Kolbe Electrolysis of Long‐Chain Fatty Acids for Efficient Production of Bio‐Based Hydrophobic Paraffin Waxes

Herein, we present a comparative study on the Kolbe electrolysis of fatty acids. First, key parameters such as solvent composition and starting pH were briefly investigated with myristic acid (C14 : 0) as model fatty acid using a platinized titanium (Pt−Ti) anode involving the emerging liquid wax as environmentally friendly cosolvent. Second, the parameters were verified by experiments with fatty acids of different chain length (C10 : 0 to C18 : 0) which led to excellent results in the electrolysis of lauric acid (C12 : 0) with a current efficiency of 51±2 % after applying 1 FE. Comparable results (47±2 %) were obtained with a boron doped diamond anode (BDD). With current efficiencies of 45±1 % (Pt−Ti) and 46±1 % (BDD), the results were successfully transferred to an artificial fatty acid mixture as found in bio‐based coconut oil. Thus, a green and efficient method to produce bio‐based paraffin waxes on a multi‐gram scale was developed. The high hydrophobicity of the obtained waxes was validated by water contact angle measurements. Kolbe‐electrolysis is not only feasible with medium‐chain fatty acids but can be used to convert long‐chain fatty acids to bio‐based paraffin waxes in a green solvent mixture. In this systematic study, high efficiencies are achieved using single fatty acids or an artificial coconut oil blend utilizing BDD or Pt−Ti anodes.