Alkylaminophosphazenes as Efficient and Tuneable Phase‐Transfer Agents for Polyoxometalate‐Catalysed Biphasic Oxidation with Hydrogen Peroxide. Issue 1 (19th November 2015)

• Record Type: Journal Article
• Authors: Craven, Michael; Yahya, Rana; Kozhevnikova, Elena F.; Robertson, Craig M.; Steiner, Alexander; Kozhevnikov, Ivan V.
• Is Part Of: ChemCatChem. Volume 8:Issue 1(2016)
• Page Start: 200
• Page End: 208
• Publication Date: 2015-11-19
• Subjects: epoxidation -- hydrogen peroxide -- phase-transfer agents -- phosphazenes -- polyoxometalates; Catalysis -- Periodicals; 541.39505
• DOI: 10.1002/cctc.201500922
• Languages: English
• ISSNs: 1867-3880

Abstract

Abstract: Alkylaminophosphazenes (RPN) are efficient and tuneable phase‐transfer agents for environmentally benign biphasic oxidation with hydrogen peroxide catalysed by polyoxometalates (POMs). Substituent groups on the phosphazene ring can be varied to modify the phase‐transfer efficiency of RPN for use in water–organic two‐phase systems. Active phosphazene–polyoxometalate aggregates that self‐assemble in situ from RPN and Keggin POMs, such as PMo12 O40 3− and PW12 O40 3−, were found to be efficient and recyclable catalysts for the oxidation of benzothiophenes and the epoxidation of alkenes with hydrogen peroxide. Lipophilic phosphazene cations present in these aggregates render the POM soluble in organic media. Catalyst activity in the biphasic oxidation with H2 O2 varies with the RPN substituent alkylamino groups with respect to the solvent system used. The activity decreases in the series of POMs: PMo12 O40 3− >PW12 O40 3− ≫SiW12 O40 4− irrespective of the solvent system used. Abstract : Phase‐transfer phosphazenes : Substituent groups on the phosphazene ring of alkylaminophosphazenes (RPN) can be varied to modify the phase‐transfer efficiency of RPN for use in water–organic two‐phase systems. Active phosphazene–polyoxometalate (POM) aggregates that self‐assemble in situ from RPN and Keggin POMs, such as PMo12 O40 3− and PW12 O40 3−, were found to be efficient and recyclable catalysts for the oxidation of benzothiophenes and the epoxidation of alkenes with hydrogen peroxide.