Vanadium sulfate reductions

The compound can be prepared from 2,4,6-trinitrophenol (picric acid [88-89-1]) by reduction with sodium hydrosulfide (163), with ammonia —hydrogen sulfide followed by acetic acid neutralization of the ammonium salt (164), with ethanolic hydrazine and copper (165), or electrolyticaHy with vanadium sulfate in alcoholic sulfuric acid (159). Heating 4,6-dinitro-2-benzamidophenol in concentrated HQ. at 140°C also yields picramic acid (166). 

Among some kinds of reactions which are slow on a relevant time scale and in particular environments are certain metal-ion oxidations, oxidation of sulfides, sulfate reduction, various metal ion polymerizations (e.g., vanadium, aluminum), aging of hydroxide and oxide precipitates, precipitation of metal-ion silicates and carbonates (e.g., dolomites), conversions among aluminosilicates (e.g., feldspar-kaolinite), and solution or precipitation of quartz (9). Some of these reactions can be accelerated greatly by biological catalysis (e.g., sulfate reduction, metal ion oxidations) (7). 

Fig. 4 shows the TPR profiles of the fresh and spent catalyst. Curve C shows the desorption of hydrocarbons during reduction of the spent catalyst, formed by reduction of carbonaceous deposits on the catalyst surface. The hydrogen consumption profiles of the catalyst (see Curve A and B) show the two peaks, characteristic of palladium sulfate-based catalysts, with a vanadium oxide reduction peak at approximately 400 K and a sulfate reduction peak at 600 K [11,13,16]. The peak position of the sulfate reduction peak is comparable for both catalysts. For the spent catalyst, however, an additional small hydrogen consumption is observed at 700 K, which coincides with the large peak in the FID signal,... 

Uranium by ferrous sulfate reduction in phosphoric acid and dichromate titration method C1267 Test method for uranium by iron (II) reduction in phosphoric acid followed by chromium (VI) titration in the presence of vanadium... 

Vanadium(IV) Oxysulfate. Vanadium(IV) oxysulfate pentahydrate (vanadyl sulfate), VOSO4 -5H20) is an ethereal blue sohd and is readily soluble in water. It forms from the reduction of V20 by SO2 in sulfuric acid solution. Vanadium(III) sulfate [13701 -70-7] ) is a powerful... 

Demet X procedure simply consists of an oxidation at elevated temperature, both the New Demet and the Demet III process has a sulfiding step which transforms the metal oxides to insoluble sulfides. In Demet III the sulfiding step is followed by a partial oxidation step. This oxidation is carefully controlled to produce metal sulfates and sulfides which can be directly removed by washing or be transferred into soluble compounds by the reductive and oxidative washes used in this procedure. In the New Demet process the sulfiding step is followed by chlorination which results in a transformation of the sulfides into washable chlorides. Since vanadium chlorides are volatile, most of the vanadium removal using this procedure occurs in the gas phase. In the Demet X procedure, the vanadium oxides formed are water soluble or can be transformed into water soluble forms by aqueous treatments. In contrast the nickel oxides are insoluble in water. 

Elemental composition V 56.02%, O 43.98%. An acid solution is analyzed for vanadium (See Vanadium). Pentoxide in sulfuric acid may he converted to vanadyl sulfate hy reduction with SO2 (See Reactions) or ferrous ammonium sulfate (FAS). The excess FAS may he destroyed with ammonium persulfate. Vanadyl sulfate is then titrated with a standard solution of potassium permanganate ... 

For vanadium(III) /8-diketonates the recommended preparation is reduction with the dithionite of compounds such as oxovanadium(IV) sulfate, vanadium(V) oxide or ammonium vanadate followed by the addition of the /3-diketone in alcohol.240... 

Vanadium treatment in animals has been shown to interfere with the development of malignant tumors. In 1984, oral treatment with vanadyl sulfate was shown to decrease the induction of mammary carcinoma [167], New experiments have involved treatment to induce a mammary carcinoma in rats started on oral vanadate treatment that continued for 35 weeks. Vanadium treatment protected the rat from development of cancer as determined histologically. In addition, a significant reduction in incidence of total number of tumors and a delay in time to tumor appearance was observed. Vanadium-treated animals had lower tissue distribution of metallothio-nein, a prognostic marker for breast cancer. The mammary tissue in the vanadium-treated group showed increased apoptosis, which could be related to the anticarci-nogenic effect [168],... 

The only simple sulfates of vanadium are formed in the oxidation states -1-3 and -1-2. Vanadium(III) sulfate can be crystallized as a hydrate from aqueous solution, and is strongly reducing. It gives rise to a series of alums of the type M V(S04)2-12H20, which have been shown to contain the [V(H206)] + ion. The ammonium alum, (NH4)V(S04)2 12H20, is obtained as air-stable blue violet crystals by electrolytic reduction of NH4[V03] in sulfuric acid.b ... 

The X-ray microanalytical studies suggest that accumulated vanadium is not found in aqueous intracellular volumes such as vacuoles but occurs mainly in hydrophobic granules and membranes. Chelation by a mixture of ligands including water, sulfate, and tunichrome could have two effects on the lower oxidation states of vanadium, namely, to decrease the reduction potential and increase the stabilization at physiological pH. The EPR line-width studies (145), carried out on whole blood samples and based on aqua vanadyl models, may simply be inappropriate or applicable to only a fraction of the acciunulated vanadium. 

Low valent species of transition metals (Groups IVB, VB and VIB) have found widespread use in the reduction of nitro compounds. Chromium(II) chloride, titanium(III) chloride and vanadium(II) sulfate readily reduce aromatic nitro compounds to arylamines. Chromium(II) chloride also reduces nitrobenzene and nitroquinoline to the corresponding amines in excellent yields. ... 

Vanadia doped sulfated Ti-pillared clay are highly active for the reduction of NO by ammonia in the presence of oxygen. The results of SCR reaction show that vanadium present mainly astthe +5 valence played an important role in this reaction. SCR activity was found to be correlated to acidity at high temperature. At low temperatures, the redox properties play a key role for the activity. 

Pure anhydrous vanadium(III) sulfate can be prepared by the reduction of vanadium(V) oxide dissolved in sulfuric acid with elemental sulfur as the reducing agent.The procedure given below is an adaptation of this method. 

Vanadium(II) sulfate can be prepared by reduction of vanadium (V) oxide in sulfuric acid solution either electro-lytically or with sodium amalgam or with zinc, followed by evaporation of the solution in vacuo over phosphorus (V) oxide.It also may be prepared by the electrolytic reduction of vanadium(IV) oxide sulfate, VOSO4, which is the basis of this procedure. 

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