2-Furanone is a heterocyclic organic compound. It is also known as ó-crotonolactone (GCL), as it is formally the lactone derived from ó-hydroxyisocrotonic acid. The chemical is colloquially called "butenolide", and is the parent structure for the butenolide class of compounds. It is a colourless liquid.
2-Furanone is prepared by oxidation of furfural:
It exists in equilibrium with the tautomer 2-hydroxyfuran, which serves as an intermediate in the interconversion between the ò- and ñ-furanones. The ò form is the more stable. The interconversion is catalyzed by base.
2-Furanones can be converted to furans by a two-step process of reduction followed by dehydration reaction.
Furanone is thought to contribute to the unique taste of maple syrup.