Pyran

Pyran  |

2H-pyran

4H-pyran

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|  |

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Names
IUPAC name

2H-Pyran, 4H-Pyran

Other names

2H-Oxine, 4H-Oxine

Identifiers

CAS Number

* 289-66-7 (2H) Y
* 289-65-6 (4H) Y

3D model (JSmol)

* (2H): Interactive image
* (4H): Interactive image

ChemSpider |

* 161812 (2H) Y
* 119912 (4H) Y

PubChem CID

* 186148 (2H)
* 136135 (4H)

UNII |

* CH5P2A5WTT Y

InChI

* (2H): InChI=1S/C5H6O/c1-2-4-6-5-3-1/h1-4H,5H2

Key: MGADZUXDNSDTHW-UHFFFAOYSA-N

* (4H): InChI=1S/C5H6O/c1-2-4-6-5-3-1/h2-5H,1H2

Key: MRUWJENAYHTDQG-UHFFFAOYSA-N

SMILES

* (2H): C1=CC=CCO1

* (4H): C1=CCC=CO1

Properties

Chemical formula

| C5H6O
Molar mass | 82.102 g·mol−1
Related compounds

Related compounds

| Dihydropyran
Tetrahydropyran

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Infobox references

Chemical compound

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.[1]

4H-Pyran was first isolated and characterized in 1962 via pyrolysis of 2-acetoxy-3,4-dihydro-2H-pyran.[2] 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.

Although the pyrans themselves have little significance in chemistry, many of their derivatives are important biological molecules, such as the pyranoflavonoids.[citation needed]

The term pyran is also often applied to the saturated ring analog, which is more properly referred to as tetrahydropyran (oxane). In this context, the monosaccharides containing a six-membered ring system are known as pyranoses.

## See also

[edit]

* Benzene
* Pyranose
* Furan
* Furfural
* Pyridine
* Pyrone
* Thiopyran

## References

[edit]

1. ^ "Blue Book chapter P-2". iupac.qmul.ac.uk. Retrieved 2025-02-05.
2. ^ Masamune, S.; Castellucci, N. T. (1962). "γ-Pyran". Journal of the American Chemical Society. 84 (12): 2452–2453\. doi:10.1021/ja00871a037.

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