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Facile condensation of indole with benzaldehyde over Keggin-type heteropoly compounds: An initial effort toward catalyst design

Paper ID Volume ID Publish Year Pages File Format Full-Text
42577 45931 2009 5 PDF Available
Title
Facile condensation of indole with benzaldehyde over Keggin-type heteropoly compounds: An initial effort toward catalyst design
Abstract

A series of catalysts derived from Keggin-type heteropoly compounds (HPCs) were prepared and used as catalysts for the reaction of indole with benzaldehyde to afford bis(3-indolyl)phenylmethane. The results showed that the difference in catalytic activity of HPCs in this reaction depends on the number of introduced vanadium atoms in H3+nPMo12−nVnO40, kind of support, cesium content in CsxH3−xPW12O40 and nature of the metal cation in [(n-C4H9)4N](7−n)PMo2W9(Mn+·H2O)O39. The product yield was strongly dependent on the acidic characteristics which, in turn, depend on chemical composition of catalysts. In the presence of H3+nPMo12−nVnO40 and CsxH3−xPW12O40, the catalytic activity and acidity decreased with increasing V atom or cesium content. Among supported H3+nPMo12−nVnO40, H5PMo10V2O40/γ-Al2O3 is a weaker catalyst than bulk one. [(n-C4H9)4N](7−n)PMo2W9(Mn+·H2O)O39 catalysts exhibit a high electron-acceptor character and interesting structural and coordination properties. Catalytic activity of these compounds is related to the difference in their ability to coordinate substrates.

Graphical abstractCatalytic performances of different Keggin-type heteropoly compounds were investigated in the reaction of indole with benzaldehyde in solventless system. The activity of these catalysts depends on the number of introduced vanadium atoms in H3+nPMo12−nVnO40, cesium content in CsxH3−xPW12O40 and nature of the metal cation in metal substituted polyoxometalates and used support.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Keggin heteropoly compounds; Vanadomolybdophosphoric acids; Cesium Keggin salts; Metal substituted POMs; Acidity
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Facile condensation of indole with benzaldehyde over Keggin-type heteropoly compounds: An initial effort toward catalyst design
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 365, Issue 2, 31 August 2009, Pages 287–291
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
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Full-text PDF Download
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Any Questions? feel free to contact us