Vanadium complexes arsenates

Early catalysts for acrolein synthesis were based on cuprous oxide and other heavy metal oxides deposited on inert siHca or alumina supports (39). Later, catalysts more selective for the oxidation of propylene to acrolein and acrolein to acryHc acid were prepared from bismuth, cobalt, kon, nickel, tin salts, and molybdic, molybdic phosphoric, and molybdic siHcic acids. Preferred second-stage catalysts generally are complex oxides containing molybdenum and vanadium. Other components, such as tungsten, copper, tellurium, and arsenic oxides, have been incorporated to increase low temperature activity and productivity (39,45,46). 

Although trialkyl- and triarylbismuthines are much weaker donors than the corresponding phosphoms, arsenic, and antimony compounds, they have nevertheless been employed to a considerable extent as ligands in transition metal complexes. The metals coordinated to the bismuth in these complexes include chromium (72—77), cobalt (78,79), iridium (80), iron (77,81,82), manganese (83,84), molybdenum (72,75—77,85—89), nickel (75,79,90,91), niobium (92), rhodium (93,94), silver (95—97), tungsten (72,75—77,87,89), uranium (98), and vanadium (99). The coordination compounds formed from tertiary bismuthines are less stable than those formed from tertiary phosphines, arsines, or stibines. 

Liquid-Phase Epoxidation with Hydroperoxides. Molybdenum, vanadium, and tungsten have been proposed as Hquid-phase catalysts for the oxidation of the ethylene by hydroperoxides to ethylene oxide (205). tert- uty hydroperoxide is the preferred oxidant. The process is similar to the arsenic-catalyzed route, and iacludes the use of organometaUic complexes. 

The ability of metal ions to form complexes with formazans is utilized to determine these ions either directly (for low valent reducing ions) or indirectly in the presence of a reducing agent. Among others, molybdenum(VI) and vanadium(V) have been determined using this method.442,443 Indirect methods have been reported for the analyses of substances that do not reduce tetrazolium salts. Examples include arsenic in nickel ores436 and traces of selenium.437 A method for the extraction and analysis of a number of metal ternary ion association complexes has been described.444 - 448... 

The complex of tartaric acid and antimony (emetic) was described three centuries ago. Nevertheless, the structure of this compound has been elucidated these last fifteen years by X-ray diffraction ( 1 ). In fact, emetic presents a binuclear cyclic structure. Many authors mentioned similar complex with transition metals (vanadium (2), chromium (3)) or metalloids (arsenic (4), bismuth (5)). Emetic with phosphorus was not mentioned. Nevertheless, tartaric acid or alkyl tartrates has been utilized in phosphorus chemistry tartaric acid reacts with trialkyl phosphites giving heterocyclic phosphites (6). Starting from alkyl tartrates, we prepared spirophosphoranes with a P-H bond and sixco-ordinated compounds (7). With unprotected tartaric acid, many possibilities appear condensation as a diol, as a di(oc-hydro-xyacid), or even as a 8-hydroxyacid. 

For the analysis of complex tungstates containing arsenic, antimony, or vanadium, see Sweeney, J. Amor. Chem. Soc., 1916, 38, 2377. 

Tungsten and Nitrogen, Phosphorus, Arsenic, Antimony, and Bismuth—Complex Salts containing Vanadium—Carbides—Complex Cyanogen Derivatives— Compounds with Silicon, Titanium, 2areonium, and Boron. 

Chemical leach tests of the <50 p.m size fraction of dust samples collected around Owens Lake, using water (Reheis etal, 2001, and our unpublished data) and SLFs (our unpubhshed data), show that the dusts are sufficiently aUcahne and reactive to shift the pH of water and SLF to values near 10.5 and 9.5, respectively. Arsenic, chromium, vanadium, molybdenum, hthium, zinc, and other trace metals or metalloids are readily solubilized from the dusts. The trace metals or metalloids leached in the greatest quantities are those that form oxyanion species or abundant carbonate complexes in solution, and that are therefore mobilized most effectively under the alkaline conditions generated by the alkaline dusts. 

Arsenic, like phosphorus and vanadium, forms finite oxo-anions but the oxygen chemistry of Sb is quite different, being based not on the tetrahedral but the octahedral co-ordination of Sb" by oxygen. There are two main groups of these oxo-complexes ... 

Weak complexes form between vanadate and phosphate, 9,99 pyrophosphate,59 arsenate,59 and chromate.106 The formation constant for the simple phosphovanadate is about 20 M 1." Structural characterization has been reported for interesting cluster structures of vanadium with organophosphonates107 and with sulfate.108 Divanadium(V) complexes with either monodentate or bidentate nitrate (N03 ) groups have been reported.109... 

Tungsten resembles molybdenum in showing a remarkable ability to form complex compounds. One molecule of an alkali oxide may be combined with 1, 2, 3, 4, 5, 6, or 8 molecules of WO3 while more complex molecules may contain as much as 5Mr20 condensed with varying amounts of WOa. There are also formed many series of complex tungstates in which W03 combines with varying proportions of the oxides of silicon, phosphorus, arsenic, antimony, vanadium, and boron,... 

Vanadium(IV) complexes, 487 acetates, 513 acetylacetonates, 504 electrochemistry, 505 ESR spectra, 505 adenine, 568 adipates, 516 alcohols, 502 amines, 489 amino adds, 544 equilibria, 544 ammonia, 489 arsenates, 513 arsenic ligands, 496 arsines, 498 ascorbic add, 502 benzilato, 522 biguanide, 496 binucleating ligands, 561 bipyridyl, 492,494... 

Oxo-vanadium(IV) complexes and oxo-vanadium(V) complexes have been prepared from HN[(P(Ph2) = NR]2 (R = Ph, SiMe3) and VO(acac)2 (acac = acetylacetonato) or VOCI3. The preparation of spirocyclic arsenic(III) and antimony(III) complexes with general formula N[(P(Ph2) = NR]2M0R 0 (R = Ph, SiMe3 R = ethylene or propylene (whether or not alkyl-substituted) has been reported. Spectroscopic methods have been used for the characterization of these products. 

The uranyl vanadates form mineral groups distinct from the phosphates and arsenates because of the markedly different chemistry of the vanadium ion. Like uranium, vanadium shows several valence states in nature, and its detailed mineralogy is very complex. The crystal chemistry of vanadium was reviewed by Evans.In its lower valence states it forms distinct vanadium minerals, but in its higher valence state 5-1- it com-... 

In acid leaching, sulphuric acid is used in a complex ion-exchange or solvent extraction process to produce yellowcake of very high purity. Various metals (such as vanadium, arsenic, nickel, iron, copper, etc.) may be leached in this process. Chemicals involved in this process include sulphuric acid, ammonium nitrate, sodium chloride, amines, alcohols, kerosene, and ammonia. Considerable process water has to be derived from reclaim water of the tailings and returned to the mine for preparing the slurry. 

Inorganic Derivatives.- 1,6-Anhydro 2-chloro-2,4-dideoxy-4-(diphenylphosphoryl)-P-D-glucopyranose, the P-in-the-ring sugar analogues (27) and (28)," the natural arsenic-containing riboside (29), methyl 4,6-0-benzylidene-3-deoxy-3-C-triphenylstannyl-a-D-altropyranoside, two isomeric chromium(III) complexes with 1,3,5-triamino-1,3,5-trideoxy-cw-inositol in the one structure, the vanadium(in) complex (30),and the platinum(Il)-dithiocarbamate complex (31). ... 

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