- Ionic ammonium and anilinium based polymolybdate hybrid catalysts for olefin epoxidation
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Ionic polymolybdate hybrids (IPH) are interesting catalysts for liquid phase olefin epoxidation with tert-butylhydroperoxide; (tbhp), e.g. conversion of terpenic and fatty acid methyl ester (FAME) components of biomass to useful bio-products. IPHs may be easily prepared, under clean, mild, aqueous phase conditions. The type of organic precursor and the synthesis conditions influence the structural features of the IPHs. In this work, IPH epoxidation catalysts possessing one- (1-D) or two-dimensional (2-D) structures were investigated, which included the new materials 1-D methylammonium ammonium trimolybdate [Mo3O10?CH3NH3·NH4] (1) and 2-D bis(2,5-dimethylanilinium) pentamolybdate [Mo5O16?2(NH3C6H3(CH3)2)] (4) with solved structures, and 1-D bis(3,5-dimethylanilinium) trimolybdate [Mo3O10·2(NH3C6H3(CH3)2)] (2), bis(4-methylanilinium) trimolybdate [Mo3O10·2(NH3C6H4CH3)] (3), 2-D bis(anilinium) pentamolybdate [Mo5O16?2(NH3C6H5)] (5), bis(4-methylanilinium) pentamolybdate [Mo5O16?2(NH3C6H4CH3)] (6) and bis(4-ethylanilinium) pentamolybdate [Mo5O16?2(NH3C6H4C2H5)] (7). Systematic characterisation and catalytic studies helped gain insights into structure-activity relationships. The best-performing catalyst (2) was effective for the epoxidation of the FAMEs such as, methyl oleate which gave 92% methyl 9,10-epoxyoctadecanoate yield, at 99% conversion, at 70 °C. The reaction conditions (temperature, type of cosolvent and oxidant) influenced the catalytic reaction. Catalytic performance in consecutive batch runs was steady, and the structural features were essentially preserved.
- Bo?ek, Barbara,Neves, Patrícia,?asocha, Wies?aw,Valente, Anabela A.
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- Controlling Selectivity in Alkene Oxidation: Anion Driven Epoxidation or Dihydroxylation Catalysed by [Iron(III)(Pyridine-Containing Ligand)] Complexes
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A highly reactive and selective catalytic system comprising Fe(III) and macrocyclic pyridine-containing ligands (Pc-L) for alkene oxidation by using hydrogen peroxide is reported herein. Four new stable iron(III) complexes have been isolated and characterized. Importantly, depending on the anion of the iron(III) metal complex employed as catalyst, a completely reversed selectivity was observed. When X=OTf, a selective dihydroxylation reaction took place. On the other hand, employing X=Cl resulted in the epoxide as the major product. The reaction proved to be quite general, tolerating aromatic and aliphatic alkenes as well as internal or terminal double bonds and both epoxides and diol products were obtained in good yields with good to excellent selectivities (up to 93 % isolated yield and d.r.=99 : 1). The catalytic system proved its robustness by performing several catalytic cycles, without observing catalyst deactivation. The use of acetone as a solvent and hydrogen peroxide as terminal oxidant renders this catalytic system appealing.
- Tseberlidis, Giorgio,Demonti, Luca,Pirovano, Valentina,Scavini, Marco,Cappelli, Serena,Rizzato, Silvia,Vicente, Rubén,Caselli, Alessandro
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p. 4907 - 4915
(2019/08/30)
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- Catalytic transformation of (-)-limonene oxide over binary oxide catalysts of alumina rare earths
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The transformation reaction of (-)-limonene oxide over single oxides like Al2O3, Y2O3, Nd2O3, Sm2O3, Eu2O3 and binary oxides like Al2O3-Y2O3, Al2O3-Sm2O3, Al2O3-Eu2O3 Al2O3-Pr6O11 and Al2O3-Nd2O3 are discussed. The catalysts show selectivity for allyl alcohol formation. trans-exo-Carveol (2) and cis-endo- carveol (3) are the major products formed at 140°C and 110°C respectively.
- Jayasree
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p. 765 - 768
(2007/10/03)
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- New entry to a cis-fused bicyclic ring system by a sigmatropic rearrangement via cyclic allylsulfonium ylides. Synthesis of the cis-2-oxa-9-vinyldecalin skeleton
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Rhodium(II) acetate-catalysed cyclisation of methyl 2-diazo-5--3-oxopentanoate 4 proceeded in a stereoselective fashion to provide in a high yield cis-2-oxa-9-vinyldecalin derivative 5, the
- Kido, Fusao,Abiko, Toshiya,Kato, Michiharu
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p. 2989 - 2994
(2007/10/03)
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