Vanadyl arsenates

Vanadyl Arsenates.—Two of these have been prepared by the action of hydrated hypovanadic oxide on solutions of arsenic acid 2V02.2As206.3H20 and 2V02.3As205.6H20. They are both sky-blue, crystalline compounds, and the latter rapidly becomes green on exposure to air.1... 

Figure 6.10 Structure of VOPO4.2H2O. (Reprinted with permission from Inorganic Chemistry, Coordination intercalation reactions of the layered compounds vanadyl phosphate (VOPO4) and vanadyl arsenate (VOASO4) with pyridine by J. W. Johnson, A. J. Jacobson, J. F. Brody and S. M. Rich, 21, 10. Copyright (1982) American Chemical Society)...

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. 

Solutions of arsenic acid are reduced to arsenious acid by sulphur dioxide, slowly in the cold but more rapidly when heated.8 The rate of reduction depends upon the degree of acidity of the solution 9 and is complete only after prolonged heating or boiling unless the operation is carried out in a closed vessel.10 Under the latter conditions the reaction may be used for the preparation of arsenious oxide.11 The reduction is greatly retarded by the presence of vanadie acid in dilute sulphuric acid solution,12 but proceeds rapidly if the mixture is heated with a trace of potassium iodide present. Complete reduction of the mixture to arsenious acid and a vanadyl salt may then be brought about by heating in a sealed vessel for about one hour on a water-bath.13... 

Ramis et al. [44] studied the effect of dopants and additives on the state of surface vanadyl species of vanadia on titania catalysts by means of FTIR spectroscopy. Additives such as alkali and alkali-earth metal cations (typically Cs, K, Na, Li and Mg), oxoanions (such as sulphates and arsenates), and other species (such as AP+, MoO +, and WO ), influence the position of V=0 stretching frequencies. The position of vy=o for a 3 wt% V2O5 on titania was observed at 1035 Two percent W or Mo did not show any shift of the stretching frequency of V=0, whereas Cs lowered the band position by 45 cm . This was explained in terms of the formation of strong basic sites and the exchange of Ti in 0=V-0-Ti by 0=V-0-Cs. The elements Al, S, and As shift the position of vv=o to higher frequencies. Oxoanions are coordinatively bond to vanadyl centers [44],... 

AI3-52349 Dichlorooxovanadium EINECS 233-617-7 NSC 79625 Vanadium chloride oxide Vanadium dichloride oxide Vanadium, dichlorooxo- Vanadium oxychloride Vanadyl chloride Vanadyl dichlorlde. Strong reducing agent, used in purification of hydrogen chloride from arsenic and as a mordant in printing fabrics. Green crystals d = 2.88 disproportionates at 384° soluble in EtOH, AcOH, decomposes with H2O. Atomergic Chemetals Noah Chem. 

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