A sustainable and environmental benign catalytic process for the production of valuable flavors and fragrances from lignin platform chemicals

Abstract

Recent achievements in lignin depolymerization deliver various platform chemicals with high yields and provide great potential for further upgrading to value-added high-end products. 4-propylguaiacol as one of the most widely reported products via lignin-first depolymerization approach has been upgraded to a lot of valuable chemicals including polymer and pharma intermediates. In this work, we moved the focus to the field of flavors and fragrances, and proposed an environmental-friendly synthesis route to get the alternative of 4-tert-butylcyclohexyl acetate (an important fragrance ingredient with annual production of more than 1000 metric tonnes). The key for the methodology is the design and development of the Raney NiCu catalyst which prepared by ball milling and dealloying process. The obtained catalysts show improved activity compared to widely used Raney Ni catalyst and the highest yield of 87.8% for 4-propylcyclohexanol could be achieved at 160 °C when use 2-propanol as hydrogen donor. The second step aims to get 4-propylcyclohexyl acetate via esterification of 4-propylcyclohexanol with acetic acid. This could be proceeded at 90 °C via Amberlyst-15 catalyst with the highest yield of 88.3%. The proposed process presents the potential to produce the biobased flavors and fragrances in a sustainable way.