Synthesis of high value fragrances (dihydrolinalool and tetrahydrolinalool) using combinations of biobased mint biochar/activated charcoal incorporated Ni–Pd catalysts

Abstract

Linalool (I), a key monoterpenoid alcohol abundant in Ocimum basilicum var. CIM-Shishir (>70%), readily undergoes auto-oxidation leading to the formation of toxic by-products like oxidized linalool. Besides, harmful effects of linalool on humans as well as in the environment have been increasing rapidly. This study highlights the value addition of linalool to a more stable form via catalytic hydrogenation using biochar-supported Ni–Pd and activated charcoal. Under the optimized reaction conditions of 13 bar H₂ pressure at 150 °C with a reaction time of 60 min, the designed catalysts hydrogenate linalool (I) to 6,7-dihydrolinalool (II) and tetrahydrolinalool (III) with 82.5% and 91.6% selectivity, respectively. Catalyst characterization has confirmed the role of metal–support interactions towards governing the selectivity. The industrial potential of the present catalytic process in the synthesis of fine fragrance chemicals has been revealed.