. "2"^^ . . . "[390E13C9B0B3]" . "Studovali jsme oxida\u010Dn\u00ED vlastnosti niobu a c\u00EDnu v mesopor\u00E9zn\u00EDch matric\u00EDch p\u0159i oxidac\u00EDch cyklick\u00FDch keton\u016F, cyklick\u00FDch alken\u016F a cyklick\u00FDch alkenon\u016F s pou\u017Eit\u00EDm peroxidu vod\u00EDku jako oxida\u010Dn\u00EDho \u010Dinidla. P\u0159i synt\u00E9ze mesopor\u00E9zn\u00EDch molekulov\u00FDch s\u00EDt typu MCM-41 a MCM-48 byli niob a c\u00EDn za\u010Dlen\u011Bny do struktury. Rentgenov\u00E1 difrak\u010Dn\u00ED anal\u00FDza a sorp\u010Dn\u00ED izotermy dus\u00EDku potvrdily vysokou kvalitu t\u011Bchto mesopor\u00E9zn\u00EDch molekulov\u00FDch s\u00EDt, dokonce i po za\u010Dlen\u011Bn\u00ED Nb a/ nebo Sn. Uk\u00E1zalo se, \u017Ee niob selektivn\u011B oxiduje dvojnou vazbu substr\u00E1tu za vzniku epoxidu, n\u00E1sledn\u011B doch\u00E1z\u00ED ke kroku vedouc\u00EDmu k hydrataci a vzniku diol\u016F a ketodiol\u016F. Na druh\u00E9 stran\u011B c\u00EDn vede k Baeyerov\u011B-Villigerov\u011B oxidaci cyklick\u00FDch keton\u016F na laktony bez n\u00E1sledn\u00FDch reakc\u00ED, zat\u00EDmco niob je v t\u011Bchto reakc\u00EDch neaktivn\u00ED. V p\u0159\u00EDpad\u011B, kdy substr\u00E1t nese na stejn\u00E9m kruhu jak C=C dvojnou vazbu tak karbonylovou skupinu, niob p\u0159ednostn\u011B oxiduje dvojnou vazbu s mnohem v\u011Bt\u0161\u00ED aktivitou ne\u017E c\u00EDn."@cs . "414367" . . "mesoporous molecular sieves; niobium; tin; synthesis; oxidation properties"@en . "9"^^ . . . "Oxidation properties of niobium and tin in mesoporous matrices were investigated in oxidation of cyclic ketones, cyclic olefins and cyclic ketonolefins with hydrogen peroxide as an oxidation agent. Mesoporous molecular sieves of MCM-41 and MCM-48 types were synthesezed and niobium and tin were incorporated into the structure. X-ray diffraction and nitrogen sorption isotherms confirmed a high-quality of these mesoporous molecular sives even after incorporation of Nb and/or Sn. It was shown that niobium selectively oxidizes double bond of the substrates to epoxide followed by further hydration and forms diols and keto-diols in the second step of the reaction. When substrate contains both C=C double bond and carbonyl group on the same ring. Nb oxidizes preferentially the double bond with a much higher activity than Sn." . "4"^^ . "Comparison of oxidation properties of Nb and Sn in mesoporous molecular sieves" . . . "P(1ET400400413), P(FT-TA/040), Z(AV0Z40400503)" . . "Feliczak, A." . "Srovn\u00E1n\u00ED oxida\u010Dn\u00EDch vlastnost\u00ED Nb a Sn v mesopor\u00E9zn\u00EDch molekulov\u00FDch s\u00EDtech"@cs . . "Nowak, I." . . "\u010Cejka, Ji\u0159\u00ED" . "Comparison of oxidation properties of Nb and Sn in mesoporous molecular sieves"@en . "321" . . "Applied Catalysis A - General" . "Nekoksov\u00E1, Iveta" . "Comparison of oxidation properties of Nb and Sn in mesoporous molecular sieves"@en . "Comparison of oxidation properties of Nb and Sn in mesoporous molecular sieves" . "Srovn\u00E1n\u00ED oxida\u010Dn\u00EDch vlastnost\u00ED Nb a Sn v mesopor\u00E9zn\u00EDch molekulov\u00FDch s\u00EDtech"@cs . . "Oxidation properties of niobium and tin in mesoporous matrices were investigated in oxidation of cyclic ketones, cyclic olefins and cyclic ketonolefins with hydrogen peroxide as an oxidation agent. Mesoporous molecular sieves of MCM-41 and MCM-48 types were synthesezed and niobium and tin were incorporated into the structure. X-ray diffraction and nitrogen sorption isotherms confirmed a high-quality of these mesoporous molecular sives even after incorporation of Nb and/or Sn. It was shown that niobium selectively oxidizes double bond of the substrates to epoxide followed by further hydration and forms diols and keto-diols in the second step of the reaction. When substrate contains both C=C double bond and carbonyl group on the same ring. Nb oxidizes preferentially the double bond with a much higher activity than Sn."@en . . . . . "40;48" . . "RIV/61388955:_____/07:00081228!RIV07-AV0-61388955" . "RIV/61388955:_____/07:00081228" . . "1" . . "0926-860X" . . "NL - Nizozemsko" .