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Supported trifluoromethanesulfonic acid as catalyst in the synthesis of flavone and chromone derivatives

Paper ID Volume ID Publish Year Pages File Format Full-Text
44378 46020 2007 7 PDF Available
Title
Supported trifluoromethanesulfonic acid as catalyst in the synthesis of flavone and chromone derivatives
Abstract

Solid acid catalysts based on trifluoromethanesulfonic acid (triflic acid, TFMS) were synthesized using titania with different textural properties as support, obtained by increasing the calcination temperature (Ti100, Ti200, Ti300, and Ti400). They were characterized by FT-IR, DTA-TGA, and BET. The acidic characteristics of the catalysts were determined by potentiometric titration with n-butylamine. According to this technique, the catalysts present very strong acid sites. Their acid strength decreases slightly in the order Ti100 > Ti200 > Ti300 > Ti400, as a result of the partial dehydroxylation that takes place during the thermal treatment of the supports.The amount of trifluoromethanesulfonic acid firmly adsorbed on the support depends on the number of –OH groups available on the titania to be protonated, which decreases with the increase in the calcination temperature.The new catalysts were tested in the cyclization of 1-(2-hydroxyphenyl)-3-phenyl-1,3-propanedione. The reaction experiments were performed using toluene as the solvent at reflux. In all cases, the product (flavone) was obtained with high selectivity. The activity of the catalysts is dependent on the textural properties of the support used to obtain the catalysts and the amount of triflic acid firmly adsorbed on it. The same reaction conditions were applied to the preparation of eight substituted flavones and chromones. Conversions up to 88% were obtained using the Ti100 supported TFMS catalyst.

Graphical abstractSolid acid catalysts based on trifluoromethanesulfonic acid (triflic acid, TFMS) were synthesized using titania with different textural properties as support, obtained by increasing the calcination temperature. They were characterized by FT-IR, DTA-TGA, and BET. The acidic characteristics of the catalysts were determined by potentiometric titration with n-butylamine.The new catalysts were tested in the cyclization of 1-(2-hydroxyphenyl)-3-phenyl-1,3-propanedione. In all cases, the product (flavone) was obtained with high selectivity. The activity of the catalysts is dependent on the textural properties of the support used to obtain the catalysts and the amount of triflic acid firmly adsorbed on it.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Supported trifluoromethanesulfonic acid; Supported triflic acid; Flavones; Chromones; Titania
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Supported trifluoromethanesulfonic acid as catalyst in the synthesis of flavone and chromone derivatives
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 324, 17 May 2007, Pages 62–68
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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Price was $35.95
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Price after discount Only $4.95
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