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Browsing by Author "Nunes, Ana V. M."

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  • Cyclic carbonate synthesis from CO2 and epoxides using zinc(II) complexes of arylhydrazones of beta-diketones
    Publication . Moreno Montoya, Carmen Alicia; Gomez, Clara F.; Paninho, Ana B.; Nunes, Ana V. M.; Mahmudov, Kamran; Najdanovic-Visak, Vesna; Martins, Luisa; Guedes Da Silva, M. Fátima C.; Pombeiro, Armando; Nunes Da Ponte, Manuel
    Zinc(II) complexes of arylhydrazones of beta-diketones (AHBD) were used for the first time as catalysts combined with tetrabutylammonium bromide (TBABr), in the coupling reaction between CO2 and epoxides. The influence of pressure and temperature on cyclic carbonate formation was investigated, as well as the catalytic activity toward different substrates (e.g. styrene oxide, propylene oxide and cyclohexene oxide). The molar ratio between metal complex and TBABr was determined for maximum catalytic activity.
    2016-03Journal article Restricted access Show more
  • Mn-II and Cu-II complexes with arylhydrazones of active methylene compounds as effective heterogeneous catalysts for solvent- and additive-free microwave-assisted peroxidative oxidation of alcohols
    Publication . Mahmudov, Kamran; Sutradhar, Manas; Martins, Luisa; Silva, Maria de Fátima C. Guedes da; Ribera, Alice; Nunes, Ana V. M.; Gahramanova, Shahnaz; Marchetti, Fabio; Pombeiro, Armando
    A one-pot template reaction of sodium 2-(2-(dicyanomethylene) hydrazinyl) benzenesulfonate (NaHL1) with water and manganese(II) acetate tetrahydrate led to the mononuclear complex [Mn(H2O)(6)](HL1a)(2)center dot 4H(2)O (1), where (HL1a) -= 2-(SO3-)C6H4(NH)=N=C(C N) (CONH2) is the carboxamide species derived from nucleophilic attack of water on a cyano group of (HL1) . The copper tetramer [Cu-4(H2O)(10)(-) (1 kappa N: kappa O-2: kappa O, 2 kappa N: k(O)-L-2)(2)]center dot 2H(2)O (2) was obtained from reaction of Cu(NO3)(2)center dot 2.5H(2)O with sodium 5-(2( 4,4-dimethyl-2,6-dioxocyclohexylidene) hydrazinyl)-4-hydroxybenzene-1,3-disulfonate (Na2H2L2). Both complexes were characterized by elemental analysis, IR spectroscopy, ESI-MS and single crystal X-ray diffraction. They exhibit a high catalytic activity for the solvent-and additive-free microwave (MW) assisted oxidation of primary and secondary alcohols with tert-butylhydroperoxide, leading to yields of the oxidized products up to 85.5% and TOFs up to 1.90 x 103 h(-1) after 1 h under low power (5-10 W) MW irradiation. Moreover, the heterogeneous catalysts are easily recovered and reused, at least for three consecutive cycles, maintaining 89% of the initial activity and a high selectivity.
    2015Journal article Restricted access Show more