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Gas-phase basicities (GB) of strong organic bases containing the imino group were re-examined in the light of the re-evaluated GB values for the reference bases given in a recent compilation of Hunter and Lias. Structural (internal) effects which influence the basicity are discussed and general relations for the GB prediction are proposed for simple alkyl amidines and guanidines. These relations were used for estimation of cyclization and intramolecular H-bonding effects. Copyright © 2000 John Wiley & Sons, Ltd.

Peroxotungstic acid and quaternary ammonium peroxotungstic salts when complexed to organophosphorus(V) ligands exhibit enhanced reactivity and selectivity in the epoxidation of unsaturated alcohols with hydrogen peroxide. The organophosphorus ligands contain the phosphoryl OP subunit as complexing moiety and are related to phosphine oxide, arylphosphonic acid and acidic phosphate ester. Allylic and cinnamic alcohols were examined under homogeneous and biphasic liquid-liquid conditions.

Silicalite embedded BiOx clusters were prepared both with and without Na using sodium silicate and tetraethylorthosilicate as silicium precursors. Catalysts with 3 and 5 wt% Bi were obtained. The MFI structure was established from XRD, TEM, and N2 adsorption measurements. No deterioration of the silicalite framework by bismuth was observed. Bi exists as BiOx clusters as evidenced from XPS and EXAFS characterization. These clusters are localized inside the silicalite channels. Py-FTIR measurements indicated that 5wt% Bi led to the formation of strong Lewis acid sites. Epoxidation of cyclohexene was found to depend on both Bi and Na content. On 3%Bi-ZSM-5 it occurred with rather good conversion and selectivity to epoxide. No visible leaching was evidenced. The catalysts were reused for several runs.

Layered structural analogues of zinc and cadmium monophosphonates have been prepared, using rationally designed bis(phosphonic) acids, and characterized. As a consequence, the density of organic groups in the interlayer space is reduced by half.

Various resins carrying pyridine rings have been used to support ionic or neutral chromium complexes, and oxidize selectively octanol-2 into octanone-2. The best results involve macroporous resins with large pores or non cross-linked grafted polymers, provided that grafted polymers are compatible enough with the solvent medium for the reaction.

Highly porous open cell polymers materials, so-called polyHIPEs, have been prepared through the polymerization of high internal phase emulsions (HIPEs). Styren/DVB polyHIPEs were synthesized and shaped as columns or small cubes. The cell size and size distribution were also varied. The surface of this material is covered by a large number of vinylbenzene groups that allow for the bonding of small functional molecules in general and, more specially, of the stereospecific addition of thiol groups through a free radical pathway. A tin-chloride polyHIPE was also prepared using tin-chloride initial monomers in the emulsion. Functional polyHIPEs have been shown to be very efficient and selective scavengers for the extraction of certain molecules in solution. They can also be used for free radical cyclisation., Des supports polymères insolubles, à haute porosité et à cellules ouvertes, appelés polyHIPEs, ont été préparés par polymérisation d'émulsions inverses hautement concentrées (HIPEs). Un polyHIPE précurseur, le (vinyl)polystyrène polyHIPE, a été synthétisé puis caractérisé dans le but d'être fonctionnalisé sous forme de colonne ou de petits dés. Ce précurseur, porteur d'un grand nombre de groupements vinylbenzyle, permet l'addition de petites molécules fonctionnelles, en particulier l'addition régiosélective par voie radicalaire de thiols fonctionnels. Un polyHIPE stannique a également été préparé par copolymérisation de monomères chlorostanniques. Les polyHIPEs fonctionnels se sont révélés efficaces pour l'extraction sélective d'espèces chimiques en solution et pour des réductions et cyclisations radicalaires. Le contrôle de la taille et de la polydispersité des cellules a été étudié.