Dehydration of fructose to HMF in presence of (H3O)xSbxTe(2-x)O6 (x = 1, 1.1, 1.25) in H2O-MIBK

The pyrochlores (H 3 O) x Sb x Te (2-x) O 6 (x = 1, 1.1 and 1.25) obtained by ion exchange from K x Sb x Te (2-x) O 6 oxides were used as catalysts for the conversion of fructose to 5-hydroxymethylfurfural (HMF) in H 2 O/Methyl isobutyl ketone (MIBK). The structure of the resulting compounds as well as the location of the H 3 O + units inside the three-dimensional network, were determined by XRD from powder samples. The effect of factors such as reaction time and temperature on the formation of HMF was studied. A fructose conversion of 99% and a yield of 59% were achieved after 120 min of reaction time and at 150 °C temperature. The percentage of substitution of the cations Sb and Te in the position B of the pyrochlore was determinant to achieve the maximum incorporation of H 3 O + ions in the pyrochlore structure, which allowed to correlate the density of acidic sites present in the materials and their catalytic activity.Fil: Mayer, Sergio Federico. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Investigación en Nanociencia y Nanotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Falcon, Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Tecnológica Nacional. Facultad Regional Córdoba. Centro de Inv. y Tecnología Química. Grupo Fisicoquímica de Nuevos Materiales; ArgentinaFil: Di Paola Naranjo, Romina Daniela. Universidad Nacional de Córdoba. Secretaría de Ciencia y Tecnología. Instituto Superior de Investigación, Desarrollo y Servicio de Alimentos; ArgentinaFil: Ribota, Pablo Daniel. Universidad Nacional de Córdoba. Secretaría de Ciencia y Tecnología. Instituto Superior de Investigación, Desarrollo y Servicio de Alimentos; ArgentinaFil: Moyano, Elizabeth Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Morales-delaRosa, S.. Consejo Superior de Investigaciones Científicas. Instituto de Catálisis y Petroleoquímica. Grupo de Energía y Química Sostenibles; EspañaFil: Mariscal, R.. Consejo Superior de Investigaciones Científicas. Instituto de Catálisis y Petroleoquímica. Grupo de Energía y Química Sostenibles; EspañaFil: Campos-Martín, J. M.. Consejo Superior de Investigaciones Científicas. Instituto de Catálisis y Petroleoquímica. Grupo de Energía y Química Sostenibles; EspañaFil: Alonso, J. A.. Consejo Superior de Investigaciones Científicas. Instituto de Ciencia de Materiales de Madrid; EspañaFil: Fierro, J. L. G.. Consejo Superior de Investigaciones Científicas. Instituto de Catálisis y Petroleoquímica. Grupo de Energía y Química Sostenibles; Españ

CATALYTIC EPOXIDATION OF CYCLOHEXENE WITH TERT-BUTYLHYDROPEROXIDE USING AN IMMOBILIZED MOLYBDENUM CATALYST

This work describes the synthesis of molybdenum complexes immobilized on a silica support and their performance in the epoxidation reaction of cyclohexene using tert-butylhydroperoxide (TBHP) as the oxidizing agent. The catalyst synthesis included solubilization of variable amounts of bis-oxomolybdenum (VI) acetylacetonate precursor in different solvents such as tetrahydrofuran (THF), ethanol, THF/water and ethanol/water mixtures and contact with the silica support. Characterization techniques demonstrated that the nature of the incorporated molybdenum species depends markedly on the solvent employed. If the solvent employed is an ethanol:water mixture, physical adsorption of the Mo-species onto the support surface occurs; however, when THF is used as the solvent (THF catalyst series), molybdenum is grafted on the silica surface via chemical bonding with the surface hydroxyl groups of silica. Specifically, these latter catalysts show similar performance to that of the homogeneous catalyst, although long-term experiments showed deactivation by leaching of the active phase.Peer reviewe

CAG repeat expansion in Huntington disease determines age at onset in a fully dominant fashion

Objective: Age at onset of diagnostic motor manifestations in Huntington disease (HD) is strongly correlated with an expanded CAG trinucleotide repeat. The length of the normal CAG repeat allele has been reported also to influence age at onset, in interaction with the expanded allele. Due to profound implications for disease mechanism and modification, we tested whether the normal allele, interaction between the expanded and normal alleles, or presence of a second expanded allele affects age at onset of HD motor signs. Methods: We modeled natural log-transformed age at onset as a function of CAG repeat lengths of expanded and normal alleles and their interaction by linear regression. Results: An apparently significant effect of interaction on age at motor onset among 4,068 subjects was dependent on a single outlier data point. A rigorous statistical analysis with a wellbehaved dataset that conformed to the fundamental assumptions of linear regression (e.g., constant variance and normally distributed error) revealed significance only for the expanded CAG repeat, with no effect of the normal CAG repeat. Ten subjects with 2 expanded alleles showed an age at motor onset consistent with the length of the larger expanded allele. Conclusions: Normal allele CAG length, interaction between expanded and normal alleles, and presence of a second expanded allele do not influence age at onset of motor manifestations, indicating that the rate of HD pathogenesis leading to motor diagnosis is determined by a completely dominant action of the longest expanded allele and as yet unidentified genetic or environmental factors. Copyright © 2012 by AAN Enterprises, Inc