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Oxyfunctionalisation of adamantane using inorganic–organic hybrid materials based on isopoly and heteropoly anions: Kinetics and mechanistic studies

Paper ID Volume ID Publish Year Pages File Format Full-Text
43373 45966 2007 10 PDF Available
Title
Oxyfunctionalisation of adamantane using inorganic–organic hybrid materials based on isopoly and heteropoly anions: Kinetics and mechanistic studies
Abstract

Oxyfunctionalisation of adamantane with 30% aq.H2O2 in butyronitrile solvent was efficiently catalyzed by inorganic–organic hybrid materials synthesized by the immobilisation of isopoly (WOx = sodium tungstate, MoOx = sodium molybdate and VOx = sodium metavanadate) and heteropoly anions (V1 = H4[PMo11VO40]·32·5H2O,and V3 = H6[PMo9V3O40]·34H2O, STA = silicotungstic acid, TPA = tungstophosphoric acid and MPA = molybdophosphoric acid) onto mesoporous silica (SBA-15). These catalysts were well characterized by standard techniques and it was found that polyoxometalate has been retained all its bulk characteristics upon immobilisation onto mesoporous silica. Among the catalysts 10-molybdo-2-vanadophosphoric acid (H5[PMo10V2O40]·32·5H2O) immobilized onto amine-functionalized SBA-15 gave the highest activity under the conditions in the liquid phase oxidation of adamantane with 30% aq.H2O2 in butyronitrile solvent and gave mainly 1-adamantanol. Kinetic parameter measurements were performed by following initial rate approach for determining the rate dependence of the reaction. In situ UV-vis and electron paramagnetic resonance (EPR) spectroscopic studies carried out showed that the vanadium (V) superoxo intermediate species formed was responsible for the CH bond activation of adamantane to give 1-adamentanol. Based on this, a plausible mechanism for the oxidation of adamantane to 1-adamantanol has been proposed. The catalysts leaching studies carried out by following a standard procedure ruled out any contribution by the active vanadium species that could leach into the reaction medium and catalysts were truly functioned as heterogeneous catalysts.

Graphical abstractOxyfunctionalisation of adamantane with 30% aq.H2O2 in butyronitrile solvent was efficiently catalyzed by isopoly and heteropoly anions immobilized onto mesoporous silica (SBA-15) and 10-molybdo-2-vanadophosphoric acid (H5[PMo10V2O40]·32·5H2O)–SBA-15 gave highest activity to give mainly 1-adamantanol. Vanadium (V) superoxo intermediate species formed was responsible for the CH bond activation of adamantane to give 1-adamentanol. Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Inorganic–organic hybrid materials; Oxyfunctionalisation; Adamantane; Vanadium (V) superoxo intermediate
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Oxyfunctionalisation of adamantane using inorganic–organic hybrid materials based on isopoly and heteropoly anions: Kinetics and mechanistic studies
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 333, Issue 1, 3 December 2007, Pages 143–152
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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