Organic compounds -- part of the class 532-570 series – Organic compounds – Heavy metal containing
Patent
1998-04-23
2000-02-08
Nazario-Gonzales, Porfirio
Organic compounds -- part of the class 532-570 series
Organic compounds
Heavy metal containing
556 14, 502168, 502170, 502215, 502219, 502305, 502324, C07F 1500
Patent
active
060229861
DESCRIPTION:
BRIEF SUMMARY
The present invention describes the preparation of novel manganese-containing heteropolyoxometallates.
Polyoxometallates are inorganic metal-oxygen clusters comprising defined oligomeric or polymeric structural units and are formed spontaneously under suitable conditions from simple vanadium, niobium, tantalum, molybdenum or tungsten compounds in aqueous medium or in organic solvents (M. T. Pope, Heteropoly and Isopoly Oxometalates, Springer-Verlag Berlin, 1983).
Isopolyoxometallates are the simplest form of polyoxometallates and can be described as binary oxide anions [M.sub.m O.sub.y ].sup.p-. Typical examples are [Mo.sub.2 O.sub.7 ].sup.2- (m=2), [Mo.sub.6 O.sub.19 ].sup.2- (m=6), [W.sub.6 O.sub.24 ].sup.12- (m=6), [Mo.sub.36 O.sub.112 ].sup.8- (m=36). Polyoxometallates having the formula [X.sup.*.sub.x A.sub.a M.sub.m O.sub.y ].sup.p- contain one or more heteroatoms. These heteroatoms can be nonmetals, semimetals and/or even metals. X* is, for example, phosphorus in [PW.sub.12 O.sub.40 ].sup.3-, a classical anion of the Keggin structural type. Formal replacement of MO.sub.y structural units by heteroatoms makes it possible to introduce redox-active transition metal ions into the solid state structure.
Manganese-containing polyoxometallates are known. Among the lacuna structures, a distinction is made between, for example, Keggin anions [MnXM.sub.11 O.sub.39 ].sup.5- and anions of the Dawson structural type [MnX.sub.2 M.sub.17 O.sub.61 ].sup.7-/8- (J. Am. Chem. Soc. 109, 1987, 402 and J. Inorg. Nucl. Chem. 32, 1970, 3875) where M=Mo, W and X=P, Si, Ge and B. Within this class of compounds, the compounds K.sub.5 [PMnW.sub.11 O.sub.39 ] and K.sub.7 [BMnW.sub.11 O.sub.39 ] have been studied as catalysts for the epoxidation of olefins (J. Am. Chem. Soc. 117, 1995, 685). However, the catalytic activity of the manganese-containing polyoxometallates is very low compared to the unsubstituted free acid H.sub.3 [PW.sub.12 O.sub.40 ] or is virtually undetectable.
The compounds K.sub.6 [PW.sub.11 MnN.sub.3 O.sub.39 ] and K.sub.6 [SiMo.sub.11 MnO.sub.39 ] are used as catalysts for the liquid-phase oxidation of alkanes, but the second of these displays virtually no catalytic activity. Here, catalytic activities are achieved virtually only when vanadium and/or azide are present as promoters (EP-A-301 723, Table I).
Manganese-containing heteropolyoxometallates containing the heteroatoms X=S, Sb, Te, Bi and Se have not been known hitherto.
Only manganese-containing heteropolyoxometallates, i.e. manganese-heteropolyoxometallates without a further heteroatom, are known in only a few cases. Gazz. Chim. Ital. 98, 1968, 1197 mentions a heteropolyoxometallate containing divalent manganese as ammonium salt of the [MnMo.sub.6 O.sub.18 (OH).sub.6 ].sup.4- anion. No information is given about the properties of this compound or about the possibility of introducing manganese in higher oxidation states.
The potassium and ammonium salts of a heteropolyoxometallate containing tetravalent manganese, viz. [MnMo.sub. 9O.sub.32 ].sup.6- anion, have been described [J. Less-Common Metals 54, 1977, 289 and Acta Cryst. 7, 1954, 438]. This anion is obtained by oxidation of an aqueous Mn(II) salt solution with paramolybdate. The preparation of a sodium/potassium salt of the anion (MnW.sub.6 O.sub.24).sup.8- containing tetravalent manganese by reaction of sodium tungstate and manganese(II) sulfate with potassium peroxodisulfate in aqueous solution without addition of acid is described in Sov. J. Coord. Chem. 5. 1979, 740. In this case too, no information is given as to how a change in the oxidation state of the manganese can be achieved; in particular, a compound containing trivalent manganese is not known.
Polyoxometallates which are doped with not only manganese but also with a further transition metal zinc or cobalt are known from J. Am. Chem. Soc. 116, 1994, 5509. The compound [WZnMn.sub.2 (ZnW.sub.9 O.sub.34).sub.2 ].sup.12- is used as catalyst for the epoxidation of olefins with H.sub.2 O.sub.2 (J. Am. Chem. Soc. 117, 1995, 5066). This rea
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Bohner Rainer
Krebs Bernt
Scharbert Bernd
Schulz Rolf Peter
Thulig Christian
Hoechst Research & Technology Deutschland GmbH & Co. KG
Nazario-Gonzales Porfirio
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