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IUPAC name Pyran-2-one
Other names α-Pyrone
CAS number 504-31-4
PubChem 68154
Molecular formula C5H4O2
Molar mass 96.08
Density 1.197 g/mL
Boiling point

102-103 °C at 20 mmHg

Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

2-Pyrone (α-pyrone or pyran-2-one) is an unsaturated cyclic chemical compound with the molecular formula C5H4O2. It is isomeric with 4-pyrone.

2-Pyrone is used in organic synthesis as a building block for more complex chemical structures because it may participate in a variety of cycloaddition reactions to form bicyclic lactones. For example, it readily undergoes Diels-Alder reactions with alkynes producing, upon loss of carbon dioxide, substituted benzenes.[2]

2-Pyrone also forms the the core structure of a variety of natural organic compounds. For example, the coumarins are an important class of compounds which are benzo-fused derivatives of 2-pyrone.


  1. ^ 2H-Pyran-2-one at Sigma-Aldrich
  2. ^ Woodard BT, Posner G H. "Recent Advances in Diels-Alder Cycloadditions Using 2-Pyrones." Advances in Cycloaddition. 1999, 5, 47-83.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "2-Pyrone". A list of authors is available in Wikipedia.
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