A Pt/Nb2O5 catalyst for oxidative conversion of 1,5-pentanediol into 5-hydroxypentanal and δ-valerolactone under ambient conditions

Abstract

Hydroxyaldehydes and lactones such as 5-hydroxypentanal (5-HP) and δ-valerolactone (DVL) are important value-added feedstocks for organic synthesis and biomedical production. Usually, high temperature, organic solvents or toxic oxidants are involved in the selective oxidation of 1,5-pentanediol (1,5-PDO) to 5-HP and DVL. Here, an environmentally friendly strategy for the simultaneous synthesis of 5-HP and DVL via the efficient oxidation of 1,5-PDO using an aqueous suspension of Pt-loaded Nb₂O₅ nanoparticles under ambient conditions is proposed. The characterization results indicate that the positively charged Pt^δ+ species formed due to electronic metal–support interactions between Pt and Nb₂O₅ are beneficial for the primary dehydrogenation of 1,5-PDO to 5-HP on Pt, while the strong Lewis acid sites on Nb₂O₅ are able to improve aldol condensation and intramolecular cyclization of 5-HP to DVL.