New Approach to Renewable Aromatics

New Approach to Renewable Aromatics

Author: Veronika Belusa

Ed de Jong, Avantium Chemicals, Amsterdam, Pieter C. Bruijnincx, Utrecht University, Daan S. van Es, Wageningen University and Research Center, all The Netherlands, and colleagues have modified the classical two-step approach to furanics-derived aromatics via, Diels–Alder (DA) aromatization, into a three-step procedure to avoid retro-DA reactions.

The new synthesis involves DA addition, followed by a mild hydrogenation step to obtain a stable oxanorbornane intermediate and to prevent any retro-DA reactivity during aromatization. This dramatically enhances the overall aromatics yield for the diene/dienophile combinations studied.

Subsequent one-pot, liquid-phase dehydration and dehydrogenation of the hydrogenated adduct using a physical mixture of two types of solid catalysts, acidic zeolites or resins in combination with metal on a carbon support (Pd/C) allows aromatization. A lactone is identified as the primary intermediate of the reaction and found to be an important precursor to all aromatic products formed in the process. Yields are as high as 84 % of total aromatics under relatively mild conditions.

According to the researchers, the new route is more generally applicable and can serve as a solution for other DA-aromatization reactions limited by the thermal stability of the intermediate adduct.


 

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