Etherification Reactions of Furfuryl Alcohol in the Presence of Orthoesters and Ketals: Application to the Synthesis Furfuryl Ether Bio-Fuels

Strategies for the efficient transformation of abundant and sustainable bio-derived molecules, such as furfuryl alcohol (FAlc), into higher value products is currently a vibrant research area. Herein, we demonstrate that furfuryl ethers, which are of significant interest as bio-renewable fuel additives, are efficiently produced employing an etherification reaction of furfuryl alcohol and short chain alkyl alcohols in the presence of a recyclable ZSM-5 catalyst and an orthoester, such as trimethyl orthoformate (TMOF) or triethyl orthoformate (TEOF), used as a sacrificial reagent. These etherification reactions proceed at significantly low temperatures than previous etherification procedures, and provide the furfuryl ether products in high yield. Importantly, the low temperature employed improves selectivity by minimizing the formation of hydrolysis products, and the competing polymerization reactions leading to humin by-products. By carrying out the reaction in higher alcohol solvents, such as ethanol, 1-propanol and 1-butanol, it is possible to capitalize on the ability of ZSM-5 to catalyze the orthoester exchange reaction of TMOF or TEOF to produce the corresponding furfuyl ethers in a novel, telescoped orthoester exchange-etherification reaction sequence. Finally, we also demonstrate that the etherification reaction proceeds efficiently in the presence of acetals and ketals, such as dimethoxy propane (DMOP) and diethoxypropane (DEOP). This latter development is highly significant given the greater scope for the regeneration of acetal and ketal reagents.