Hydrogen electrolytic reduction

The reduction of pteridines to the 7,8-dihydropteridine system is the most common reaction as the 7,8-dihydro system is the most thermodynamically stable dihydropteridine. A wide range of reagents may be used for this transformation including catalytic hydrogenation, electrolytic reduction, and the use of reagents such as sodium dithionite, sodium (and potassium) borohydride, zinc dust in alkali, Raney nickel, and sodium amalgam in water.18... 

Hydroxylamine is derived from ammonia by replacing one hydrogen atom by a hydroxyl group. It is prepared by the electrolytic reduction of nitric acid, using a lead cathode ... 

Reduction. These hydroxybenzaldehydes can be reduced by catalytic hydrogenation over palladium or platinium to yield the corresponding hydroxybenzyl alcohols, but the electrolytic reduction in an alkaline medium gives the coupling product l,2-bis(4-hydroxyphenyl)ethane-l,2-diol in very good yield from 4-hydroxybenzaldehyde (49—51). 

It is easy to reduce anhydrous rare-earth hatides to the metal by reaction of mote electropositive metals such as calcium, lithium, sodium, potassium, and aluminum. Electrolytic reduction is an alternative in the production of the light lanthanide metals, including didymium, a Nd—Pt mixture. The rare-earth metals have a great affinity for oxygen, sulfur, nitrogen, carbon, silicon, boron, phosphoms, and hydrogen at elevated temperature and remove these elements from most other metals. 

Glycohc acid [79-14-1], HOOCCH2OH, mol wt 76.05, can be obtained by the electrolytic reduction of oxaUc acid or the catalytic reduction of oxaUc acid with hydrogen in the presence of a mthenium catalyst. Because of its acidity it is used as a cleaning agent for metal surface treatments and for boiler cleaning. It also serves as an ingredient in cosmetics (qv). 

Aminophenols are either made by reduction of nitrophenols or by substitution. Reduction is accompHshed with iron or hydrogen in the presence of a catalyst. Catalytic reduction is the method of choice for the production of 2- and 4-aminophenol (see Amines BY reduction). Electrolytic reduction is also under industrial consideration and substitution reactions provide the major source of 3-aminophenol. 

Sodium nitrite has been synthesized by a number of chemical reactions involving the reduction of sodium nitrate [7631-99-4] NaNO. These include exposure to heat, light, and ionizing radiation (2), addition of lead metal to fused sodium nitrate at 400—450°C (2), reaction of the nitrate in the presence of sodium ferrate and nitric oxide at - 400° C (2), contacting molten sodium nitrate with hydrogen (7), and electrolytic reduction of sodium nitrate in a cell having a cation-exchange membrane, rhodium-plated titanium anode, and lead cathode (8). 

On hydrogenation at 80°, or on electrolytic reduction, aphyllidine is converted into d-sparteine (p. 133). On exhaustive methylation one nitrogen atom is eliminated in three stages, leaving a product, b.p. 235-255°/ll mm., as a viscous, yellow, alkaline oil of uncertain composition. Aphylline, on similar treatment, yields hemiaphylline, CjgH jON, b.p. 217-220°, as a viscous, yellow oil, not markedly basic. 

Strychiyne, strychnidine and tetrahydrostrychnine are all converted into dihydro-derivatives on catalytic hydrogenation, indicating the presence of one ethylenic linkage in these substances, and dihydrostrychnine in turn yields on electrolytic reduction dihydrostrychnidine and hexa-hydrostrychnine. The formation of this group of reduction products from strychnine may be represented thus —... 

EbuUioscopic method, 37 Electrolytic reduction, oxalic acid, 102 nitrobenzene, 144, 145 Eosin, 187 Epichlorhydrin, in Estimation of carbon and hydrogen, 4 halogens, 22 nitrogen, 13 sulphur, 28 Ether, 59... 

Alternatively, hydroxylammonium salts can be made either (a) by the electrolytic reduction of aqueous nitric acid between amalgamated lead electrodes in the presence of H2SO4/HCI, or (b) by the hydrogenation of nitric oxide in acid solutions over a Pl/charcoal catalyst ... 

Dihydrostreptomycin sulfate may be prepared from streptomycin sulfate by catalytic hydrogenation (Merck, Pfizer, Cyanamid), electrolytic reduction (Schenley, Olin Mathieson), or by sodium boro hydride reduction (Bristol), or by isolation from a fermentation process (Takeda). 

Nitromethane is reacted with formaldehyde to give tris(hydroxymethyl)nitromethane in an initial step. This Intermediate may be reduced by catalytic hydrogenation (U.S. Patent 2,174,242) or by electrolytic reduction (U.S. Patent 2,485,982),... 

Reduction, see also Hydrogenation electrolytic, see Electrolysis of anisoin to deoxyanisoin by tin and hydrochloric acid, 40, 16 of aromatic compounds to dihydroaromatics by sodium and ammonia, 43, 23... 

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. " " ... 

On account of the fact that the electrode potential of molybdenum is more negative than the discharge potential of hydrogen, principle difficulties arise to cathodically electrodeposit molybdenum chalcogenide films from aqueous solutions. Theoretically, the deposition of pure molybdenum by electrolytic reduction of molybdates in acidic aqueous solutions is possible according to the reaction... 

Markovic NM, Tidswell IM, Ross PN. 1994. Oxygen and hydrogen peroxide reduction on the gold(lOO) surface in alkaline electrolyte the roles of surface structure and hydroxide adsorption. Langmuir 10 1-4. 

I, 4-benzoquinone.4 Other methods that have been employed include the oxidation of naphthalene with hydrogen peroxide,5 the oxidation of 1,4-naphthalenediamine 6 and naphthylamine sulfonic acid 7 and the oxidation of 4-amino-1-naphthol prepared by electrolytic reduction of 1-nitronaphthalene.8... 

Metallic powders are made several different ways. They can be prepared by reducing salts in a stream of a reducing gas, such as hydrogen chlorides of metals are commonly used but oxides are used too. Thermal decomposition in a vacuum of metal carbonyls or metal salts of organic acids, such as formates, produces metal powders. Surface areas of such powders are around 1.5 m2/g. Powders can also be made from electrolytic reduction of salts in organic solvents and by atomization of the metal. 

Harle and Lyons isolated a mixture of dl and meso hydrodimers from the electrochemical reduction of coumarin (146) at pH 6.8 14t Archer and Grim-shaw, on the other hand, isolated a single diastereomer in high yield upon electrolytic reduction of 3-phenylcoumarin (147) in methanolic hydrogen chloride 141), Interpretation of the difference between the behavior of 146 and 147... 

Dissolving metal reductions were among the first reductions of organic compounds discovered some 130 years ago. Although overshadowed by more universal catalytic hydrogenation and metal hydride reductions, metals are still used for reductions of polar compounds and selective reductions of specific types of bonds and functions. Almost the same results are obtained by electrolytic reduction. 

The most important factor in electrolytic reduction (electroreduction) is the nature of the metal used as a cathode. Metals of low overvoltage - platinum (0.005-0.09 V), palladium, nickel and iron - give generally similar results of reduction as does catalytic hydrogenation [727]. Cathodes made of metals of high overvoltage such as copper (0.23 V), cadmium (0.48 V), lead (0.64 V), zinc (0.70 V) or mercury (0.78 V) produce similar results to those of dissolving metal reductions. 

Diazines (pyrazines) afforded hexahydro derivatives by catalytic hydrogenation over palladium on charcoal at room temperature and 3-4 atm [484, 485] (yield of 2-butylpiperazine was 62% [484], yield of 2,5-diphenylpiperazine 80% [455]). Electrolytic reduction gave unstable 1,2-, 1,4- and 1,6-dihydro-pyrazines [485]. 

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