Chloride electrochemical oxidation

As a possible strategy to avoid chlorinating side reactions by cupric chloride, electrochemical oxidation ofthe Pd(0) has been claimed [48,49]. 

A -Pyrazolines such as (410) are oxidized by iodine, mercury(II) acetate and trityl chloride to pyrazolium salts (411), and compound (410) even reduces silver nitrate to Ag° (69JOU1480). Electrochemical oxidation of l,3,5-triaryl-2-pyrazolines has been studied in detail (74BSF768, 79CHE115). They Undergo oxidative dimerization and subsequent transformation into the pyrazole derivative (412). 

By the way, trifluoroacetaldehyde is a versatile fluoro building block. However the chemical or electrochemical oxidative transformation of trifluoro-ethanol to trifluoroacetaldehyde has been unsuccessful. Trifluoroacetaldehyde is therefore generally produced by the reduction of trifluoroacetic acid ester or acid chloride using an excess of LAH. The anodic substitution at fluoroaikyl phenyl sulfides is a useful alternative because it realizes the transformation of economical trifluoroethanol to highly valuable trifluoroacetaldehyde equivalents as shown in Scheme 6.5. 

Electrochemical oxidation-reduction of eluting mixture components is the basis for amperometric electrochemical detectors. The three electrodes needed for the detection, the working (indicator) electrode, reference electrode, and auxiliary electrode, are either inserted into the flow stream or imbedded in the wall of the flow stream. See Figure 13.13. The indicator electrode is typically glassy carbon, platinum, or gold, the reference electrode a silver-silver chloride electrode, and the auxiliary a stainless steel electrode. Most often, the indicator electrode is polarized to cause oxidation of the mixture components... 

Electrochemical oxidation of aldoximes using halide ions as mediators afforded the corresponding nitrile oxides in the anode compartment, which were simultaneously reduced to nitriles by cathodic reduction (equation 15). Sodium chloride affords the best result among the supporting electrolytes (Cl > Br > 1 > C104 > TsO ). Accordingly, the electrochemical reaction of oximes carried out in the presence of dipolephiles yielded isooxazolines (equation 16). 

Zirconium(IV) and hafnium(IV) chlorides and bromides form 1 2 adducts of the type [ZrX4(RCN)2] (R = Me, Et, Pr or Ph X = Cl or Br) and [HfX4(MeCN)2] (X = Cl or Br).11SM24 These complexes may be prepared by (i) direct reaction of the metal tetrahalide with an excess of the nitrile120 123 or (ii) electrochemical oxidation of zirconium or hafnium metal in the presence of a solution of chlorine or bromine in acetonitrile.118 The adducts are moisture-sensitive, white solids, insoluble in nonpolar solvents, but soluble in acetonitrile. In the later solvent, [ZrBr4(MeCN)2 behaves as a nonelectrolyte.122... 

The electrochemical oxidation of isobutyraldehyde98 and acetaldehyde99 in methanol-ammonia, containing lithium chloride, yields s-triazines through formation of an iminomethoxy adduct, RC(=NH)OCH3, followed by trimerization with liberation of methanol. No s-triazine is obtained from formalin, and benzaldehyde gives only a 1% yield of s-triazine. Cyana-mide has also been oxidized at a platinum anode in aqueous potassium hydroxide.100 The oxidation products consisted of several known products,... 

A different route to pyrones is the preparative electrochemical oxidation of enamines in acetonitrile in the presence of tetraethylammonium perchlorate (88MI2) (Scheme 46). The synthesis of 2-pyrone derivatives has been carried out by reaction of /3-dicarbonyl compounds with methyl-a-benzoylamino-/3-dimethylaminoacrylate (96JHC751). Thiapyran derivatives can be obtained by interaction of enamines based on (/3-amino-a-cyanoacryloylmethyl)pyridinium chloride derivatives with carbon disulfide (95M711).The synthesis of pyridine derivatives based on analogous enamines has been described as well (95M711). 

Hall SB, Khudaish EA, Hart AL. Electrochemical oxidation of hydrogen peroxide at platinum electrodes. Part V. Inhibition by chloride. Electrochimica Acta 45, 2000, 3573-3579. 

The direct electrochemical oxidation (no cell divider membrane) of wastewater has been employed in the textile industry. Typically, this industry produces an organic-contaminated wastewater that also contains sodium chloride sodium chloride is desirable in promoting anodic oxidation. The presence of sodium chloride is fortuitous for textile manufacturers since the hypochlorite byproduct produced in the electrochemical oxidation process is used for textile bleaching operations.24... 

We used the radical relay process, chlorinating C-9 and then generating the 9(11) double bond, in a synthesis of cortisone 91 [158]. This is a substitute for manufacturing processes in which C-9 or C-ll are hydroxylated by biological fermentation. Also, with templates that directed the chlorination to C-17 of 3a-cholestanol, such as that in 90, we were able to remove the steroid sidechain [159-162]. Using an electrochemical oxidation process, we could direct chlorination by simple chloride ion with an iodo-phenyl template [163]. A general review of the processes with iodophenyl templates has been published [164]. 

It follows from the above explanation that electrolysis of alkali chlorides in an electrolyzer without a diaphragm must be interrupted before curve h which represents the concentration of hypochlorite oxygen changes into a horizontal line only under this condition is the process economical, as a prolonged electrolysis would result in a waste of current without any further increase in th<) hypochlorite content. Moreover, care should be taken to prevent the hypochlorite ions formed from being electrochemically oxidized, as this would result in lower current efficiency and lower hypochlorite concentration in the liquor produced. This process is influenced by a number of factors, e. g. brine concentration, hydrogen ion concentration, anode material, current density, temperature, and last but not least a suitable design of the electrolyzer. 

On calculating the anode potential we assume that hypochlorite is formed directly by the electrochemical oxidation of chloride according to the equation which results from equations (XI1I-4) and (X11T-5) ... 

When describing the manufacture of hypochlorites, wc have stated the conditions under which chlorates can be formed in the course of the electrolysis of neutral solutions of alkali chlorides. We have shown that smooth platinum is the most suitable anode material, ensuring with neutral solutions the highest yields of chlorate, i. e. 66.67 per cent. Under this condition the chlorate is almost exclusively formed by electrochemical oxidation ... 

During the electrochemical oxidation of chloride, chlorate is formed in accordance with the equation ... 

Charge-transfer complexes of dicyclopenteno 1,4,5,8-tetratellurafulvalene with a variety of donors such as tetracyanoquinodimethane were prepared7. By electrochemical oxidation cation radical salts with chloride, bromide, iodide, hexafluorophosphate, or hexaflu-oroarsenate as anions were obtained8. 

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