2(5H)-FURANONE, 5-ETHYLIDENE- 3690-50-4 4-Hydroxyhexa-2,4-dienoic acid lactone 5-Ethylidenefuran-2(5H)-one EINECS 223-000-4 Ethylidene-2(5H)-furanone Methyl protoanemonin Sorbic acid, 4-hydroxy-, gamma-lactone