PALERMO, V. et al. A Hybrid System Base on Silica-Alumina and Keggin Heteropolyacid as Catalyst in the Suitable 2-(2-Furyl)-Chromones. []. , 13, 1, pp.93-102.   26--2023. ISSN 0121-7488.  https://doi.org/10.19053/01217488.v13.n1.2022.14165.

Molybdophosphoric acid/silica-alumina composites were synthesized through a process, in which the heteropolyacid was impregnated on different silica-aluminas, obtained by sol-gel. Three different techniques were used to prepare the samples. The catalysts were prepared by incipient wetness impregnation and different thermal treatments were applied. The hybrid systems were characterized by S BET , XRD, and acidity measurements.

The catalytic activity of these materials was tested in the solvent-free cyclization of 1-(2-hydroxyphenyl)-3-(2-furyl)-1,3-propanedione to 2-(2-furyl)-chromones. The transformation gives very good yields of product, free of secondary products. Environmental benign procedure, and easy catalyst separation, is relevant features of this methodology. In this way, the catalyst can be used and reused six cycles without loss of catalytic activity. The most active catalyst was also used in the solvent-free cyclization of 1-(2-hydroxyphenyl)-3-(2-furyl)-2-propen-1-one and the methodology can be extended to the synthesis of other 2-(2-(furyl)-chromones and chromanones. The green context for this new procedure was confirmed by greenmetrics parameters.

: Keggin heteropolyacids; Silica-alumina; Sol-gel synthesis; 2-(2-Furyl)-chromones; 2-(2-Furyl)-chromanones.

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