Water electrolytic reduction

Europium(TTI) salts are typical lanthanide derivatives. Europium(ll) salts are pale yellow in colour and are strong reducing agents but stable in water. EuX2 are prepared from EuX -hEu (X=C1, Br, I) or EuFa + Ca EuCl2 forms a dihydrale. EUSO4 is prepared by electrolytic reduction of Eu(III) in sulphuric acid. Eu(II) is probably the most stable +2 stale of the lanthanides... 

Reduction of vanillin by means of platinum black in the presence of ferric chloride gives vanillin alcohol in excellent yields. In 1875, Tiemann reported the reduction of vanillin to vanillin alcohol by using sodium amalgam in water. The yields were poor, however, and there were a number of by-products. High yields of vanillin alcohol have been obtained by electrolytic reduction. 

Tetrahydrostrychnine, CgjHggOgNg. HgO. This substance, also formed by the electrolytic reduction of strychnine, crystallises from alcohol in prisms, m.p. 202°, gives colour reactions of the strychnidine type, and yields both neutral and acid salts the hydrochloride, B. HCl, occurs in small needles readily soluble in water and the dihydriodide, B. 2HI. 2HjO, in pyramidal crystals. The base yields an amorphous nitrosoamine, the hydrochloride of which crystallises from warm water in lustrous, yellowish prisms. It also furnishes a crystalline monoacetyl derivative, and on heating with hydrochloric acid or phosphorus oxychloride is dehydrated to strychnidine. 

The coordination chemistry in this oxidation state is essentially confined to the ions Sm", Eu and Yb . These are the only ones with an aqueous chemistry and their solutions may be prepared by electrolytic reduction of the Ln " solutions or, in the case of Eu", by reduction with amalgamated Zn. These solutions are blood-red for Sm", colourless or pale greenish-yellow for Eu" and yellow for Yb", and presumably contain the aquo ions. All are rapidly oxidized by air, and Sm" and Yb" are also oxidized by water itself although aqueous Eu" is relatively stable, especially in the dark. 

About 250 ml of a reaction mixture obtained by the electrolytic reduction of nitrobenzene in sulfuric acid solution and containing about 23 grams of p-aminophenol by assay is neutralized while at a temperature of 60° to 65°C, to a pH of 4.5 with calcium carbonate. The calcium sulfate precipitate which forms is filtered off, the precipitate washed with hot water at about 65°C and the filtrate and wash water then combined. The solution is then extracted twice with 25 ml portions of benzene and the aqueous phase is treated with 0.5 part by weight, for each part of p-aminophenol present, of activated carbon and the latter filtered off. The activated carbon is regenerated by treatment with hot dilute caustic followed by a hot dilute acid wash, and reused a minimum of three times. 

Cobalt(II) complexes of three water-soluble porphyrins are catalysts for the controlled potential electrolytic reduction of H O to Hi in aqueous acid solution. The porphyrin complexes were either directly adsorbed on glassy carbon, or were deposited as films using a variety of methods. Reduction to [Co(Por) was followed by a nucleophilic reaction with water to give the hydride intermediate. Hydrogen production then occurs either by attack of H on Co(Por)H, or by a disproportionation reaction requiring two Co(Por)H units. Although the overall I easibility of this process was demonstrated, practical problems including the rate of electron transfer still need to be overcome. " " ... 

The authors found that the water content of the system was important, as can be seen from Figure 3.54(a) which shows the volume of CO produced after 4h of electrolysis as a function of the percentage of added water, the maximum yield being obtained for the electrolyte having 10% added water. In the absence of water, the reduction occurred much more slowly and an orange species accumulated in solution, disappearing slowly when the current was switched off. 

Phenylacetamide has been obtained by a wide variety of reactions from benzyl cyanide with water at 250-260° 6 from benzyl cyanide with water and cadmium oxide at 240° 6 from benzyl cyanide with sulfuric acid 7 8 by saturation of an acetone solution of benzyl cyanide with potassium hydrosulfide 9 from benzyl cyanide with sodium peroxide 10 by electrolytic reduction of benzyl cyanide in sodium hydroxide 11 from ethyl phenyl-acetate with alcoholic 12 or aqueous 13 ammonia from phenyl-acetic acid with ammonium acetate 14 or urea 15 from diazoacetophenone with ammoniacal silver solution 16 from phenyl-acetic acid imino ether hydrochloride and water 17 from acetophenone with ammonium poly sulfide at 215° 18 from benzoic acid 19 and by heating the ammonium salt of phenyl-acetic acid.20... 

Hypovanadous oxide resembles the metal in many of its properties. It is insoluble in water, but dissolves in acids without evolution of hydrogen to yield the lavender-coloured solutions which are characteristic of solutions of hypovanadous salts. These salts are, however, most conveniently prepared in solution by electrolytic reduction in an inert atmosphere of solutions of vanadium pentoxide in the various acids.7 Hypovanadous salts are isomorphous with salts of divalent iron, chromium, and manganese. On being treated with caustic alkalis, a brown precipitate of hypovanadous hydroxide, V(OH)a, is obtained, which rapidly oxidises to the greyish-green vanadous hydroxide, V(OH)s. 

Niobium Trichloride, NbCl3, is prepared by leading the vapour of niobium pentachloride through a heated tube.4 It is also formed in small quantity by the action of carbon tetrachloride vapour on niobium pentoxide contained in a hard-glass tube, and has probably been prepared in solution by the electrolytic reduction of the pentachloride.4 It forms a black, crystalline crust with an almost metallic lustre, which closely resembles the appearance of a film of sublimed iodine. It is not decomposed by water or ammonia, but is readily oxidised by dilute nitric add to niobium pentoxide. On being heated to a red heat in an atmosphere of carbon dioxide, a sublimate of niobium oxytrichloride, NbOCl3, is produced, the carbon dioxide undergoing reduction to the monoxide. 

The chemical reactions of organic molecules at excited semiconductor electrodes are of course reduction and oxidation processes, but these depend on the solvents and other reactants such as water, electrolytes and molecular oxygen. Figure 4.69 gives a few examples of many such reactions which are finding applications in chemical synthesis. 

Nitrosorbite (Sorbitol hexanitrate) d-Sorbite occurs in the berries of the mountain ash, but is more readily procured by the electrolytic reduction of d-glucose. It crystallizes with one molecule of water in small crystals which lose their water when heated and melt at about 110°. Nitrosorbite, isomeric with nitromannite, exists as a viscous liquid and has never been obtained in the crystalline state. It is used in non-freezing dynamites. 

A 1-g. sample is dissolved in concentrated nitric acid, the resulting iodine removed by filtration through a sintered-glass funnel, washed with water, and the washings added to the yellow filtrate. The latter is diluted with water and the copper determined by electrolytic reduction. Anal. Calcd. for Cul Cu, 33.4. Found Cu, 33.1. 

Aluminum is present in most rocks and is the most abundant element in the earth s crust (eight percent by weight.) However, its isolation is very difficult and expensive to accomplish by purely chemical means, as evidenced by the high E° (-1.66 v) of the A13+/A1 couple. For the same reason, aluminum cannot be isolated by electrolysis of aqueous solutions of its compounds, since the water would be electrolyzed preferentially. And if you have ever tried to melt a rock, you will appreciate the difficulty of electrolyzing a molten aluminum ore Aluminum was in fact considered an exotic and costly metal until 1886, when Charles Hall (U.S.A) and Paul Herault (France) independently developed a practical electrolytic reduction process. 

Q10 Pancreatic insufficiency occurs in approximately 80% of cystic fibrosis patients. There is a marked reduction in the water, electrolyte and enzyme content of pancreatic secretion. Because of deficient digestive enzymes, there is inadequate digestion and absorption of nutrients and some nutritional deficiency occurs. 

The pure, anhydrous nitrite is not hygroscopic, but as usually prepared the substance is a very deliquescent, crystalline solid, its aqueous solution having a slight alkaline reaction. At 15-5° C. the solubility is 300 grams per 100 grams of water.11 The heat of formation in aqueous solution from the elements is 88-9 Cal.12 The products of electrolytic reduction are hyponitrite, ammonia, and hydroxylamine. 

The first transition metal cation which is unstable in water but which can be generated as a stable entity in HF was U3+ [30]. It was formed by oxidation of the metal by protons in a BF3-HF solution which is non-oxidising and relatively weakly acidic. The UV-vis spectrum of the lilac-colored solution was virtually identical with that observed for an acidified aqueous solution in which the uranium solution was under continuous electrolytic reduction to maintain U(III) as the aquo-cation. 

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