[Ru(triphos)(CH3CN)3](OTf)2 as a homogeneous catalyst for the hydrogenation of biomass derived 2,5-hexanedione and 2,5-dimethyl-furan in aqueous acidic mediumElectronic supplementary information (ESI) available: Compound data sheets and spectra for complexes 1 and 2. GC methods and representative traces and retention times. Images of high-pressure hydrogenation reactor set-up. Live spreadsheets for the calculation of H2(g) solubility in xlsx and ods formats. CCDC 1535963 (1) and 1527925 (2). For

• Main Authors: Latifi, Elnaz, Marchese, Austin D, Hulls, Margaret C. W, Soldatov, Dmitriy V, Schlaf, Marcel
• Format: Article
• Language: English
• ISSN: 1463-9262; 1463-9270
• DOI: 10.1039/c7gc01956d

The complex [Ru(triphos)(CH 3 CN) 3 ](OTf) 2 is an effective catalyst for the hydrogenation of 2,5-hexanedione and 2,5-dimethyl-furan in aqueous acidic medium at temperatures between 150 and 200 °C realizing up to 96% combined yields of 2,5-hexanediol and 2,5-dimethyl-tetrahydrofuran with the product distribution being sensitive to the amount of acid co-catalyst (HOTf) present. For the furan, the reaction pathway is through an acid-catalyzed hydrolysis to the dione rather than direct hydrogenation of the ring. The hydrogenation of the dione shows a first order dependence on hydrogen pressure as determined by direct hydrogen uptake rate measurements at temperature and pressure (1.38-6.90 MPa at 150 °C) and is postulated to operate through a heterolytic activation of hydrogen gas by [Ru(H) x (triphos)(Y) y ] n + (Y = solvent, water, counter ion) species formed in situ by loss and hydrogenation of the nitrile ligands. In water the catalyst is deactivated by dimerization to [Ru 2 (μ-OH) 3 (triphos) 2 ](OTf). In aqueous acidic medium a direct hydrogenation of 2,5-dimethylfuran does not take place with the homogeneous [Ru(triphos)]-system opening a pathway to the more valuable 2,5-hexanediol.