The co-solvent H2O had a negative effect since the solubility of benzoin. While another important biomass platform compound DHMF had a better solubility in H2O, and very surprisingly, the oxidation of DHMF to BHMF in 98% could be obtained under an H2O, open-air system with 10 mol% of K2CO3 without any water trapping additives, which has not been reported yet so far.