María Teresa Navarro

Lewis acidic Sn(IV) centers—grafted onto MCM-41—as catalytic sites for the Baeyer–Villiger oxidation with hydrogen peroxide

Sn(IV) centers have been grafted onto mesoporous MCM-41 using different RnSnX4−n precursors. For a successful incorporation of the tin, one or two alkyl substituents are beneficial. The calcined samples are able to activate a carbonyl bond for nucleophilic attack as it could be shown by in situ IR spectroscopy. The resulting catalysts are active for the Baeyer–Villiger oxidation of various substrates with hydrogen peroxide and achieve good conversions and selectivities. Chemoselective oxidations toward unsaturated lactones are obtained from unsaturated ketones. The Lewis acidity and the catalytic performance of the grafted Sn(IV) centers are very similar to the directly synthesized Sn-MCM-41, but lower than those of the Sn-Beta zeolite.

Synthesis of an ultralarge pore titanium silicate isomorphous to MCM-41 and its application as a catalyst for selective oxidation of hydrocarbons

An ultralarge pore titanium silicate with MCM-41 structure has been prepared by direct hydrothermal synthesis; this material gives rise to useful catalysts for the selective oxidation of small and large organic compounds.

Modular Organic Structure-Directing Agents for the Synthesis of Zeolites

Routes to Rare Zeolites Zeolites are microporous crystalline solids with well-defined structures. Although many naturally occurring ones have been obtained in laboratory synthesis, some have remained elusive. One of these, boggsite, is of interest for catalytic reactions because it has large channels defined by rings of 10 or 12 atoms that intersect within its crystalline lattice. Simancas et al. (p. 1219) report the synthesis of boggsite by using phosphazenes as the organic groups that directed the formation of rings during synthesis. These reagents can be readily modified—a feature that should allow greater flexibility in synthesis routes. Phosphazene molecules enable the synthesis of a rare naturally occurring zeolite. Organic structure-directing agents (OSDAs) are used to guide the formation of particular types of pores and channels during the synthesis of zeolites. We report that the use of highly versatile OSDAs based on phosphazenes has been successfully introduced for the synthesis of zeolites. This approach has made possible the synthesis of the elusive boggsite zeolite, which is formed by 10- and 12-ring intersecting channels. This topology and these pore dimensions present interesting opportunities for catalysis in reactions of industrial relevance.

On the shape selective acylation of 2-methoxynaphthalene over polymorph C of Beta (ITQ-17)

Abstract 2-Methoxynaphthalene (2-MN) has been acylated with acetic anhydride on polymorph C of Beta (ITQ-17), and 2-acetylmethoxynaphthalene (2-AMN) and 1-acetylmethoxynaphthalene (1-AMN) have been obtained. The diffusivity of the two isomer products, as determined by molecular dynamics, shows that the ratio of the diffusion coefficients for 2-AMN/1-AMN is one order of magnitude larger for polymorph C than for polymorphs A and B (Beta zeolite). This corresponds very well with experimental acylation results that show a higher selectivity for 2-AMN on polymorph C when reaction is carried out in batch as well as in a fixed-bed continuous reactor.

ONE STEP SYNTHESIS OF HIGHLY ACTIVE AND SELECTIVE EPOXIDATION CATALYSTS FORMED BY ORGANIC-INORGANIC TI CONTAINING MESOPOROUS COMPOSITES

Ti-MCM-41 materials with methylated silicons have been prepared in one step synthesis; the resultant organic–inorganic composites are highly stable and present the highest activity and selectivity ever reported on Ti containing mesoporous catalysts for the epoxidation of olefins using organic peroxides.

Incorporating a Temporal Bounded Execution to the CBR Methodology

In real-time Multi-Agent Systems, Real-Time Agents merge intelligent deliberative techniques with real-time reactive actions in a distributed environment. CBR has been successfully applied in Multi-Agent Systems as deliberative mechanism for agents. However, in the case of Real-Time Multi-Agent Systems the temporal restrictions of their Real-Time Agents make their deliberation process to be temporally bounded. Therefore, this paper presents a guide to temporally bound the CBR to adapt it to be used as deliberative mechanism for Real-Time Agents.