# Selective Oxygenation of 3,4‐Dihydro‐2H‐Pyran to 5,6‐Dihydro‐2H‐Pyran‐2‐One With Pd/C Catalyst and Molecular Oxygen

## TL;DR

Scientists developed a method to efficiently convert a compound from plant material into a valuable chemical using a reusable catalyst and oxygen.

## Contribution

A reusable Pd/C catalyst with base addition was found to selectively produce 5,6-dihydro-2H-pyran-2-one from lignocellulose-derived furfural with 52% yield.

## Key findings

- Pd/C catalyst with NaHCO3 base achieved 52% yield of 5,6-dihydro-2H-pyran-2-one.
- Catalyst activity was recoverable after heat treatment under H2.
- Radical scavenger reduced DHPO formation, indicating radical intermediates in the reaction.

## Abstract

The oxidation of 3,4‐dihydro‐2H‐pyran (DHP), which can be produced from lignocellulose‐derived furfural, was investigated with various catalysts and molecular oxygen as an oxidant in a H2O solvent. 5,6‐Dihydro‐2H‐pyran‐2‐one (DHPO) was obtained in moderate yield with a carbon black‐supported Pd catalyst (Pd/C). The addition of base (NaHCO3) suppressed the side reaction of DHP (i.e., hydration of DHP) and increased DHPO yield up to 52%. The activity of the catalyst was slightly decreased after three‐time use but recovered by the heat‐treatment under H2. Through the investigation of various Pd/support catalysts, the catalysts with low valent and stable Pd0 phase during the reaction, such as Pd/C and Pd/BN, showed high activity in DHPO formation. Positive and almost zero reaction orders were observed with respect to O2 pressure and DHP concentration, respectively, indicating the involvement of oxygen species in the rate‐determining step and the strong adsorption of DHP with catalyst. The addition of radical scavenger lowered the formation amount of DHPO, suggesting that a radical intermediate is involved in the reaction.

Selective oxygenation: The oxidation of 3,4‐dihydro‐2H‐pyran, which can be produced from lignocellulose‐derived furfural, was investigated with various catalysts using O2 as an oxidant in a H2O solvent. 5,6‐dihydro‐2H‐pyran‐2‐one, a value‐added product, was obtained in 52% yield with reusable Pd/C catalyst.© 2026 WILEY‐VCH GmbH