Heteropoly acid catalysts in the valorization of the essential oils: Acetoxylation of β-caryophyllene

H3PW12O40 (PW), the strongest heteropoly acid in the Keggin series, is an active and environmentally friendly catalyst for the liquid-phase conversion of β-caryophyllene (1) to β-caryolanyl acetate (2) in homogeneous and heterogeneous systems. An efficient and clean method for the synthesis of 2, providing a mixture containing two stereoisomeric β-caryolanyl acetates 2a and 2b, 2a/2b = 80/20 mol/mol, with 100% GC yield, has been developed using PW as a homogeneous catalyst under mild reaction conditions. The reaction occurs at 25 °C with a catalyst turnover number of 2000. The catalyst can be recovered without neutralization and reused without loss of activity and selectivity.

Graphical abstractH3PW12O40 (PW), the strongest heteropoly acid in the Keggin series, is an active and environmentally friendly catalyst for the liquid-phase conversion of one of the most abundant sesquiterpenes, i.e., β-caryophyllene (1), to β-caryolanyl acetate (2), which is a potentially valuable fragrance compound, in up to 100% GC yield.Figure optionsDownload full-size imageDownload high-quality image (42 K)Download as PowerPoint slide