Vanadous acetate molybdates

The derivatization of aldehydes in reducing carbohydrates can also be performed by a condensation reaction between the active hydrogens of l-phenyl-3-methyl-5-pyrazolone (PMP) and the aldehyde functionality under slightly basic condition. The formed bis-PMP derivatives can be separated by CZE and detected by UV absorbance. Oligosaccharides can also be separated as complexes with a variety of compounds, including acetate, molybdate, germanate, stannate, arsenite, wolfra-mate, vanadate, and tellurate of various alkali and alkaline... 

Excess fluoride ions prevent the reaction through the formation of stable [TiFe] ions. However, by demasking, it is possible to detect titanium in the presence of even large amounts of fluoride (see below). Large eimounts of acetates, nitrates, chlorides, bromides, and colored ions reduce the sensitivity. Chromates, vanadates, and molybdates, should not be present because they too give color reactions with hydrogen peroxide. Iron salts yield... 

H. 8-Hydroxyquinaldine (XI). The reactions of 8-hydroxyquinaldine are, in general, similar to 8-hydroxyquinoline described under (C) above, but unlike the latter it does not produce an insoluble complex with aluminium. In acetic acid-acetate solution precipitates are formed with bismuth, cadmium, copper, iron(II) and iron(III), chromium, manganese, nickel, silver, zinc, titanium (Ti02 + ), molybdate, tungstate, and vanadate. The same ions are precipitated in ammoniacal solution with the exception of molybdate, tungstate, and vanadate, but with the addition of lead, calcium, strontium, and magnesium aluminium is not precipitated, but tartrate must be added to prevent the separation of aluminium hydroxide. 

The frequent occurrence of vanadium in uranium minerals renders the separation of these two metals of importance. One method in use is based on the solubility of uranyl nitrate in ether, %vhilst vanadic and also molybdic and tungstic acids are insoluble. A solution containing these substances may therefore be evaporated to drjmess, and the uranyl salt extracted from the residue with ether. Another method depends upon the fact that uranyl nitrate is readily soluble, whilst vanadium compounds are insoluble, in acetic acid of 95 per cent, strength to which nitric acid has been added in the proportion 1 20. ... 

One of the simplest methods of preparation is by decomposition of a thermally unstable compound. The nitrate or chloride is often preferred, sulphates tend to decompose at higher temperatures. Where the presence of residual traces of anion is to be avoided, the metal salts of organic acids are particularly useful. Formates, oxalates, acetates etc, decompose at low temperatures and often reduce the metal at the same time. For the preparation of catalysts from anions, the ammonium salt is frequently used. Metallic salts of complex acids can be used as a source of metal oxide mixtures. Decomposition of the appropriate chromate, tungstate, molybdate or vanadate will produce the mixed oxide. 

Mixtures of acetaldehyde and acetic acid may be obtained121 by passing acetylene (2 to 3 volumes) and air (10 volumes) mixed with a large excess of steam over the zinc, copper, nickel, or cadmium salts of vanadic, molybdic, or chromic acids deposited upon a suitable base, such as pumice, at temperatures ranging from 300° to 400° C. For example, yields of 75 to 80 per cent acetaldehyde along with 5 per cent acetic acid have been obtained by using basic zinc vanadate at 380° C. The aldehyde is separated by fractional condensation in a column and the condensed fraction which is poor in aldehyde is utilized to furnish steam for the catalytic treatment of more acetylene. The fractions rich in acetaldehyde serve for the direct recovery of the aldehyde or may be oxidized immediately to acetic acid by passage over a suitable catalyst. In this way, the process may also be applied directly to the preparation of acetic acid from acetylene. 

Hydroxyquinoline (oxine) reacts with numerous metal ions, in neutral, ammoniacal, or acetic acid solution, to produce inner complex salts of the coordination structure (II). Anions of metallo acids (molybdic, tungstic, vanadic) react in acetic acid solution to form insoluble compounds of a different structure probably the oxine esters of the particular metallo acid are formed. The vanadium compound is represented by (III). ... 

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