Cobalt arsenites

Cobalt Arsenites.—Several compounds have been prepared. Cobalt ortho arsenite, Co3(As03)2.4H20, is obtained3 as a pink precipitate when a solution of cobaltous chloride in 50 per cent, alcohol is treated with a solution of potassium orthoarsenite which has been just neutralised with acetic acid. The precipitate is soluble in dilute acids. On heating it turns black. A basic salt, of composition 7Co0.As203, is obtained when a solution of cobalt nitrate is treated with sodium orthoarsenite,6 the former being in excess the amethyst-coloured precipitate first formed contains combined water, which may be completely removed at 150° C. 

Cobalt Arsenites.—When a dilute solution of cobalt nitrate is precipitated with sodium metarsenite, a violet-blue voluminous deposit of cobalt pyro-arsenite, Co2As205 or 2CoO.As203, is obtained.3... 

Arsenic species. Soluble arsenites and arsenates precipitate Co forming the corresponding cobalt arsenite or arsenate, bluish white, soluble in NH3 or in adds, including arsenic acid. 

Kharab P, Singh I. 1985. Genotoxic effects of potassium dichromate, sodium arsenite, cobalt chloride and lead nitrate in diploid yeast. MutRes 155 117-120. 

Methylation of arsenic is an important pollution problem because of the widespread use of arsenic compounds in insecticides and because of the presence of arsenate in the phosphate used in household detergents.421 422 After reduction to arsenite, methylation occurs in two steps (Eq. 16-45). Additional reduction steps result in the formation of dimethylarsine, one of the principal products of action of methanogenic bacteria on arsenate. The methyl transfer is shown as occurring through CH3+, with an accompanying loss of a proton from the substrate. However, a CH3 radical may be transferred with formation of a cobalt(II) corrinoid.423... 

A further example of an induced reaction consists in the atmospheric oxidation of an ammoniacal solution of arsenite, which is brought about by the addition of cobaltous sulphate, the latter also being oxidised.1... 

Cobalt Tetrarsenite, Co3As409, is obtained as an amethyst-coloured powder by the interaction of solutions of potassium hydrogen di-arsenite and cobaltous nitrate.8 It dissolves in dilute hydrochloric and nitric acids also in caustic potash, in which it forms a blue solution which decomposes on heating. In aqueous ammonia it gives a brown solution, and in aqueous potassium cyanide a yellow one. 

Tri-cobalt Di-arsenide, Co3As2, may be prepared by the action of arsenic chloride on metallic cobalt at 800-1400° C. or by heating mixtures of arsenic and cobalt in hydrogen or carbon monoxide at this temperature. It is also formed when powdered cobalt is heated in hydrogen containing arsenic vapour, and when cobalt arsenate or arsenite is reduced by hydrogen at 900° C. Its density is 7-82, and it loses arsenic when strongly heated.1... 

The carbonates, sulphates, and borates are decomposed. The sulphides of the alkalies and alkaline earths are decomposed while the sulphides of arsenic, antimony, molybdenum, zinc, cadmium, tin, iron, lead, copper, mercury, and palladium are not attacked. Cobalt sulphate is not attacked, while the sulphates of the alkalies and alkaline earths are attacked and dissolved. Alkali tungstates, ammonium arsenite and arsenate, copper arsenite, ammonium magnesium arsenate, ammonium molybdate and vanadate, potassium cyanide and ferrocyanide are decomposed. Paraffin is not attacked shellac, gum arabic, gum tragacanth, copal, etc., are decomposed. Celluloid is slowly attacked. Silk paper, gun cotton, gelatin, parchment are dissolved. M. Meslans 22 has studied the esterification of alcohol by hydrofluoric acid. 

Since 1910 the method of Bart has been modified by a number of investigators, Bart, himself, being the first to improve the reaction. He found that coupling of aryldiazonium compounds with alkali arsenites is catalyzed by copper salts and by silver or copper powder. In a later patent the use of metallic catalysts, copper, nickel, or cobalt, as well as their salts is said to facilitate the removal of diazo nitrogen at low temperatures and to obviate the formation of by-products. Though many have since observed that the coupling reaction is speeded by the use of the above catalysts, no systematic study has been made to determine the effect of such catalysts on the final yield. 

Ions that can be analyzed by electrochemical detection include cyanide, sulfide, hypochlorite, ascorbate, hydrazine, arsenite, phenols, aromatic amines, bromide, iodide, and thiosulfate [53], nitrite and nitrate [54.55], cobalt and iron [46], and others. The list may be extended through the technique of post-column derivatization to include many more ions such as carboxylic acids, halide ions, alkaline earth ions, and some transition metal ions [57,58). An example of an electrochemical reaction to detect ions is shown by Eq. 4.8. 

The growth of the bacterium is inhibited by benzoic acid, sorbate, and sodium laurylate (Onysko et al., 1984), and nitrate at 50 mM inhibits completely the oxidation of ferrous ion by the bacterium (Eccleston et al., 1985). Although the bacterium is sensitive to chloride ion, it becomes resistant to 140 pM chloride ion by training (Shiratori and Sonta, 1993). The bacterium is fairly resistant to heavy metal ions its activity to oxidize ferrous ion is scarcely inhibited in the presence of 65 mM cupric ion, 100 mM nickel ion, 100 mM cobalt ion, 100 mM zinc ion, 100 mM cadmium ion, and 0.1 mM silver ion (Eccleston et al., 1985). The bacterium acquires the ability to grow even in the presence of 2 mM uranyl ion (Martin et al., 1983). Furthermore, it becomes resistant to arsenate and arse-nite by training a strain of the bacterium has been obtained which oxidizes ferrous ion in the presence of 80 mM arsenite and 287 mM arsenate (Collinet and Morin, 1990 Leduc and Ferroni, 1994). The resistant ability of the bacterium to arsenite and arsenate is important when they are applied for the solubilization of arsenopyrite (FeAsS) [reactions (5.8) and (5.9)]. Leptospirillum ferrooxidans is generally more sensitive to heavy metal ions than A. ferrooxidans (Eccleston et al., 1985). 

Hypochlorite, ascorbate, hydrazine, arsenite, thiosulfate, nitrite, nitrate, cobalt and iron are a partial list of the ions that have been detected using amperometric detection [55]. The most common ions determined by amperometric detection in 1C include inorganic anions forming complexes with cyanide, sulfide, and iodide at a silver electrode [56]. The relevant chemical reaction is shovra below. 

Cobalt Niuate Cobalt Nitrate Cobalt Sulfate Cobalt Sulfate Oils Edible Coconut Oils Edible Coconut Oil Resin Oil Rozin Collodion Ethyl Alcohol Methyl Alcohol Methyl Alcohol Methylcyclopentadienyl-manganese Tricarbonyl Polyphosphoric Acid Copper Acetate Copper Acetoarsenite Copper Arsenite Ferrous Sulfate Copper Pluoroborate Copper Bromide Copper Chloride Copper Cyanide Copper Pluoroborate... 

Fiedler and Bayard (1997) associate Swedish green with Scheele s green (copper arsenite). The Swedish chemist Carl Wilhelm Scheele both discovered and produced the green pigment which bears his name and as ftie pigment was first manufactured in Sweden the colour was also associated with that coimtry. Mayer (1991) on the other hand links Swedish green to the term cobalt green (q.v). 

Au-UMEA gold ultramicroelectrode array Au NPs gold nanoparticles PBS phosphate buffer solution IrO iridium oxide BDD boron doped diamond PBSPE Prussian blue-modified screen-printed electrode MWCNTs multi-walled carbon nanotubes Aro arsenite oxidase CoO cobalt oxide. 

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