Conversion of Ethanol to 2-Ethylhexenal at Ambient Conditions Using Tandem, Biphasic Catalysis

Ethanol is a ubiquitous fermentation product well-tolerated by microbes, but purification from growth media requires multiple distillations or other energy intensive processes. Converting such metabolites to larger, hydrophobic products would both yield higher energy products and facilitate separation. Here, we demonstrate the conversion of C₂ ethanol to C₈ 2-ethylhexenal via a sequential oxidation-aldol-hydrogenation-aldol process with solar energy as the only required input. Photocatalysis was utilized to drive enzymatic oxidation of ethanol, while biphasic media in conjunction with aldol coupling and Pd assisted hydrogenation kept the oxidation and reduction processes physically and chemically separated. Using this process, 2-ethylhexenal was produced from ethanol in both buffer and diluted yeast media.