Cobalt vanadates

Others manganese blue cobalt, manganese violet naples yellow, bismuth vanadate ... 

Cobalt Metavanadate, Co(V03)2.Sli20, separates out on boiling a solution of ammonium vanadate with excess of cobalt nitrate which has been feebly acidified with nitric add.9 It is easily soluble in water. 

Cr(II) may be used to carry out all the reactions of Ti(III), but usually under milder conditions. Applications of Cr(II) as a reductant have been reviewed. The applications include Sn(IV) chloride in the presence of catalysts such as Sb(V) or Bi(III), Sb(V) in 20% HCl at elevated temperatures, Cu(II), silver, gold, mercury, bismuth, iron, cobalt, molybdenum, tungsten, uranium, dichromate, vanadate, titanium, thallium, hydrogen peroxide, oxygen in water and gases, as well as organic compounds such as azo, nitro, and nitroso compounds and quinones. Excess Cr(II) in sulfuric acid solution reduces nitrate to ammonium ion. The reduction is catalyzed by Ti(IV), which is rapidly reduced to Ti(III). 

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. 

Among the other notations is that acetaldehyde is to be avoided, it being a respiration inhibitor. It is related to ethyl alcohol or ethanol and also to acetic acid, but not necessarily to citric acid as involved in the carboxylic acid or citric acid cycle. Alkaloids are expectedly respiration inhibitors, and anesthetics can have respiration inhibition as a side effect. Aromatic adds such as phenol are bad news, as are arsenate, cyanide, isothiocyanate, and thiocyanate. The heavy metals cadmium, cobalt, copper, ruthenium, vanadate, and zinc are regarded as health risks, if not for respiration, for other reasons. 

Fig. 15. Activities of first-row transition-metal oxide perovskites for CO oxidation in a 2 1 mixture of CO and 02 at atmospheric pressure (a) or in a 1 1 mixture of CO and 02 at 227°C at atmospheric pressure (b). The activities of vanadates ( ), chromates ( ), manga-nates (A), ferrates (O), cobaltates ( ), and nickelates ( ) are plotted at the appropriate d-orbital occupation corresponding to the average valence of the transition-metal ion. (Redrawn by permission from Refs. 14 and 176.)...

Earlier structural studies of carbohydrates by CD involved introduction of suitable chromophores into the sugar molecule thereby affording derivatives which exibit Cotton effects. These include, among others, xanthates (4-8) or azides (9). Later it was found that some metal ions (10), i.e. copper (11,13), vanadate (14), chromium (15), molybdate (16-22), nickel (23) or cobalt (24,25) ions form complexes with carbohydrates, which show appreciable Cotton effects. 

A new homogeneous WOC, based on a redox-active vanadate(v)-centred polyoxometalate, has been prepared from a mixture of cobalt ions, vanadate (NaV03), and tungstate (Na2W04) in aqueous solution. The obtained compound, Naio[Co4(H20)2(VWg034)2] 35H2O, is able to catalyse... 

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