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New extraction procedure for protonated polyoxometalates prepared in aqueous-organic solution and characterisation of their catalytic ability

Paper ID Volume ID Publish Year Pages File Format Full-Text
39566 45827 2014 7 PDF Available
Title
New extraction procedure for protonated polyoxometalates prepared in aqueous-organic solution and characterisation of their catalytic ability
Abstract

•Appropriate procedure was developed for isolation of protonated polyoxometalates (POMs).•The protonated POMs were characterised with elemental analysis and spectroscopy.•The acidity of the protonated POMs were measured using a Hammett indicator.•The catalytic ability of protonated POMs were investigated in four organic syntheses.

Although POMs prepared in aqueous-organic solutions have been reported to exhibit interesting chemical properties and may be efficient catalysts, they could not be isolated in their protonated form using the normal extraction method. In this study, a new procedure of isolating protonated POMs, [S2VxM18−xO62](4+x)− and [AsVxM12−xO40](3+x)− (M = Mo, W; x = 0–2), which were prepared in an aqueous-organic mixed solution, was developed by modifying and optimising the extraction conditions. Isolated protonated POMs were characterised using IR and Raman spectroscopy, and their acidity was measured using a Hammett indicator. The acidity of H4S2W18O62, H5S2VW17O62, H4S2Mo18O62, and H3As2W18O62 was stronger than that of H3PW12O40. Their catalytic ability was investigated in multiple types of organic reactions, including pinacol rearrangement, acetal formation with benzaldehyde and ethylene glycol, and the Friedel-Crafts acylation of anisole with ethyl pyruvate. They exhibited greater catalytic ability than commercially available POMs such as H3PM12O40 and H4SiM12O40 (M = Mo, W).

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Keywords
Polyoxometalate; Extraction; Acidity; Strong acid; Catalysis
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New extraction procedure for protonated polyoxometalates prepared in aqueous-organic solution and characterisation of their catalytic ability
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 485, 5 September 2014, Pages 181–187
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
Online Support
Any Questions? feel free to contact us