Conversion of Furfural Derivatives to 1,4-Pentanediol and Cyclopentanol in Aqueous Medium Catalyzed by trans-[(2,9-Dipyridyl-1,10-phenanthroline)(CH₃CN)₂Ru](OTf)₂

The complex trans-[(2,9-dipyridyl-1,10-phenanthroline)(CH₃CN)₂Ru](OTf)₂ was synthesized and tested as a homogeneous hydrodeoxygenation catalyst for the conversion of biomass-derived furfuryl alcohol and furfuryl acetate to 1,4-pentanediol (as the primary target compound) and cyclopentanol (formed by the competing Piancatelli rearrangement) in aqueous reaction medium at elevated temperature (150-200 °C) and hydrogen pressure (800 psi = 5.12 MPa). Catalytic reactions using furfuryl alcohol as a substrate were limited by the formation of solid resins with the product yields showing a strong negative correlation with increasing substrate concentration and maximum yields of 1,4-pentanediol and cyclopentanol being 23 and 41%, respectively. A two-level full factorial design of experiments study with four independent input variables (temp., time, [cat.], [substrate]) and a center point was carried out for the conversion of furfuryl acetate, showing good reproducibility between replicates and no humin formation. This enabled a full statistical analysis of the input variable impact on product distribution and yield. The maximum yields of 1,4-pentanediol and cyclopentanol using furfuryl acetate as a substrate are 68 and 35%, respectively. The decreased self-reactivity of furfuryl acetate versus furfuryl alcohol dramatically increases the yields of target products but still shows a strong negative correlation of the yield of the desired products with increasing substrate concentration.