Oxidative Aromatization of Biobased Chemicals to Benzene Derivatives through Tandem Catalysis

Petroleum-derived aromatic compounds play irreplaceable roles in an extremely broad spectrum of industries. Production of value-added aromatic chemicals from renewable resources has been attractive and yet remains a great challenge for sustainable chemistry. We report herein a tandem catalytic oxidative aromatization approach that converts eucalyptus oil mixtures, renewable furans and dienes + dienophiles, to structurally diversified benzene derivatives. Eucalyptus oil mixtures undergo tandem dehydration-oxidative dehydrogenation to p-cymene. The Diels-Alder reaction between furans and dienophiles provides 7-oxanorbornene intermediates, which must be hydrogenated before dehydration-oxidative dehydrogenation to benzenoids in order to prevent retro-Diels-Alder side reactions. Cyclohexene intermediates resulted from DA reactions between nonfuran dienes and dienophiles undergo oxidative dehydrogenation to benzenoids. A heteropoly acid silicomolybdic acid acts as the catalyst, and molecular oxygen is the terminal oxidant for the key oxidative dehydrogenation reaction that is common for all the above reactions. These multistep sequences of reactions can be achieved in one pot without separation of intermediates.