Ferrous chloride, oxidation preparation

Iron oxide yellows can also be produced by the direct hydrolysis of various ferric solutions with alkahes such as NaOH, Ca(OH)2, and NH. To make this process economical, ferric solutions are prepared by the oxidation of ferrous salts, eg, ferrous chloride and sulfate, that are available as waste from metallurgical operations. The produced precipitate is washed, separated by sedimentation, and dried at about 120°C. Pigments prepared by this method have lower coverage, and because of their high surface area have a high oil absorption. 

Numerous methods for the synthesis of salicyl alcohol exist. These involve the reduction of salicylaldehyde or of salicylic acid and its derivatives. The alcohol can be prepared in almost theoretical yield by the reduction of salicylaldehyde with sodium amalgam, sodium borohydride, or lithium aluminum hydride by catalytic hydrogenation over platinum black or Raney nickel or by hydrogenation over platinum and ferrous chloride in alcohol. The electrolytic reduction of salicylaldehyde in sodium bicarbonate solution at a mercury cathode with carbon dioxide passed into the mixture also yields saligenin. It is formed by the electrolytic reduction at lead electrodes of salicylic acids in aqueous alcoholic solution or sodium salicylate in the presence of boric acid and sodium sulfate. Salicylamide in aqueous alcohol solution acidified with acetic acid is reduced to salicyl alcohol by sodium amalgam in 63% yield. Salicyl alcohol forms along with -hydroxybenzyl alcohol by the action of formaldehyde on phenol in the presence of sodium hydroxide or calcium oxide. High yields of salicyl alcohol from phenol and formaldehyde in the presence of a molar equivalent of ether additives have been reported (60). Phenyl metaborate prepared from phenol and boric acid yields salicyl alcohol after treatment with formaldehyde and hydrolysis (61). 

Aqueous solutions of ferric chloride are conveniently prepared by dissolving iron in hydrochloric acid and subsequently saturating the solution with chlorine to oxidise the ferrous salt to the ferric condition. After standing, the solution should still smell of chlorine, otherwise sufficient of the gas has not been added. Excess may now be removed by bubbling carbon dioxide through the warm solution. Other methods of preparation consist in dissolving ferric hydroxide in aqueous hydrochloric acid and by oxidation of ferrous chloride in the presence of hydrochloric acid by some oxidiser such as nitric acid. 

Pure iron is prepared by reduction of ferrous chlorid, or of ferric oxid, by H at a temperature approaching redness. 

Superparamagnetic iron oxide particles stabilized with alginate have been successfully prepared by Ma et al. (2007). Ferric and ferrous chlorides (molar ratio... 

The antioxidant activity of phenols used and standards was determined according to die ferric thiocyanate method with minor modifications. Each sample of treated wool (200 mg) was mixed with 2 mL distiUed water and 5 mL linoleic acid emulsion (0.02 M, pH 7.0) and 5 mL phosphate bufier (0.2 M, pH 7.0). Linoleic acid emulsion was prepared by mixing 0.5608 g of linoleic acid with 0.5608 g of Tween 20 as emulsifier, and 100 mL phosphate buffer (0.2 M, pH 7.0), and then the mixture was homogenised. The reaction mixture was incubated at 37 C. Aliquots of 0.1 mL wm taken at different intervals during incubation. The degree of oxidation was measured by sequentiaUy adding 4.7 mL ethanol (75%), 0.1 mL ammonium diiocyanate (30 %), 0.1 mL sample solution and 0.1 mL ferrous chloride (0.02 mg, in 3.5% HCl). The mixture was... 

As an example, the commercial preparation of aniline may be described. Nitrobenzene is reduced by finely divided iron and water with a little hydrochloric acid, the products formed being ferrous chloride, magnetic oxide of iron and aniline. The aniline is distilled over with steam and the greater part of it separates from the distillate on standing. The aqueous layer, which contains a little aniline, is afterwards placed in the boiler which supplies steam to the still, so that in the next distillation the aniline is carried over into the still again. 

The original preparation of this pigment was by Monthiers (hence the synonymous Monthier s blue, q.v.) where ordinary Prussian blue (q.v.) was treated with ammonia. Gardner et al. (1978) describe the preparation as by oxidation of the precipitate formed through the action of atnmoniacal ferrous chloride on potassium ferrocyanide. Riffault et al. (1874) also describe the... 

Reaction of ferrous chloride with cyanide ions in the presence of CO produces a mixture of cyano-carbonyl ions including T[Fe(CN)4(CO)2], /ra 3-[Fe(CN)4(CO)2] , and [Fe(CN)s(CO)] (Scheme H).63.70,7l OT-dicarbonyl compound was also prepared via the reaction of Fe(CO)4l2 with 4 equiv. of MCN (M = Na, K) in MeOH (Scheme Z) Treating [Fe(CN)3(CO)3] with NaCN also produced the m-derivative. As with the previous work reviewed in GOMC II (1982) and COMC (1995), alkylation of these anionic cyano complexes leads to isocyanide derivatives. Similarly, protonation leads to the formation of the bound isocyanic acid. Oxidation of the [Fe(CN)s(CO)] ion gives [Fe(CN)s(CO)]. Two-dimensional polymeric networks were obtained when [Na(DMF)2]2[7ra .f-Fe(GN)4(CO)2] was treated with divalent metal salts in agar gels (Equation (22)). ... 

The chemical change in the Fricke dosimeter is the oxidation of ferrous ions in acidic aerated solutions. It is prepared from a -1 mM solution of ferrous or fer-roammonium sulfate with 1 mM NaCl in air-saturated 0.4 M H2S04. Addition of the chloride inhibits the oxidation of ferrous ions by organic impurities, so that elaborate reagent purification is not necessary. Nevertheless, the use of redistilled water is recommended for each extensive use. Absorption due to the ferric ion is monitored at its peak -304-305 nm. The dose in the solution is calculated from the formula... 

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