Direct conversion of glucose to 5-(hydroxymethyl)furfural in ionic liquids with lanthanide catalysts

The direct conversion of glucose to 5-(hydroxymethyl)furfural (HMF) in ionic liquids with lanthanide catalysts was examined in search of a possibly more environmentally feasible process not involving chromium. The highest HMF yield was obtained with ytterbium chloride or triflate together with alkylimidazolium chlorides. Notably, a higher reactivity was observed when the hydrophobicity of the imidazolium cation was increased, in contrast to analogous chromium catalyst systems. This indicates a different reaction mechanism for the lanthanides than for the chromium catalyst systems.