43 documents found, page 1 of 5
A silicododecamolybdate/pyridinium-tetrazole hybrid molecular salt as a catalys...
Nunes, Martinique S.; Neves, Patricia; Gomes, Ana C.; Cunha-Silva, Luis; Lopes, Andre D.; Valente, Anabela A.; Pillinger, Martyn; Goncalves, Isabel S.The hybrid polyoxometalate (POM) salt (Hptz)(4)[SiMo12O40].nH(2)O (1) (ptz = 5-(2-pyridyl)tetrazole) has been prepared, characterized by X-ray crystallography, and examined as a catalyst for the epoxidation of cis-cyclooctene (Cy) and bio-derived olefins, namely dl-limonene (Lim; a naturally occurring monoterpene found in the rinds of citrus fruits), methyl oleate and methyl linoleate (fatty acid methyl esters ...
Desulfurization of diesel by extraction coupled with Mo-catalyzed sulfoxidation...
Juliao, Diana; Gomes, Ana C.; Pillinger, Martyn; Lopes, Andre D.; Valenca, Rita; Ribeiro, Jorge C.; Goncalves, Isabel S.; Balula, Salete S.Oxidative desulfurization (ODS) is a method of removing sulfur from diesel fuel that has the potential to complement or even replace conventional hydrodesulfurization processes in oil refineries. One of the most promising variants of ODS is extractive and catalytic ODS (ECODS) in which the organic sulfur compounds in the liquid fuel are oxidized and extracted in situ from the oil phase into an extractant phase....
Dichlorodioxomolybdenum(VI) complexes bearing oxygen-donor ligands as catalysts...
Juliao, Diana; Gomes, Ana C.; Cunha-Silva, Luis; Pillinger, Martyn; Lopes, Andre D.; Valenca, Rita; Ribeiro, Jorge C.; Goncalves, Isabel S.The complexes [MoO2Cl2(DMB)(2)] (1) and [MoO2Cl2(DEO)] (2) (DMB = N,N-dimethylbenzamide, DEO = N,N'-diethyloxamide) have been evaluated as catalysts in extractive-catalytic oxidative desulfurization (ECOD) of a simulated diesel fuel. Using the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) as extraction solvent and H2O2 as oxidant, ultra-deep desulfurization (S-content from 3000 ppm to...
A hydrogen-bonded assembly of cucurbit[6]uril and [MoO2Cl2(H2O)(2)] with cataly...
Nogueira, Lucie S.; Antunes, Margarida M.; Gomes, Ana C.; Cunha-Silva, Luis; Pillinger, Martyn; Lopes, Andre D.; Valente, Anabela A.The reaction of the macrocyclic cavitand cucurbit[6]uril (CB[6]) and the diaqua complex [MoO2Cl2(H2O)(2)] in hydrochloric acid solution gave a water insoluble supramolecular compound with the general composition 2[MoO2Cl2(H2O)(2)]center dot CB[6]center dot xH(2)O center dot yHCl center dot z(CH3COCH3) (2). Single crystal X-ray diffraction (XRD) analysis revealed the presence of barrel-shape supramolecular entit...
Oxidomolybdenum complexes for acid catalysis using alcohols as solvents and rea...
Gomes, Ana C.; Neves, Patricia; Cunha-Silva, Luis; Valente, Anabela A.; Goncalves, Isabel S.; Pillinger, MartynThe application field of dichloridodioxidomolybdenum (VI) chelate complexes, which have been intensively investigated as catalysts for liquid-phase olefin epoxidation, is broadened to encompass acid catalysis, in particular, alcoholysis and acetalisation reactions. Complex [MoO2Cl2(L)] (1) with L = 4,4'-di-tert-butyl-2,2'-bipyridine was chosen as (pre)catalyst. Depending on the reaction conditions, 1 either rem...
Metal oxide-triazole hybrids as heterogeneous or reaction-induced self-separati...
Amarante, Tatiana R.; Neves, Patricia; Valente, Anabela A.; Almeida Paz, Filipe A.; Pillinger, Martyn; Goncalves, Isabel S.The hybrid metal oxide-triazole materials [MoO3(trz)(0.5)] (1) and [W2O6(trz)] (2) (trz = 1,2,4-triazole) have been hydrothermally synthesized and characterized by different techniques (TGA, SEM, H-1 and C-13 MAS NMR, FT-IR spectroscopy, and structure determination by Rietveld analysis of high resolution synchrotron powder XRD data). Materials 1 and 2 display distinct behaviors when applied as catalysts for oxi...
A recyclable ionic liquid-oxomolybdenum(VI) catalytic system for the oxidative ...
Juliao, Diana; Gomes, Ana C.; Pillinger, Martyn; Valenca, Rita; Ribeiro, Jorge C.; Goncalves, Isabel S.; Balula, Salete S.The oxidative desulfurization of model and real diesel has been studied using the complex [MoO2Cl2(4,4'-di-tert-butyl-2,2'-bipyridine)] as (pre)catalyst, aq. H2O2 as oxidant, and an ionic liquid as extraction solvent. Under moderate conditions (50 degrees C) and short reaction times (<3 h), dibenzothiophene, 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene could be completely removed from the model die...
Solid-state study of the structure and host-guest chemistry of cucurbituril-fer...
Gomes, Ana C.; Magalhaes, Clara I. R.; Oliveira, Tania S. M.; Lopes, Andre D.; Goncalves, Isabel S.; Pillinger, MartynInclusion complexes of ferrocene (Fc) with cucurbit[n]urils (n = 7, 8) have been prepared via a rapid microwave-assisted hydrothermal approach. Solids were isolated and characterised by elemental analysis, powder X-ray diffraction (PXRD), spectroscopic, and thermoanalytical methods. The UV-Vis spectra support the presence of Fc in Fc@CB7 and a mixture of Fc and ferrocenium ions in Fc@CB8. Partial oxidation of F...
Catalytic Application of an Octamolybdate Salt (H(3)biim)(4)[beta-Mo8O26] in Ol...
Neves, Patricia; Amarante, Tatiana R.; Valente, Anabela A.; Pillinger, Martyn; Goncalves, Isabel S.The octamolybdate salt (H(3)biim)(4)[beta-Mo8O26] (1) has been prepared in good yield by hydrolysis of the complex [MoO2Cl2(H(2)biim)] (H(2)biim = 2,2'-biimidazole). Compound 1 showed a good performance as a (pre)catalyst for the epoxidation of olefins using either tert-butylhydroperoxide (TBHP) or hydrogen peroxide as oxidant. With the ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)...
Catalytic alcoholysis of epoxides using metal-free cucurbituril-based solids
Bruno, Sofia M.; Gomes, Ana C.; Oliveira, Tania S. M.; Antunes, Margarida M.; Lopes, Andre D.; Valente, Anabela A.; Goncalves, Isabel S.Metal-free cucurbit[7]uril (CB7) solid-state assemblies promote acid-catalysed alcoholysis of aliphatic and aromatic epoxides under mild conditions to give beta-alkoxy alcohols, which are important intermediates for the synthesis of a vast range of compounds such as bioactive pharmaceuticals. The catalytic process is heterogeneous and the catalyst can be reused in consecutive runs without any reactivation treat...