Laureano Canoira

Catalytic production of biodiesel from soy-bean oil, used frying oil and tallow

Abstract Three fatty materials, soy-bean oil, used frying oil and tallow, were transformed into two different types of biodiesel, by transesterification and amidation reactions with methanol and diethylamine respectively. The ignition properties of these types of biodiesel were evaluated calculating the cetane index of the transesterification products, and the blending cetane number of the amide biodiesel blended with conventional diesel. Amide biodiesel enhances the ignition properties of the petrochemical diesel fuel, and it could account for the 5% market share that should be secured to biofuels by 2005.

Trimerization of isobutene over Amberlyst-15 catalyst

Abstract The purpose of this investigation is to study the oligomerization of isobutene over Amberlyst-15 catalyst in a mixed gas–liquid phase. Reaction conditions were optimised in order to maximise triisobutylene selectivity. Results show that more than 90% (w/w) triisobutylene was present in the final oligomer mixture.

Continuous elimination of Pb2+, Cu2+, Zn2+, H+ and NH4+ from acidic waters by ionic exchange on natural zeolites

A study of breakthrough curves for cations usually found in acid mine drainage (Pb(2+), Cu(2+), Zn(2+) and H(+)) and municipal wastewater (NH(4)(+)) have been conducted on some natural zeolitic tuffs. The zeolitic tuffs used in this study are: three zeolitic tuffs from Cayo Formation, Guayaquil (Ecuador), characterized by X-ray diffraction as clinoptilolite (sample CLI-1) and heulandite (samples HEU-1 and HEU-2)-rich tuffs, and two zeolitic tuffs from Parnaiba Basin, Belem do Pará (Brazil), characterized as stilbite-rich tuffs (samples STI-1 and STI-2). The clinoptilolite sample CLI-1 shows an exceedingly good exchange capacities for Pb(2+) and NH(4)(+) as received, and also a very high exchange capacity for Cu(2+) and Zn(2+) when conditioned with 2M sodium chloride, with much higher values than those reported in the literature for other clinioptilolite ores. A general order of effective cation exchange capacity could be inferred from breakthrough curves on these zeolitic tuffs: CLI-1 > HEU-2 > HEU-1 > STI-2. Since it is true for most of the cations studied.

Air oxidation of ethylbenzene catalysed by bis(acetylacetonate)nickel(II) and 1-n-butyl-3-methylimidazolium hexafluorophosphate

Abstract In this paper some aspects of the liquid-phase oxidation of ethylbenzene with air catalysed by Ni 2+ complexes have been studied; the use of a nickel soluble complex without acetylacetone ligands gave unsatisfactory results. Quaternary ammonium salts (R 4 NBF 4 ) (R= n -Bu, Me) were used as co-catalysts, and the ammonium salt with the longer radical n -Bu gave better results. On the other hand, a catalytic system has been designed based on Ni(acac) 2 and 1- n -butyl-3-methylimidazolium hexafluorophosphate and its reactivity has been explored in the oxidation with air of ethylbenzene at atmospheric pressure, showing that this catalytic system could be at the moment an alternative to the catalysts in use for this oxidation process. A new analytical procedure based on FT-IR spectroscopy to analyse the main reaction by-products, methylphenyl carbinol and acetophenone has also been described.

Electron impact mass spectrometry of indole derivatives

Abstract The electron impact mass spectra of 51 compounds, grouped in five series, containing the indole ring, some of them of potential pharmacological interest, have been studied, and their fragmentation patterns have been proposed on the basis of metastable studies and accurate mass measurements.

Gas-Phase Synthesis of Ethyl tert-Butyl Ether (ETBE) on H-ZSM-5 Catalyst in Continuous Fixed-Bed and Fluidized-Bed Reactors

The gas-phase synthesis of ETBE from ethanol and isobutene has been carried out over a H-ZSM-5 catalyst in two types of continuous-flow catalytic reactors, fixed-bed and fluidized-bed. We have studied the influence of temperature, molar ratio ethanol/isobutene and weight hourly space velocity on the yield of ETBE.

Synthesis of 1-tert-butoxy-2-propanol (PGTBE) from propylene glycol and isobutene in a packed trickle-bed reactor on acid catalysts

Abstract 1- tert -Butoxy-2-propanol has been synthesized from propylene glycol and isobutene over two solid acid catalysts, montmorillonite and Amberlyst 15, in a packed trickle-bed reactor operating under different experimental conditions, and its antiknock properties as an oxygenate gasoline additive have been evaluated. The reaction on Amberlyst 15 fitted first-order kinetics for isobutene ( k ′=0.37 h −1 ) for a molar ratio propylene glycol to isobutene of one.

Synthesis of biphenyl derivatives by coupling reaction of halobenzenes with organonickel (0) complexes

A study of the coupling reaction of substituted halobenzenes with a zero valent pyridine-nickel complex as catalyst, leading to biphenyl derivatives, has been made. Electron-releasing groups as substituents favor the formation of coupling products in low yields, while electron-withdrawing groups as substituents suppress the formation of dimers.AbstractИследовали реакцию присоединения замещенных галогенбензолов к безвалентным комплексам никеля с пиридином, являющимся катализатором, приводя к образованию производных бифенила. Эпектронодонорные группы благоприятствуют образованию продуктов присоединения с небольшими выходами, в то время как электроноакцепторнье группы предотвращают образование димеров.

Diastereotopic effect of the methylene protons in N-ortho-substituted-N-β-cyanoethylanilides: X-ray structure of N-(β-cyanoethyl)-2′-chloromaleanilic acid

Some N-β-cyanoethyl-ortho-substituted anilides show a diastereotopic coupling effect of the methylene protons of the N-β-cyanoethyl chain in the 1H n.m.r. spectra. Resolution of those proton coupling systems have been done by computational methods and their analyses indicate that in chloroform solution the gauche conformation is preferred in all those compounds. The solid-state X-ray analysis of (2) also shows that this is in a special gauche conformation. The diasterotopic effect can be seen as restricted rotational freedom of the alkyl chain in ortho-substituted compounds. However, an internal linkage between an N-α-proton of the chain and the CO amide group seems to be the common anchorage of the α-methylene, while the β-methylene protons are fixed by steric and dipole effects.

Electron impact mass spectrometry of oxindole, pseudoindoxyle and indolenine derivatives

Abstract The electron impact mass spectra of 22 compounds, grouped in five series, containing the oxindole, pseudoindoxyle and indolenine rings, some of them with potential pharmacological interest, have been studied, and their fragmentation patterns have been proposed on the basis of metastable studies, accurate mass measurements and fragmentation schemes upon electron impact of structurally related alkaloids.