Chlorides electrooxidation

Using a fluidized bed electrode, this process was studied by Jircny 1985 [118]. Jircny [119] worked with a laboratory scale cell and subsequently a pilot plant. The pilot plant was designed to produce one ton of D-arabinose per year. The electrochemical reactor was 0.3 x 0.6 x 0.6 m and contained five 225 A cells in series. A major advantage of the electrooxidation over the usual chemical route (oxidation with sodium perchlorate) was the ease of separation of D-arabinose from the reactor outflow. In chemical routes, the separation is made difficult by the presence of large amounts of sodium chloride. 

Electrochemical epoxidation of olefins has been developed for the production of ethylene and propylene oxides in aqueous sodium chloride or bromide solution. However, associated with these electrolyses are difficulties in achieving product selectivity as well as in obtaining high yields of the epoxides. Recently, a regiose-lective )-epoxidation of polyisoprenoids (23) to (24), promoted by electrooxidation in an MeCN/THF/H20-NaBr-(Pt) system, has been achieved (Scheme 10) [52]. 

Formation of the P—N bond has been observed when the cross-coupling of dialkylphosphites (59) with amines (60) proceeds by an iodo cation [I]+-promoted electrooxidation, affording N-substituted dialkylphosphor-amidates (61) (Scheme 22) [76]. Lack of alkali iodide in the electrolysis media results in the formation of only a trace of (61), indicating that the iodide plays an important role in the P—N bond-forming reaction. In contrast, usage of sodium bromide or sodium chloride brings about inferior results since the current drops to zero before the crosscoupling reaction is completed. 

Thin-layer Studies. The thin-layer electrochemical system was developed to address the lack of sensitivity of a preliminary bulk amperometric activity assay (77). The first set of thin-layer studies was taken to characterize the thin-layer cells in soluble enzyme solutions and to determine if there were any interferences to the detection of hydrogen peroxide. Preliminary thin-layer studies (23) indicated that the oxidation of hydrogen peroxide could be detected at approximately 1080 mV with only minimal interference from the oxidation of glucose by gold. The addition of chloride ion to the solution further suppressed the glucose electrooxidation interference. 

Anodization — Formation of a film on an electrode by means of an anodic (oxidation) process. Electrooxidation of silver in a chloride-containing solution results in the formation of an AgCl-film because the solubility product of AgCl is rapidly surpassed upon oxidation of silver. The AgCl-coated silver is suitable for preparation of a Ag/AgCl -> reference electrode. Formation of an oxide layer on other metals (e.g., in case of aluminum) may result in improved surface properties (corrosion resistance, hardness, optical properties). 

Kimura, M., Kobayashi, K., Yamamoto, Y., Sawaki, Y. Electrooxidative pinacol-type rearrangement of f3-hydroxy sulfides. Efficient C-S cleavage mediated by chloride ion oxidation. Tetrahedron 1996, 52,4303-4310. 

The selectivity of palladium and gold for alkene oxidation to aldehydes 28,29,170) was attributed initially to adsorption strength. However, electrooxidation in the presence of palladium ions indicates possible homogeneous alkene insertion, similar to the Wacker process 304). Homogeneous reaction is also involved in redox oxidations of hydrocarbons. In this case, the nature of the metal ions is expected to control selectivity. Indeed, toluene yields 20% benzaldehyde in electrolytes containing Ce salts, while oxidation proceeds to benzoic acid with Cr redox catalysts 311). In addition, the concentration of redox catalysts appears to affect yields in nonelectrochemical oxidation of ethylene large amounts of palladium chloride promote butene formation at the expense of acetaldehyde 312). Finally, the role of the electrolyte and solvent should not be ignored. For instance, electrooxidation of ethylene on carbon, in aqueous solution of acetic acid yields acetaldehyde 313) in the... 

Plication of compounds ()Qn)-(XXII) and conversion from a cation Z to an other Z, or from a metal to another one, can be performed by a three-step se-quence treatment with benzoyl chloride, reaction with sodium ethoxide and treatment with a transition metal t in presence of ZBr or Z Br. All the compounds of the type (Xni)-(XXII) can be transformed to the corresponding neutral compounds (x=0) after treatment widi an oxidizing reagent (e.g. Bt2) or by electrooxidation. 

General Electrochemical Setup. Catalytic studies to probe formic acid electrooxidation efficiencies are commonly not performed in a complex fuel cell, but using a three-electrode electrochemical cell at room temperature, consisting of a working (catalyst of interest), a counter (Pt mesh), and a reference electrode. Potentials are typically referenced against an RHE, saturated calomel electrode (SCE), or sUver/silver chloride (Ag/AgCl). 

Jou LH, Chang JK, Whang TJ, Sun IW (2010) Electrodeposition of Palladium-Tin alloys from l-ethyl-3-methylimidazolium chloride-tetrafluoroborate ionic liquid for ethanol electrooxidation. J Electrochem Soc 157 D443-D449... 

Chemistry may be combined with CPC to improve selectivity. For example (Jackson et al. 1980) applying the chemistry of the Davies and Townsend titration (seeO Sect. 63.4.4.3), Pu is first reduced electrolytically to Pu(III) in an hydrochloric/sulfamic acid mixture along with iron and other potential interfering species. Iron and a number of the other impurities are reoxidized next without reoxidizing Pu(in). Finally, phosphate is added to lower the redox potential of the Pu(III)/Pu(IV) couple to permit a quantitative electrooxidation of Pu(III) to Pu(IV), without oxidizing chloride ions. The procedure is very selective and is applicable to Pu determinations in the presence of uranium in 10 1 U/Pu molar ratio. 

The solubility of polymers depends on their ionic state. Electrooxidized polymers such as poly(vinylferrocene) (//) were found to deposit on the anode due to the poor solubility of the oxidized polymer in the solvent used Photooxidized poly(vinyl-ferrocene) was precipitated from methylene chloride solution by photooxidation... 

Tomcsanyi L, De Battisti A, Hirschberg G, Varga K, Liszi J. The study of the electrooxidation of chloride at Ru02/Ti02 electrode using CV and radiotracer techniques and evaluating by electrochemical kinetic simulation methods. Electrochim Acta 1999 44 2463-72. 

Melt Salts and Solid-State Polymerization. By using a chloroalu-minate melt obtained from a mixture of iV-acetylpyridinium chloride or Af-butylpyridinium chloride and AICI3 at room temperature, highly conducting poly(p-phenylene) films were obtained by electrooxidation of benzene on Ft [368-371]. 

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