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Catalytic activity of Keggin heteropolycompounds in the Pechmann reaction

Paper ID Volume ID Publish Year Pages File Format Full-Text
43279 45961 2008 8 PDF Available
Title
Catalytic activity of Keggin heteropolycompounds in the Pechmann reaction
Abstract

Different heteropolycompounds were used as catalysts in the synthesis of coumarins from phenols and ethyl acetoacetate. The H3PMo12O40 and H3PW12O40 Keggin heteropolyacids were supported on different types of silica. On the other hand, the aluminium salts of these heteropolyacids and that of the H4SiW12O40 acid were prepared. The specific surface area (SBET), and the mean pore diameter of the obtained catalysts were estimated from the adsorption isotherms of nitrogen at 77 K. Their Fourier transform infrared spectra were recorded and their acidity was determined by potentiometric titration with a solution of n-butylamine in acetonitrile. The catalytic activity using several phenols such as resorcinol, 3,5-dimethoxyphenol, α-naphtol and β-naphtol were determined. High yield of product was obtained in the case of 4-methyl-7-hydroxycoumarin (80–95%), 4-methyl-5,7-dimethoxycoumarin (60–92%) and 4-methyl-7,8-benzocoumarin (90%). However, the 4-methyl-5,6-benzocoumarin yield was low. The use of microwave radiation as power source increases the reaction yield and mainly decreases the reaction time.

Graphical abstractDifferent heteropolycompounds were used as catalysts in the synthesis of coumarins from phenols and ethyl acetoacetate. Keggin heteropolyacids were supported on silica and the aluminium salts of these heteropolyacids were prepared. The catalytic activity using several phenols were determined and high yield of product was obtained in the case of 4-methyl-7-hydroxycoumarin, 4-methyl-5,7-dimethoxycoumarin and 4-methyl-7,8-benzocoumarin. The use of microwave radiation increases the reaction yield and mainly decreases the reaction time.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Catalysts; Keggin heteropolycompounds; Pechmann reaction
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Catalytic activity of Keggin heteropolycompounds in the Pechmann reaction
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 339, Issue 1, 15 April 2008, Pages 53–60
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
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Any Questions? feel free to contact us