Alternate Biobased Route To Produce δ-Decalactone: Elucidating the Role of Solvent and Hydrogen Evolution in Catalytic Transfer Hydrogenation

Abstract

A widely used food and flavor compound, δ-decalactone (DDL), was produced from catalytic transfer hydrogenation of 6-amyl-α-pyrone (6PP), which is a biomass-based platform chemical derived through a fermentation process. The liquid phase reaction may serve as a platform to develop an integrated bio- and chemo-catalytic process for the green synthesis of DDL from lignocellulosic biomass. The catalytic transformation of 6PP to DDL was performed under mild thermal and pressure conditions over a Pd/C catalyst using formic acid as the in situ hydrogen source. The reaction in the presence of formic acid underwent complete conversion (∼99% at 433 K in 10 min) of 6PP via progressive hydrogenation of the unsaturation present in the 2-pyrone ring, leading to 79% maximum yield of DDL. On reducing the temperature from 433 to 383 K, DDL yield was observed to reduce from 79% to 2%. An ab initio microkinetic model (MKM) was constructed to understand the decomposition of formic acid with temperature variations. The MKM p...