Control in Advanced Biofuels Synthesis via Alcohol Upgrading: Catalyst Selectivity to <i>n</i> ‐Butanol, <i>sec</i> ‐Butanol or Isobutanol

Ruthenium complexes with tetradentate PNNP donor ligands demonstrate a marked change in selectivity compared to analogous bis bidentate PN Guerbet catalysis, producing mixtures of n-butanol (17 %), sec-butanol (14 %) and ethyl acetate (66 rather than the usual 90 %+ n-butanol. Tridentate PNP ruthenium such as [Ru(H)(Cl)(CO)(Ph2PCH2CH2NHCH2CH2PPh2)] also produce and, optimized conditions (120 °C, 10 mol% NaOEt base), achieve 71 % this butanol isomer. The same tri- are efficient catalysts for conversion methanol/ethanol isobutanol (up 97 selectivity). In way, judicious choice ligand within general catalyst family allows three isomers interest fuel molecules.