Cobalt ferricyanide

Cobalt ferricyanide, Co3[Fe(CN)6]2 is a red precipitate resulting when potassium ferricyanide and cobalt sulphate solutions are mixed. The ammoniates Co3[Fe(CN)6]2.4NH3.6H20 11 and Co3[Fe(CN)6]2.8NH3 12 have been prepared. 

Hydrogen Peroxide Analysis. Luminol has been used for hydrogen peroxide analysis at concentrations as low as 10 M using the cobalt(III) triethanolamine complex (280) or ferricyanide (281) as promoter. With the latter, chemiluminescence is linear with peroxide concentration from... 

Chemical complexes of various transition metals have been shown to promote N-nitrosation (28). These metal complexes include ferrocyanide, ferricyanide, cupric ion, molybate ion, cobalt species, and mercuric acetate. All of the reactions are thought to proceed by oxidation-reduction mechanisms. However, such promotion may not be characteristic of transition metal complexes in general, since ferricyanide ion has been shown to promote nitrosation in metalworking fluids, whereas ferric EDTA does not (2 0). Since the metalworking operation generates metal chips and fines which build up in the fluids, this reaction could be of significance in the promotion of nitrosamine formation in water-based metalworking fluids. 

Potassium cobalt(II) ferricyanide [potassium cobalt(II) hexakis(cyano-ferrate(3-))] KCoii[Fe(CN)6] [14874-73-8]... 

The double compound, [Cr(NH3)6H20][Cr(CN)8], is precipitated from the aquo-pentammino-chloride on addition of potassium chromi-cyanide it separates as a sparingly soluble yellow crystalline powder, and on heating with concentrated hydrochloric acid decomposes with formation of ehloro-pentammino-chloride. The ferricyanide, [Cr(NH3)B H20][Fe(CN)6], is precipitated from a dilute solution of the aquo-pentammino-ehloride on addition of potassium ferricyanide, and crystallises in vellowish-brown prisms. The cobalti-cyanide, [Cr(NH3)5H20] [Co(CN)6], obtained, by the addition of potassium cobalti-cyanide, in yellowish-brown crystals, is isomeric with the chromi-eyanide of aquo-pentammino-cobalt, [Co(NH3)sH20][Cr(CN)6]. 

However, when small increments of substrate were added to CoH containing added alkali (KOH, 3X cobalt concentration), 1.4 atoms of hydrogen were absorbed per mole of quinone. This effect of alkali is similar to that noted in the reduction of ferricyanide. However, with benzoquinone, the addition of excess substrate to CoH containing added alkali still resulted in the absorption of hydrogen, the hydrogen atom to substrate ratio being reduced to 0.98. Furthermore, the presence of excess quinone during the formation of cyanocobaltate(II) with added alkali did not prevent catalytic reduction. 

Ferricyanide - [CHELATING AGENTS] (Vol 5) - [COBALT COMPOUNDS] (Vol 6) - [COLOR PHOTOGRAPHY] (Vol 6) -with osmium tetroxide catalyst [PLATINUM-GROUP METALS, COMPOUNDS] (Vol 19)... 

Reductive decarboxylation of (20) yields C02, H+, and a Co(I) species at a measurable rate (94). In the presence of CO, the starting cobalt complex is regenerated, and a catalytic system for the oxidation of CO by ferricyanide is established. It is significant that in this system the metal-carbonyl bond is formed when the cobalt is in a reduced state. It is the subsequent oxidation of the cobalt by electron transfer that activated the carbonyl to attack by water or hydroxide. That this activation results in a weaker metal-carbonyl bond is evident since the Co(III)-carbonyl may be hydrolyzed in acidic solution with loss of the carbon monoxide ligand (94). 

Oxidants that operate according to this one-electron oxidation mechanism include potassium ferricyanide in alkaline solution, cobalt, copper complexes with dioxygen, and some enzymes. 

Cobalt ferrocyanide, Co2Fe(CN)6.7H20,9 is obtained by neutralising the free acid with cobalt hydroxide. It is less stable than the corresponding nickel salt. It is green in colour oxidised by chlorine water to ferricyanide and by bromine water to hydrated cobaltic oxide.10... 

More intensive dehydrogenation of primary amines having two hydrogen atoms on the adjacent carbons leads to nitriles. Such dehydrogenations are accomplished by argentic oxide cobalt peroxide [1136], nickel peroxide [936], lead tetraacetate [443, 444], sodium hypochlorite [692], potassium ferricyanide [924], and potassium ruthenate [196] (equation 513). 

Saturated aqueous potassium ferricyanide solution + 6 N hydrochloric acid Aqueous ammonium cobalt rhodanide solution + 6 N hydrochloric acid Yellow precipitate Blue precipitate... 

In the separation of caesium, the following inorganic cation exchangers are particularly useful potassium cobalt(II) hexacyanoferrate(II) [12,13], potassium copper(II) and nickel(II) hexacyanoferrates(II) [14], ammonium molybdophosphate [13,15], zirconium molybdoarsenate [16], thallium tungstophosphate [17], and tin molybdosilicate [18]. Rubidium has been selectively isolated on columns filled with titanium tungstoarsenate [19] or titanium ferricyanide [20]. Ammonium molybdoarsenate has been used to separate potassium from sodium [21]. 

Kihnc, E., A. Erdem, L. Gokgunnec, T. Dalbasti, M. Karaoglan, and M. Ozsoz (1998). Buttermilk based cobalt phthalocyanine dispersed ferricyanide mediated am-perometric biosensor for the determination of xanthine. Electroanalysis 10(4), 273-275. 

The manganese-benzidine reaction, as just described, cannot be used in the presence of other oxidizing agents or autoxidizable substances which likewise oxidize benzidine (chromates, ferricyanides, cobalt, thalliumi, silver, cerium i salts). In such cases, special procedures must be used. 

In order to decrease the overpotential for cysteine oxidation in cysteine-containing peptides, graphite-epoxy resin or carbon paste electrodes with immobilized cobalt phthalocyanine have been employed in HPLC systems [53,87-89]. Glassy carbon electrodes modified with a mixed-valence ruthenium(I V,III) oxide film stabilized by cyano cross-links [61,62], indium ferricyanide [63], or a Prussian blue film [64], and a bismuth(V)-doped lead dioxide Pb02 film on gold [65] have also been used for detection following HPLC separation. In addition, a carbon fiber modified with a nfixed-valence ruthenium(IV,III) oxide film stabilized by cyano cross-links has been used in CE [46]. 

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