Phenol tetrahydropyranylation catalyzed by silica-alumina supported heteropolyacids with Keggin structure

Romanelli, Gustavo Pablo; Vázquez, Patricia; Pizzio, Luis R.; Quaranta, N.; Autino, Juan Carlos; Blanco, Mirta N.; Cáceres, Carmen Victoria

doi:10.1016/j.apcata.2003.10.043

Cited by 44 publications

(43 citation statements)

References 19 publications

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“…Figure 2 shows the optical absorption spectra obtained for the various supported HPW catalysts studied here. Large absorption features are observed in the 200-500 nm region of the spectra that are normally assigned to oxygen to metal charge transfer bands within the Keggin structure [30]. These broad bands can be deconvoluted into two individual features: a relatively narrow band at 215 and a broader band from 250 to 390 nm.…”

Section: Leaching With Watermentioning

confidence: 98%

Effects of Novel Supports on the Physical and Catalytic Properties of Tungstophosphoric Acid for Alcohol Dehydration Reactions

Herrera

Kwak

et al. 2008

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The catalytic behavior of tungstophosphoric acid supported on modified mesoporous silica materials for the dehydration of 2-butanol and methanol was studied. Specifically, the supports evaluated here consisted of unmodified MCM-41 and SBA-15 mesoporous silicas, and these materials coated with sub-monolayer quantities of alumina, titania, and zirconia. UV-Vis DRS and 31 P-NMR spectroscopy showed that the tungstophosphoric acid species retained their chemical identity in the synthesized supported form, although the spectra were influenced by the specific support material used. In addition, their acidic properties were evaluated using temperature-programmed oxidation of isopropyl amine. The differences in reaction rates between the samples reflect both the diversity in the amount of Brønsted acidic sites available for catalysis and dissimilarities in coking resistance. These two characteristics depend, in turn, on the type of support modifier used to prepare the catalyst.

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Section: Leaching With Watermentioning

confidence: 98%

Effects of Novel Supports on the Physical and Catalytic Properties of Tungstophosphoric Acid for Alcohol Dehydration Reactions

Herrera

Kwak

et al. 2008

Top Catal

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“…Para interpretar los resultados, el potencial de electrodo (EI) indica la fuerza ácida máxima de los sitios superficiales y los valores (meq/g sólido), donde se alcanza el plateau, indica el número total de sitios ácidos. La fuerza ácida de los sitios superficiales puede clasificarse de acuerdo a los siguientes rangos: sitio muy fuerte, EI> 100 mV; sitio fuerte, 0 < EI < 100 mV; sitio débil, -100 < EI< 0 mV; y sitio muy débil, EI< -100 mV [21]. En tal sentido presentaron una mayor acidez los sólidos cuyo precursor fue el MTMS y se observó en general un descenso de la misma al agregar ambos metales.…”

Section: Figura 1: Fotografías Digitales De Las Muestras Sintetizadasunclassified

Síntesis verde y caracterización de sólidos de matriz silícea con cobre y plata obtenidos a partir de dos precursores para su aplicación como aditivos antifúngicos

Arreche¹,

Igal²,

Bellotti

et al. 2015

Matéria (Rio J.)

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RESUMENLa síntesis de nuevos productos con actividad antimicrobiana, amigables con el medio ambiente, aplicados a la formulación de recubrimientos que prevengan la formación de biopelículas es un tema que ha cobrado gran relevancia en los últimos años. Las biopelículas producen cambios indeseables (biodeterioro) en las propiedades de los materiales como consecuencia de la actividad vital de los microorganismos. Por otro lado, afectan la salud humana, al constituirse en el interior de las viviendas y disminuir la calidad del aire por contribuir con la formación de bioaerosoles. El presente trabajo tiene como objetivo la síntesis verde y la caracterización de sólidos de matriz silícea asociados con cobre y plata, como contracationes de un heteropoliácido para su uso como aditivos antimicrobianos en pinturas. Los sólidos se obtienen a partir del método sol-gel mediante diferentes medios ácidos. La actividad antifúngica de los sólidos sintetizados se evaluó frente a dos aislamientos fúngicos, Alternaria alternata y Chaetomium globosum, obtenidos a partir de películas de pinturas biodeterioradas. Se prepararon sílices empleando tetraetilortosilicato y metiltrimetoxisilano como precursores y catalizadores ácidos para la reacción de hidrólisis del alcóxido. Una vez finalizada la etapa de síntesis y caracterización de las sílices propuestas, se evaluó su actividad antifúngica frente a los hongos de interés y se determinó el porcentaje de inhibición en cada caso. De los sólidos ensayados, la mayoría mostraron tener actividad antifúngica por inhibir el crecimiento de ambos hongos con las menores concentraciones en relación a su blanco, aunque los que contenían cobre y plata presentaron un mayor grado de inhibición en todos los casos.Palabras clave: biodeterioro, pinturas higiénicas, sílice, cobre, plata, método sol-gel, aditivos antimicrobianos. ABSTRACTThe synthesis of new environmentally friendly products with antimicrobial activity, applied to the formulation of coatings that prevent biofilm formation is an issue that has become important in recent years. Biofilms produce undesirable changes (biodeterioration) in material properties due to the vital activity of microorganisms. They reduce indoor air quality by contributing to the formation of bioaerosols and therefore affect human health. This paper aims to green synthesis and characterization of solid silica matrix associated with copper and silver, as counter cations of a heteropolyacid for use as antimicrobial additives in paints. The solids were obtained from the sol-gel method using different acidic medium. The antifungal activity of the synthesized solids was evaluated against two fungal isolates, Alternaria alternata and Chaetomium globosum, obtained from biodeteriorated paints films. Different silicas were prepared using tetraethyl orthosilicate and methyltrimethoxysilane as precursors and acids as catalysts for the hydrolysis reaction of the alkoxide. Once the synthesis phase and the characterization of the samples were finished, the antifungal activity agains...

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“…The measurement of the catalyst acidity by potentiometric titration with n-butylamine evaluates the total number of acid sites and their acidic strength [14]. The titration curves obtained for the catalysts are presented in Fig.…”

Section: Catalyst Characterizationmentioning

confidence: 99%

“…The same HPA supported on silica-alumina are efficient catalysts for the tetrahydro-pyranylation of phenols, a useful method in organic synthesis for the protection of hydroxyl groups [14].…”

Section: Introductionmentioning

confidence: 99%

Keggin heteropolyacid-based catalysts for the preparation of substituted ethyl β-arylaminocrotonates, intermediates in the synthesis of 4-quinolones

Pizzio

Romanelli

Vázquez

et al. 2006

Applied Catalysis A: General

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Phenol tetrahydropyranylation catalyzed by silica-alumina supported heteropolyacids with Keggin structure

Cited by 44 publications

References 19 publications

Effects of Novel Supports on the Physical and Catalytic Properties of Tungstophosphoric Acid for Alcohol Dehydration Reactions

Effects of Novel Supports on the Physical and Catalytic Properties of Tungstophosphoric Acid for Alcohol Dehydration Reactions

Síntesis verde y caracterización de sólidos de matriz silícea con cobre y plata obtenidos a partir de dos precursores para su aplicación como aditivos antifúngicos

Keggin heteropolyacid-based catalysts for the preparation of substituted ethyl β-arylaminocrotonates, intermediates in the synthesis of 4-quinolones

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