Silicagel-supported H6P2W18O 62.24H2O: A reusable catalyst to prepare diphenylmethyl (DPM) ethers

In this work, we report an efficient and facile preparation of diphenylmethylethers (benzydryl ethers, DPM-ethers) from benzhydrol and alcohols or phenols. Wells-Dawson heteropolyacid (H6P2W 18O62.24H2O), bulk or supported on silica showed catalytic activity for DPM-ethers preparation in toluene, at 60-80°C, in 0.5-1.5h. In these conditions twelve diphenylmethylethers of alcohols and phenol were obtained which excellent yields (78-96%). The heterogeneous reaction conditions provided a very simple, environmentally friendly, clean, economical and selective protocol, for the preparation of unsymmetrical ethers. The catalyst is easily recycled and reused without loss of the catalytic activity.Facultad de Ciencias Agrarias y ForestalesCentro de Investigación y Desarrollo en Ciencias Aplicada

Synthesis of substituted flavones and chromones using a Wells-Dawson heteropolyacid as catalyst

In this work, we report the use of bulk and silica-supported Wells-Dawson acid (H2P2W18O62.24H2O) as reusable, heterogeneous catalysts to obtain substituted flavones and chromones for the cyclization of 1-(2-hydroxyphenyl)-3-aryl-1,3-propanediones. The reaction experiments were performed using toluene as solvent at reflux and in the absence of solvent, at 110°C. Under these conditions eleven examples were obtained with very good yields (82-91%) and high selectivity. The catalysts were easily recycled and reused without loss of their catalytic activity. The presented synthetic method is a simple, clean and environmentally friendly alternative for synthesizing substituted flavones and chromones.Centro de Investigación y Desarrollo en Ciencias AplicadasFacultad de Ciencias Agrarias y ForestalesLaboratorio de Servicios a la Industria y al Sistema Científic

Efficient deprotection of phenol methoxymethyl ethers using a solid acid catalyst with Wells-Dawson structure

Deprotection of various phenols from their respective methoxymethyl ethers using an heteropolyacid catalyst was studied. The catalyst was the Wells-Dawson heteropolyacid, used both in bulk or supported on silica. Yields were high to quantitative after less than one hour reaction time and the catalyst was easily recoverable and reusable.Facultad de Ciencias Exacta

Synthesis of substituted flavones and chromones using a Wells-Dawson heteropolyacid as catalyst

In this work, we report the use of bulk and silica-supported Wells-Dawson acid (H2P2W18O62.24H2O) as reusable, heterogeneous catalysts to obtain substituted flavones and chromones for the cyclization of 1-(2-hydroxyphenyl)-3-aryl-1,3-propanediones. The reaction experiments were performed using toluene as solvent at reflux and in the absence of solvent, at 110°C. Under these conditions eleven examples were obtained with very good yields (82-91%) and high selectivity. The catalysts were easily recycled and reused without loss of their catalytic activity. The presented synthetic method is a simple, clean and environmentally friendly alternative for synthesizing substituted flavones and chromones.Centro de Investigación y Desarrollo en Ciencias AplicadasFacultad de Ciencias Agrarias y ForestalesLaboratorio de Servicios a la Industria y al Sistema Científic

Direct esterification of cinnamic acids with phenols and imidoalcohols: a simple, heteropolyacid-catalyzed procedure

A convenient procedure for the direct esterification of cinnamic acids with phenols or 2-(N-phthalimido) ethanol is described. The method is simple and clean, environmentally friendly and high-yielding for both electron-releasing and electron-withdrawing substituted phenols. The heteropolyacid H 6P2W18O62·24 H2O was employed as catalyst, both bulk and supported on silica. No stoichiometric activation of the carboxyl group or condensing reagents is necessary. The effects of temperature, reaction time, amount of the catalyst used and mole ratio of the reactants on the ester yield were checked. Suitable conditions for the reaction include a 1:1 molar ratio of reactants and a 1 mmol % mass ratio of catalyst to reactant. Eighteen aryl and phthalimidoethyl cinnamates were obtained, yields ranged in 84-95% for most of the esters. The catalyst shown to be reusable for at least three times without occurring an appreciable loss of its activity.Facultad de Ciencias Agrarias y ForestalesCentro de Investigación y Desarrollo en Ciencias Aplicada

Direct esterification of cinnamic acids with phenols and imidoalcohols: a simple, heteropolyacid-catalyzed procedure

A convenient procedure for the direct esterification of cinnamic acids with phenols or 2-(N-phthalimido) ethanol is described. The method is simple and clean, environmentally friendly and high-yielding for both electron-releasing and electron-withdrawing substituted phenols. The heteropolyacid H 6P2W18O62·24 H2O was employed as catalyst, both bulk and supported on silica. No stoichiometric activation of the carboxyl group or condensing reagents is necessary. The effects of temperature, reaction time, amount of the catalyst used and mole ratio of the reactants on the ester yield were checked. Suitable conditions for the reaction include a 1:1 molar ratio of reactants and a 1 mmol % mass ratio of catalyst to reactant. Eighteen aryl and phthalimidoethyl cinnamates were obtained, yields ranged in 84-95% for most of the esters. The catalyst shown to be reusable for at least three times without occurring an appreciable loss of its activity.Facultad de Ciencias Agrarias y ForestalesCentro de Investigación y Desarrollo en Ciencias Aplicada

Silicagel-supported H6P2W18O 62.24H2O: A reusable catalyst to prepare diphenylmethyl (DPM) ethers

In this work, we report an efficient and facile preparation of diphenylmethylethers (benzydryl ethers, DPM-ethers) from benzhydrol and alcohols or phenols. Wells-Dawson heteropolyacid (H6P2W 18O62.24H2O), bulk or supported on silica showed catalytic activity for DPM-ethers preparation in toluene, at 60-80°C, in 0.5-1.5h. In these conditions twelve diphenylmethylethers of alcohols and phenol were obtained which excellent yields (78-96%). The heterogeneous reaction conditions provided a very simple, environmentally friendly, clean, economical and selective protocol, for the preparation of unsymmetrical ethers. The catalyst is easily recycled and reused without loss of the catalytic activity.Facultad de Ciencias Agrarias y ForestalesCentro de Investigación y Desarrollo en Ciencias Aplicada

Ce-Mn mixed oxides as supports of copper- and nickel-based catalysts for water-gas shift reaction

Cerium-manganese mixed oxides with different composition were prepared by co-precipitation, characterized and evaluated for the water–gas shift (WGS) reaction. Base metal (5 wt.% Cu and 5 wt.% Ni) catalysts supported on Ce–Mn mixed oxides were also tested for the WGS reaction. The activity of the bare supports is higher in the mixed samples than in pure ceria or manganese oxide. This result can be explained by a combination of greater reducibility and surface area in the mixed samples. Addition of base metals produces superior WGS catalysts. Particularly, nickel catalysts tested are able to reduce typical CO concentrations entering the WGS process to the CO levels tolerated by phosphoric acid fuel cells in a single unit operated at 400 °C.Centro de Investigación y Desarrollo en Ciencias AplicadasUniversidad de Buenos Aire

Hacia la producción sustentable de moléculas con potencial actividad biológica : Síntesis de piridinas con sólidos reciclables mediante tecnologías limpias

La sociedad moderna actual cuenta con innumerables productos que surgen como resultado de procesos de síntesis química. En este contexto, nuestra calidad de vida es fuertemente dependiente del consumo de productos farmacéuticos, tales como antibióticos, analgésicos, o antiinflamatorios. La industria farmacéutica logró un gran desarrollo en épocas donde se desconocía la potencialidad tóxica de algunos reactivos y solventes empleados, descuidándose también el tratamiento y depósito de residuos generados. Estos aspectos, junto con otros factores, han logrado que el desarrollo de la industria sea acompañado por una percepción negativa de la población en general.Universidad Nacional de La Plat

Hacia la producción sustentable de moléculas con potencial actividad biológica : Síntesis de piridinas con sólidos reciclables mediante tecnologías limpias

La sociedad moderna actual cuenta con innumerables productos que surgen como resultado de procesos de síntesis química. En este contexto, nuestra calidad de vida es fuertemente dependiente del consumo de productos farmacéuticos, tales como antibióticos, analgésicos, o antiinflamatorios. La industria farmacéutica logró un gran desarrollo en épocas donde se desconocía la potencialidad tóxica de algunos reactivos y solventes empleados, descuidándose también el tratamiento y depósito de residuos generados. Estos aspectos, junto con otros factores, han logrado que el desarrollo de la industria sea acompañado por una percepción negativa de la población en general.Universidad Nacional de La Plat