An innovative approach for fatty acid reduction to fatty aldehydes

Abstract

The increasing demand for fatty aldehydes as natural flavoring agents nowadays grapples with current production processes requiring harsh reaction conditions and hazardous chemicals. Our research group proved the concept of an innovative, sustainable process based on renewable plant oils for fatty aldehyde production: fatty acids reduction via zerovalent iron. In this study, we present for the first time extensive supporting data characterizing the metal particles used as co-reactants and the core step of the reaction, with varying process parameters. Furthermore, process improvement is demonstrated in that addition of fatty ester-obtained alcohol regenerates metal particles, thereby increasing process yield and selectivity as well as avoiding resource waste. Hexanoic acid reduction to hexanal in the presence of iron particles was used as a reference reaction system, generating a 40% hexanoic acid conversion using Fe 36 µm-particles. To increase overall process sustainability, we explored the possibility of an in toto exploitation of the starting materials (esters) through an a posteriori reduction of the oxidized iron, exemplarily with the alcohol hexanol. The hexanoic acid conversion rate was thereby increased to 83%, while a 44-fold increase in hexanal yield was observed.