pyran
Sign in to saveIn chemistry, pyran is a six-membered heterocyclic, non-aromatic ring, consisting of five carbon atoms and one oxygen atom and containing two double bonds. The molecular formula is C5H6O. There are two isomers of pyran that differ by the location of the double bonds. In '2H-pyran, the saturated carbon is at position 2, whereas, in 4H-pyran', the saturated carbon is at position 4. "Oxine” is not used for pyran because it has been used as a trivial name for quinolin-8-ol.
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In chemistry, pyran is a six-membered heterocyclic, non-aromatic ring, consisting of five carbon atoms and one oxygen atom and containing two double bonds. The molecular formula is C5H6O. There are two isomers of pyran that differ by the location of the double bonds. In '2H-pyran, the saturated carbon is at position 2, whereas, in 4H-pyran', the saturated carbon is at position 4. "Oxine” is not used for pyran because it has been used as a trivial name for quinolin-8-ol.
4H-Pyran was first isolated and characterized in 1962 via pyrolysis of 2-acetoxy-3,4-dihydro-2H-pyran. It was found to be unstable, particularly in the presence of air. 4H-pyran easily disproportionates to the corresponding dihydropyran and the pyrylium ion, which is easily hydrolyzed in aqueous medium.
Excerpted from Wikipedia’s “pyran” article, available under the CC BY-SA 4.0 licence.