A nuclear magnetic resonance (1H and 13C) and isotope ratio mass spectrometry (delta13C, delta2H and delta18O) study of Andalusian olive oils.

We have determined delta(13)C, delta(2)H and delta(18)O isotopic abundances in Andalusian olive oils. In addition, the fatty acid composition and the distribution of isomers at positions 1,3 and 2 of glycerol were determined by (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopy, respectively. Isotopic results obtained for four series of oil samples extracted from olives harvested in the 2004/05 and 2005/06 seasons are discussed in terms of olive variety, ripeness, geographical origin, fatty acid composition and growing altitude. A distinction was also established between olives grown in irrigated and in dry land by studying selected samples of the previous series and others from the 2005/06, 2006/07, 2007/08 and 2008/09 seasons. The results showed that olive ripeness does not influence the abundance of any of the three isotopes studied. On the other hand, the olive variety influences the abundance of the oxygen and hydrogen isotopes, and also, less markedly, that of carbon. No clear-cut effect of height or latitude on isotope values is observed, probably because the olive variety also changes with height and latitude, thus masking such influences. The oil samples from dryland-grown olives had increased delta(13)C values relative to irrigation-grown olives. In addition, no definite relationship appears to exist between isotope distribution and fatty acid composition. Finally, oil samples from olives harvested in the 2005/06 season in Italy could be distinguished from those from Spain in terms of their isotopic values (delta(2)H mainly).

A study on the potential application of natural phosphate in photocatalytic processes.

In an attempt at increasing surface area of the resulting solids, different titanium-based systems were synthesized on natural phosphate through the sol-gel process using diverse ageing conditions (reflux, magnetic stirring, sonication or microwaves) and tested for gas-phase selective photooxidation of propan-2-ol. The best results were obtained for the system aged under ultrasounds which was ascribed to its lower band-gap energy. Moreover, the synthesis of TiO(2) on natural phosphate seemed to produce retardation in crystallization as well as a change in titanium and phosphorus electronic environments (as determined by XPS) which in the case of the sonicated system resulted in an improved catalytic behavior as compared to pure titania. All in all, the present piece of research shows that provided that its surface area can be increased natural phosphate can be used as support for a photocatalytic active phase thus widening the scope of its application.

Oxygen-18 measurement of Andalusian olive oils by continuous flow pyrolysis/isotope ratio mass spectrometry.

We report a method for the determination of delta(18)O isotopic abundance in olive oils. The results obtained by applying the method to various Andalusian oil samples obtained in the 2004/05 and 2005/06 seasons are discussed in relation to olive variety, geographical origin, climate and ripeness index. Application of the method to samples of assured varietal purity exposed the influence of olive variety and origin but not of the ripeness index. The delta(18)O values for the 2005/06 season are higher on average than those obtained in the colder 2004/05 season. Results obtained for samples of the Picual and Hojiblanca varieties in Córdoba and Málaga in the 2005/06 season suggest a correlation between enrichment in heavy isotopes and latitude whereas no clear-cut effect of altitude was observed.

Poly(ethylene oxide)-based surfactants as templates for the synthesis of mesoporous silica materials.

Various mesoporous silica solids were prepared by using poly(ethylene oxide)-based surfactants as templates in a neutral, fluoride, or moderately acidic medium, and their properties examined by different physical techniques. Precipitation in an acid or neutral medium provided materials of pore size in between those of micropores and mesopores irrespective of the molecular size of the surfactant. On the other hand, syntheses in a fluoride-containing medium yielded mesoporous materials with pore diameters over the range 36-84 A that increased with increasing surfactant size. All materials possessed specific surface areas above 650 m(2)g(-1) and high pore volumes-particularly those obtained in a fluorinated medium. The conditions used in the syntheses and the fact that all produced highly disordered porous materials suggest that their mechanism of formation is essentially of the N(0)I(0) neutral type. The materials obtained in the presence of fluoride ion, which promote the condensation of siliceous species, retain greater amounts of surfactant and exhibit increased cross-linking and decreased particle sizes, which results in textural mesoporosity.

Synthesis and Characterization of Basic Catalysts Based on Sodium-Magnesium Mixed Phosphates and Their Use in the Conversion of 2-Hexanol.

Various catalysts consisting of sodium-magnesium mixed orthophosphates were synthesized and characterized in structural terms using X-ray diffraction, thermogravimetric analysis, differential thermal analysis, diffuse reflectance infrared spectroscopy, and solid-state (31)P NMR spectroscopy. In addition, the surface properties of the solids were determined from N(2) adsorption-desorption isotherms and their chemical properties characterized with various titrants. One of the solids obtained consists of NaMgPO(4)/Mg(2)P(2)O(7) and the rest of NaMgPO(4)/MgO. Their surface chemical properties vary depending on the particular synthetic procedure used; thus, the NaMgPO(4)/MgO systems exhibit similar populations of acid and basic sites, whereas the NaMgPO(4)/Mg(2)P(2)O(7) systems contain many more acid sites than basic sites. All the solids obtained exhibit substantial dehydrogenating activity in the conversion of gaseous 2-hexanol; in fact, some of the NaMgPO(4)/MgO systems are even more active and selective than a MgO solid tested under identical reaction conditions. Copyright 2001 Academic Press.

Activity of Basic Catalysts in the Meerwein-Ponndorf-Verley Reaction of Benzaldehyde with Ethanol.

The Meerwein-Ponndorf-Verley (MPV) reaction of benzaldehyde with ethanol in the liquid phase in the presence of basic catalysts consisting of magnesium oxide, calcium oxide, and mixed oxides obtained by calcination of layered double hydroxides, was studied. The catalysts were characterized using various techniques including X-ray diffraction and gas adsorption (viz nitrogen physisorption to determine textural properties and carbon dioxide chemisorption to elucidate surface basic properties). The catalyst consisting of calcium oxide, which was that possessing the highest density of basic sites, was found to be the most active in the process; the MPV reaction was accompanied by two other, competing reactions (viz aldol condensation and the Tishchenko cross-reaction). The MPV reaction of benzaldehyde with other alcohols was also examined, the highest conversion being obtained with secondary alcohols as hydrogen sources. Copyright 2001 Academic Press.

Electrospray Ionization Mass Spectrometry Detection of Intermediates in the Palladium-Catalyzed Oxidative Self-Coupling of Areneboronic Acids.

Several intermediates of the oxidative coupling of areneboronic acids to afford biaryls have been identified by electrospray ionization mass spectrometry. Knowledge has been gained about the steps occurring after the biaryl formation and leading to the recovery of the catalytic species.