Pyran

Pyrans are two chemical compounds with the molecular formula C5H6O, which are among the oxygen-containing heterocycles. Its ring structure is formed from five carbon atoms, and an oxygen atom and contains two double bonds. This results in two isomers, the 2H- pyran or α - pyran and the 4H- pyran or γ - pyran. Pyrans are not aromatic, because not all of the carbon atoms are sp2 - hybridized.

γ - pyran is a colorless oil with a boiling point of 80 ° C, which is soluble in ethanol, benzene and diethyl ether and quickly turns brown in the air. The synthesis starts from glutaraldehyde.

Similar structures form some carbohydrates (sugars), these are called pyranose, but contain no double bonds in the ring.

Both 2H- pyran and 4H- pyran come in nature not free of them, however, derive many natural substances such as pyrones, as coumarin or colored flavones, such as luteolin from. Also some synthetic dyes and drugs are pyran derivatives.

Related compounds

• Dihydropyran
• Tetrahydropyran
• Furan