydroxide. Write the balanced equation for each half-reaction and the overall equation for the reaction. 

Decomposition Pyrolysis occurs at 170°C after prolonged periods yielding CO, COz, benzophenone, and benzhydrol appreciable hydrolysis in acidic or basic solutions occurs yielding 3-quinuclidinol and benzilic acid BZ is oxidized by hypochlorite at a pH of 1-13. 

Oxidation of triazine herbicides with chlorine and chlorine dioxide has been widely studied [105-108]. In the case of sulfur-containing triazines, oxidation occurs mainly via cleavage of the weakened R-S-CH3 bond rather than by addition of chlorine. Reactions of S-triazines with chlorine are faster than with chlorine dioxide, and form sulfoxide, sulfone, and a sulfone hydrolysis product. Chlorination with chlorine dioxide only produced sulfoxide [108]. Lopez et al. identified the formation of sulfonate esters during the chlorination of ametryn and terbutryn [106, 107]. Triazine DBFs identified by Brix et al. exhibited higher toxicities than the parent compounds [105]. Similar to triazines, clethodim, a cyclohexanedione herbicide, is oxidized by hypochlorite and chloramines to clethodim sulfoxide and then to sulfone [109]. 

Dinitrocresols present in water samples, especially when present at low concentrations, can be lost via oxidation by hypochlorite (Di Corcia and Marchetti 1992). This can be eliminated through the addition of sodium sulfite prior to extraction. In the multiresidue method of Chen et al. (1991), Mn + dissolved in the sample would be oxidized to manganese(lll,IV) oxides during base extraction, which in turn would oxidize the phenols during acid extraction. The oxidation of phenols can be eliminated by adding sodium thiosulfate to the sample prior to extraction or extraction at acidic pH as the first step, providing that manganese(lll,IV) oxides are not present in the sample before extraction. 

CO2 and N2. Excess chlorine gas (i.e., chlorine which did not form hypochlorite) converted the cyanide to cyanate, which was subsequently oxidized by hypochlorite. Cadmium was precipitated from the water due to an increase in the solution pH. A platinum-plated niobium screen was the anode and a stainless steel screen was used as the cathode. At an applied potential of 6.0 V, resulting in a current of 6.0 A, the cadmium concentration decreased from 17.4mg/dm to 0.01 mg/dm, while the cyanide concentration declined from 54 mg/dm to zero in 80 min of cell operation. 

In the section entitled Cleaning Up at the end of each experiment the goal is to reduce the volume of hazardous waste, to convert hazardous waste to less hazardous waste, or to convert it to nonhazardous waste. The simplest example is concentrated sulfuric acid. As a by-product from a reaction, it is obviously hazardous. But after careful dilution with water and neutralization with sodium carbonate, the sulfuric acid becomes a dilute solution of sodium sulfate, which in almost every locale can be flushed down the drain with a large excess of water. Anything flushed down the drain must be accompanied by a large excess of water. Similarly, concentrated base can be neutralized, oxidants such as Cr " can be reduced, and reductants such as hydrosulfite can be oxidized (by hypochlorite— household bleach). Dilute solutions of heavy metal ions can be precipitated as their insoluble sulfides or hydroxides. The precipitate may still be a hazardous waste, but it will have a much smaller volume. 

Levy, J.N., and McKenna, C.E., Oxidations of triethyl a-phosphonoacrylate. Epoxidation to triethyl a-phosphonoacrylate oxide by hypochlorite and formation of triethyl dihydroxyphosphonoacetate with RuO4-periodate, Phosphorus, Sulfur Silicon Relat. Elem., 85, 1, 1993. 

The separation of ammonia from interfering compounds was also based on gaseous diffusion of ammonia from an alkaline medium and absorption by an acidic medium. Walker and Shipman described the isolation of ammonia by the use of a zirconium phosphate cation exchanger. The adsorbed ammonia was displaced from the column by 1.24 M cesium chloride, then oxidized by hypochlorite, reacted with phenol to form a phenol-indophenol complex which was measured at 395 or 625 nm, depending on the concentration range. 

This clearly establishes the chemical feasibility of gold oxidation by hypochlorite and provides a plausible mechanism for the findings of Gleichmann and Verwilghen. ... 

In cyclohexane oxidation by hydrogen peroxide and hypochlorite in the presence of 4-dimethylaminopyridine, poly(acrylamide)s containing phthalocya-nine groups were used. Oxidation for 22 h by hydrogen peroxide gave 1,2-dihydrocyclohexane with 43% yield, and oxidation by hypochlorite gave 1,2-dihydrocyclohexane with 79% yield and l-hydroxy-2-chlorocyclohexane with 11% yield. The catalyst had high catalase activity [88-90]. 

However, these hypochlorite studies have been criticized on the basis of the claim that sodium hypochlorite only oxidize sjp carbon under the reaction conditions. For example, there is the claim that coal oxidation, by sodium hypochlorite under rigidly controlled experimental conditions, produces data which show that aromatic systems also undergo oxidation by hypochlorite. Thus, there are legitimate question about the occurrence of adamantane-type systans in coal. It is suggested that the main structural unit of bituminous coal is a three-dimensional cross-linked systan (Mayo, 1975 Lucht and Peppas, 1981) which contains condensed aromatic, as well as aUcycUc, systems that are connected by ether (or thioether) linkages as well as by methylene (or polymethylene) linkages. 

Small quantities of thiols (mercaptans) and sulfides can be destroyed by oxidation to a sulfonic acid with sodium h5q)ochlorite. If other groups that can be oxidized by hypochlorite are also present, the quantity of this reagent used must be increased accordingly. 

An occasional and usually sporadic problem with acidified brine is the formation of insoluble material at pH values of less than 4.5. This appears as fine particles, known as brine rocks, that often plug the brine rotameters. The problem can be avoided by using alkaline brine or by chlorinating the treated brine before acidification. The latter technique depends on the fact that the precursors of the brine rocks appear to be oxidized by hypochlorite in alkaline solution. 

A few transition metals catalytically destroy hypochlorite. Hypochlorite oxidizes these metals to form intermediates that oxidize water to liberate oxygen. This returns the metal to its original oxidation state, thus it is again oxidized by hypochlorite. The overall reaction is as follows ... 

EXERCISE 14 Iodide ion is oxidized by hypochlorite ion in basic solution. 

A test for the detection of excess indican in urine based on its oxidation by hypochlorite to indigo blue which is extracted into chloroform. 

ArNHNHCONHa). These compounds are first oxidized by hypochlorite to aryl diazocarboxamides... 

RDE Refining of Cyanide Industriai Wastewaters Cyanides are used in many industrial processes such as surface treatment and noble metal plating. After several cycles the baths must be renewed in order to maintain the same operating conditions. The conventional physicochemical process applied to eliminate cyanide from liquid effluents is mainly oxidation by hypochlorite or ozone. Depleted wastewaters contain O.lmg/L of free cyanide and may be rejected into the environment. The new environmental regulations are more restrictive and concern both free and total cyanide. RDE technology was applied in order to reduce both free and complexed cyanide levels. 

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