Branched Diol Monomers from the Sequential Hydrogenation of Renewable Carboxylic Acids

Abstract

AbstractA prominent challenge in replacing petrochemical polymers with bioderived alternatives is the efficient transformation of biomass into useful monomers. In this work, we demonstrate a practical process for the synthesis of multifunctional alcohols from five‐ and six‐carbon acids using heterogeneous catalysts in aqueous media. Design of this process was guided by thermodynamic calculations, which indicate the need for two sequential high‐pressure hydrogenations: one, reduction of the acid to a lactone at high temperature; two, further reduction of the lactone to the corresponding diol or triol at low temperature. For example, the conversion of mesaconic acid into (α or β)‐methyl‐γ‐butyrolactone was achieved with 95 % selectivity at a turnover frequency of 1.2 min−1 over Pd/C at 240 °C. Subsequent conversion of (α or β)‐methyl‐γ‐butyrolactone into 2‐methyl‐1,4‐butanediol was achieved with a yield of 80 % with Ru/C at 100 °C. This process is an efficient method for the production of lactones, diols, and triols, all valuable monomers for the synthesis of bioderived branched polyesters.