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Highly efficient and selective aqueous phase hydrogenation of aryl ketones, aldehydes, furfural and levulinic acid and its ethyl ester catalyzed by phosphine oxide-decorated polymer immobilized ionic liquid-stabilized ruthenium nanoparticles

Lookup NU author(s): Dr Simon DohertyORCiD, Dr Julian Knight, Tom Backhouse, Tina Tran, Reece Paterson, Dr Hussam Alharbi

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

Impregnation of phosphine-decorated styrene-based Polymer Immobilized Ionic Liquid (PPh2-PIIL) with ruthenium (III) trichloride resulted in facile reduction of the ruthenium to afford Ru(II)‑impregnated phosphine oxide-decorated PIIL (O=PPh2PIIL). The derived phosphine oxide-decorated Polymer Immobilized Ionic Liquid-Stabilized RuNPs (RuNP@O=PPh2-PIILS) catalyse the highly efficient and selective aqueous phase reduction of the carbonyl group in aryl and heteroaryl ketones and aldehydes, including furfural, as well as the hydrogenation of levulinic acid and its ethyl ester to afford g‑valerolactone (GVL). While this is the first report of RuNPs stabilized by a phosphine oxide‑modified support, there appear to be several recent examples of similar serendipitous oxidations during the synthesis of RuNPs by impregnation of a phosphine-decorated polymer with ruthenium trichloride; as these were either misinterpreted or not recognised as such we have carried out a detailed characterization and evaluation of this system. Reassuringly, RuNP@O=PPh2-PIILS generated from phosphine oxide-decorated polymer immobilized ionic liquid (O=PPh2-PIIL) impregnated with ruthenium trichloride is as efficient as that prepared directly from RuCl3 and PPh2-PIIL. Incorporation of PEG into the polymer support improved catalyst performance and the initial TOF of 2,350 h-1 obtained for the aqueous phase hydrogenation of acetophenone is among the highest to be reported for a ruthenium nanoparticle‑based catalyst. Under optimum conditions, RuNP@O=PPh2-PEGPIILS recycled ten times with only a minor reduction in activity and no detectable change in selectivity. High yields and excellent selectivities were also obtained for hydrogenation of the C=O across a range of substituted aryl and heteroaryl ketones. Complete hydrogenation of the aromatic ring and C=O could also be achieved by increasing the pressure and temperature accordingly. The same system also catalyzes the aqueous phase hydrogenation of furfural under mild conditions with an initial TOF of 3,160 h-1 as well as the selective hydrogenation of levulinic acid and its ethyl ester to -valerolactone (GVL); reaction times for the latter could be reduced quite significantly by addition of either butyric acid or Amberlyst H-15.


Publication metadata

Author(s): Doherty S, Knight JG, Backhouse T, Tran TST, Paterson R, Stahl F, Alharbi HY, Chamberlain TW, Bourne RA, Stones R, Griffiths A, White JP, Aslam Z, Hardacre C, Daly H, Hart J, Temperton RH, O'Shea JN, Rees NH

Publication type: Article

Publication status: Published

Journal: Catalysis Science & Technology

Year: 2022

Pages: EPub ahead of Print

Online publication date: 07/04/2022

Acceptance date: 23/03/2022

Date deposited: 07/04/2022

ISSN (print): 2044-4753

ISSN (electronic): 2044-4761

Publisher: Royal Society of Chemistry

URL: https://doi.org/10.1039/D2CY00205A

DOI: 10.1039/D2CY00205A


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Funding

Funder referenceFunder name
EP/S023836/1EPSRC
EP/SO22473/1

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