Acid‐, Water‐ and High‐Temperature‐Stable Ruthenium Complexes for the Total Catalytic Deoxygenation of Glycerol to Propane |
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| Authors: | Deeb Taher Prof. Dr. Michelle E. Thibault Domenico Di Mondo Michael Jennings Marcel Schlaf Prof. |
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| Affiliation: | 1. Chemistry Department, Tafila Technical University, P. O. Box: 179, Tafila 66110 (Jordan);2. The Guelph‐Waterloo Centre for Graduate Work in Chemistry (GWC)2, Department of Chemistry, University of Guelph, Guelph, Ontario, N1G 2W1 (Canada);3. Chemistry Department, University of Western Ontario, London, Ontario, Canada, N6?A 5B7 (UK) |
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| Abstract: | The ruthenium aqua complexes [Ru(H2O)2(bipy)2](OTf)2, [cis‐Ru(6,6′‐Cl2‐bipy)2(OH2)2](OTf)2, [Ru(H2O)2(phen)2](OTf)2, [Ru(H2O)3(2,2′:6′,2′′‐terpy)](OTf)2 and [Ru(H2O)3(Phterpy)](OTf)2 (bipy=2,2′‐bipyridine; OTf?=triflate; phen=phenanthroline; terpy= terpyridine; Phterpy=4′‐phenyl‐2,2′:6′,2′′‐terpyridine) are water‐ and acid‐stable catalysts for the hydrogenation of aldehydes and ketones in sulfolane solution. In the presence of HOS(O)2CF3 (triflic acid) as a dehydration co‐catalyst they directly convert 1,2‐hexanediol to n‐hexanol and hexane. The terpyridine complexes are stable and active as catalysts at temperatures ≥250 °C and in either aqueous sulfolane solution or pure water convert glycerol into n‐propanol and ultimately propane as the final reaction product in up to quantitative yield. For the terpy complexes the active catalyst is postulated to be a carbonyl species [(4′‐R‐2,2′:6′,2′′‐terpy)Ru(CO)(H2O)2](OTf)2 (R=H, Ph) formed by the decarbonylation of aldehydes (hexanal for 1,2‐hexanediol and 3‐hydroxypropanal for glycerol) generated in the reaction mixture through acid‐catalyzed dehydration. The structure of the dimeric complex [{(4′‐phenyl‐2,2′:6′,2′′‐terpy)Ru(CO)}2(μ‐OCH3)2](OTf)2 has been determined by single crystal X‐ray crystallography (Space group P (a=8.2532(17); b=12.858(3); c=14.363(3) Å; α=64.38(3); β=77.26(3); γ = 87.12(3)°, R=4.36 %). |
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| Keywords: | biomass deoxygenation glycerol homogeneous catalysis hydrogenation |
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