Vanadyl acetate

Redox titrants (mainly in acetic acid) are bromine, iodine monochloride, chlorine dioxide, iodine (for Karl Fischer reagent based on a methanolic solution of iodine and S02 with pyridine, and the alternatives, methyl-Cellosolve instead of methanol, or sodium acetate instead of pyridine (see pp. 204-205), and other oxidants, mostly compounds of metals of high valency such as potassium permanganate, chromic acid, lead(IV) or mercury(II) acetate or cerium(IV) salts reductants include sodium dithionate, pyrocatechol and oxalic acid, and compounds of metals at low valency such as iron(II) perchlorate, tin(II) chloride, vanadyl acetate, arsenic(IV) or titanium(III) chloride and chromium(II) chloride. 

Subnormal magnetic oxovanadium(IV) complexes that include this type of ligand have been reviewed by Syamal (Table 24).358 v(V=0) values appear —100 cm-1 lower than commonly found. Vanadyl acetate and halogenoacetates VO(CH3- X C02)2, (n = 1, 2, 3 X = Cl or Br) are characterized by one v(V==0) at 895 5 cm-1, by very low fi(Table 24) and by antiferromagnetic spin-spin interactions. These results have been interpreted on the basis of a polymeric structure (52).358,598 The same characteristics and interactions exist in many complexes of other aliphatic and aromatic carboxylic acids.358 [VO(salnpn)],599 polymeric with... 

Oxovanadium(IV) complexes with (97) and (98) derived from alkyl aminoalcohols and Hsal or o-hydroxyacetophenone (and substituted derivatives), respectively, have been prepared as well as VOz+ complexes with (99) derived from 2-hydrazinoethanol and Hsal and substituted Hsal. Most of these and some properties are summarized in Table 42. Generally the complexes were prepared by adding an alcoholic solution of the SB, either previously obtained as a solid or prepared in situ, to alcoholic vanadyl acetate. The mixture is normally refluxed for several hours and the precipitates are collected by filtration as they are not soluble they are not recrystallized. 

The tetramethyltetraaza[14]annulene (165) reacts with vanadyl acetate to yield (166) similar to complexes of (163) and (164).660 It was the starting material for several reactions shown in Scheme 22, and exhibits a reversible one-electron oxidation wave at +0.245 V (vs. SCE) but reacts irreversibly with mild oxidants (02, Ag+, Ce4+ or I2) to yield (167). With Et3N, (167) yielded a complex with properties similar to (166) but which mass spectral data indicate is a dimer. Structure (170) was proposed. 

Among other organic compounds of vanadium the following are known Vanadous acetate,8 vanadous acetylacetonate, vanadous benzoyl-acetonatef vanadous carbamides,10 vanadyl acetonates,11 vanadyl acetate,... 

Polystyrene-supported vanadyl acetate catalyses the oxidation of a range of substrates, including dimethyl sulfide to the sulfone, di-n-butylthioether to the sulfoxide, and cyclohexene to the epoxide.73 A series of trinuclear carboxylate complexes [M30(02CR)6(H20)3]n+ (M = V, Cr, Mo, Mn, Ru, Co or Rh)... 

Complete the solution of the crystal structure and perform Rietveld refinement of the model of vanadyl acetate, VO(CH3COO)2, using the model established in problem 9, Chapter 6. The experimental powder diffraction pattern is located on the CD in the file Ch7Pr05 CuKa.raw. 

The cobalt complex is usually formed in a hot acetate-acetic acid medium. After the formation of the cobalt colour, hydrochloric acid or nitric acid is added to decompose the complexes of most of the other heavy metals present. Iron, copper, cerium(IV), chromium(III and VI), nickel, vanadyl vanadium, and copper interfere when present in appreciable quantities. Excess of the reagent minimises the interference of iron(II) iron(III) can be removed by diethyl ether extraction from a hydrochloric acid solution. Most of the interferences can be eliminated by treatment with potassium bromate, followed by the addition of an alkali fluoride. Cobalt may also be isolated by dithizone extraction from a basic medium after copper has been removed (if necessary) from acidic solution. An alumina column may also be used to adsorb the cobalt nitroso-R-chelate anion in the presence of perchloric acid, the other elements are eluted with warm 1M nitric acid, and finally the cobalt complex with 1M sulphuric acid, and the absorbance measured at 500 nm. 

Urea Peroxide Urea Peroxide Hexamethylenetetramine Hexamethylenetetramine Antimony Trioxide Valeraldehyde Valeraldehyde Valeraldehyde Vinyl Acetate Vanadium Pentoxide Vanadyl Sulfate Vanadium Oxytrichloride Vanadium Pentoxide Vanadium Pentoxide Vanadium Oxytrichloride Vanadyl Sulfate Vanadyl Sulfate Vanadium Oxytrichloride Captan... 

Phenoxazine (28 mg, 0.25 mmol), iodylbenzene (118 mg, 0.25 mmol) and vanadyl acetylacetonide (13 mg, 0.05 mmol) were refluxed in benzene for 4 h. After concentration, the residue was chromatographed (silica gel, hexane-ethyl acetate, 8 2) to give the title compound (22 mg, 72%), m.p. 214°C. 

A method for the preparation of vanadyl (IV) acetate in non-aqueous media, as reported earlier,1 involves solvolysis of vanadyl(V) chloride in acetic anhydride. However, a quicker... 

Vanadyl pyrophosphate is widely considered to play an important catalytic role in the oxidation of -butane to MA, specifically the (100) face (Figure 18b), which is retained from the topotactic transformation (6,43,84—86) of the catalyst precursor phase (Figure 18a). Furthermore, this active phase has been reported to be an efficient catalyst for the oxyfimctionalization of light paraffins (a) for the oxidation of ethane to acetic acid (3,87), (b) for the oxidation and ammoxidation of propane to acrylic acid (88) and acrylonitrile (89,90), respectively, and (c) for the oxidation of n-pentane to maleic and phthalic anhydrides (90-102). 

Tripodal N2O2 and N3O iminocarboxylate ligands such as (102) and (103) have appeared, with the vanadyl complexes acting as halogenperoxidase models. Binuclear Mn and Mn complexes feature linked MnL units. Related N3O and N2O2 aminoalcohol ligands are known, exemplified by (104), which forms a mononuclear trigonal bipyramidal complex with Cu with acetate or thiocyanate as the additional donor, and (105), which forms a square-pyramidal Fe complex that exhibits catalytic activity as a model for catechol-1,2-dioxidase. 

Sol in acet, tetrahydrofuran and eth acetate, si sol in n-heptane and methanol v si sol in toluene and w. Prepn of the initial polymer is from a dioxane soln at 50° of 2.0 equiv mol wts each of the monomers using either 1.5 equiv wt % of boron trifluoride etherate or 2.0 equiv wt % of vanadyl acetylacetonate as a catalyst to enhance the polymerization rate. Complete polymerization or gel is accomplished in about 70 hrs at 50°. The reaction rate is further enhanced by the addition of 0.072 equiv wt % of the isocyanate monomer after the initial reaction, resulting in gelation after 40 hrs at 50°. The hot dioxane soluble product is w pptd, vacuum steam-distd and dried. Post polymerization nitration of the polymer is accomplished with 100% nitric acid at 65°... 

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