Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
43849 | Applied Catalysis A: General | 2006 | 6 Pages |
Different Cu catalysts have been used for the hydrogenation of very low value mint oils, namely, dementholized cornmint oil and Spanish pennyroyal oil.During the hydrogenation of dementholized oil Cu/Al2O3 showed the best activity and selectivity towards a mixture of menthols, while stereoselectivity toward the valuable isomer (−)-menthol can be improved by selectively dehydrogenating the products mixture.In the hydrogenation of pulegone and pennyroyal oil Cu/Al2O3 showed an unprecedented activity allowing complete transformation of the substrate into menthols under very mild experimental conditions (1 atm H2, 90 °C). Moreover, a dynamic kinetic resolution process taking place during the hydrogenation step, allows to enrich the mixture in (−)-menthol.
Graphical abstractOne pot selective hydrogenation of (+)-pulegone to menthols can be obtained by using a heterogeneous copper catalyst under very mild experimental conditions. Stereoselectivity to (−)-menthol can be improved from 23 to 41% by exploiting a dynamic kinetic resolution over the same catalyst in a one pot-one step process. Figure optionsDownload full-size imageDownload as PowerPoint slide