5-Hydroxy-2(5H)-furanone is a furanone derived from oxidation of furfural using singlet oxygen.

[1][2] This oxidation is carried out generally in methanol or ethanol with a sensitizer like methylene blue or Rose bengal.

5-Hydroxy-2(5H)-furanone is a potent pesticide[1] and a four carbon building block for various heterocycles.

[3][4] 5-Hydroxy-2(5H)-furanone exists in chemical equilibrium with its isomer, cis-β-formylacrylic acid, in ring-chain tautomerism:[5]

Upon heating in strongly basic solution (pH > 9) this isomer will hydrate to succinic acid.