Journal of Molecular Catalysis A-Chemical, Vol.277, No.1-2, 233-251, 2007
Catalytic deoxygenation of terminal-diols under acidic aqueous conditions by the ruthenium complexes [(eta(6)-arene)Ru(X)(N boolean AND N)](OTf)(n), X = H2O, H, eta(6)-arene =p-Me-Pr-i-C6H4, C6Me6, N boolean AND N = bipy, phen, 6,6'-diamino-bipy, 2,9-diamino-phen, n=1, 2) Influence of the ortho-amine substituents on catalytic activity
A series of ruthenium complexes of the general composition [(eta(6) -arene)(N boolean AND N)Ru(X)] (Y)(n), (arene = p-Me-Pr-i-C6H4, C6Me6; N boolean AND N = bipy, phen, 6,6'-diamino-2,2'-bipyridine, 2,9-diamino-1,10-phenanthroline; X=Cl, H, H2O; Y=Cl, OTf) was synthesized and the new compounds exhaustively structurally characterized by standard techniques (NMR, IR, elemental analysis, single-crystal X-ray crystallography). The single-crystal X-ray structures of [(p-Me-Pr-i-C6H4)Ru(dabipy)Cl][CI] (3CI[CI]), [(p-Me-Pr-i-C6H4)Ru(daphen)CI][CI] (4CI[CI]), [(C6Me6)Ru(dabipy)CI][CI] (7CI[CI]), [(C6Me6)Ru(daphen)CI][CI] (8CI[OTf]), [(p-Me-Pr-i-C6H4)Ru(bipy)(H2O)][OTf](2) (1O[OTf](2)), [(p-Me-Pr-i-C6H4)Ru(dabipy)(H2O)][OTf](2) (3O[OTf](2)), [(p-Me-Pr-i-C6H4)Ru(dabipy)(H2O)][SO4] (3O[SO4]), [(P-Me-(PrC6H4)-Pr-i)-Ru(daphen)(H2O)][OTf](2) (4O[OTf](2)), [(C6Me6)Ru(daphen)(MeOH)][OTf](2) (8(MeOH)[OTf](2)), [(p-Me-Pr-i-C6H4)Ru(dabipy)(H)][OTf] (3H[OTf]), [(p-Me-Pr-i-C6H4)Ru(daphen)(H)][OTf] (4H[OTf]), [(C6Me6)Ru(dabipy-BH2-OTf)(H)] (7H[-NH2-BH2-OTf]) have been determined. Under 750-1100 psi (5-7.5 MPa) of hydrogen pressure at 110 degrees C in the presence of acid and water in sulfolane solvent the aquo complexes form active catalysts for the selective deoxygenation of terminal diols, notably 1,2-hexanediol, to the corresponding primary alcohol, i.e., 1-hexanol in up to 60% yield. The presence of amino functions on the ortho-positions of the chelating ligands results in lower catalyst activity. Under the same reaction conditions the catalysts fail to convert glycerol to GC-detectable products. At the higher temperatures (T> 150 degrees C) possibly required for glycerol activation the catalysts show increasing decomposition with increasing temperature. (C) 2007 Elsevier B.V. All rights reserved.