/puy"ran, puy ran"/, n. Chem.
either of two compounds having the formula C5H6O, containing one oxygen and five carbon atoms arranged in a six-membered ring.
[1900-05; PYR(ONE) + -an, var. of -ANE]

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      any of a class of organic compounds of the heterocyclic series in which five carbon atoms and one oxygen atom are present in a ring structure. Of two possible simple pyran compounds, only one is known; it was prepared in 1962 and found to be very unstable. Among the stable members of this family is tetrahydropyran, made by hydrogenating the dihydro compound. Sugars often occur in pyranose forms containing the tetrahydropyran ring: a typical example is the glucose unit present in sucrose, starch, cellulose, and glycogen.

      In the pyrones, a carbonyl group (>C=O) replaces the methylene group (>CH2) of the pyrans. The toad venoms and the toxic principles of squill are pyrones of the steroid family.

      The pyrylium salts are coloured substances in which the pyran ring exists as a positively charged ion. The closely related flavylium salts occur as pigments in the rose, the blue cornflower, and certain other flowers.

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Universalium. 2010.

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Look at other dictionaries:

  • pyran — [pī′ran΄, pī ran′] n. [ PYR(ONE) + AN] any of a group of closed chain compounds containing a ring, C5H6O, of one oxygen atom and five carbon atoms …   English World dictionary

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  • pyran — ˈpīˌran noun ( s) Etymology: International Scientific Vocabulary pyr + an : either of two parent cyclic compounds C5H6O that contain five carbon atoms and one oxygen atom in the ring: a. : the alpha isomer called also 2H pyran …   Useful english dictionary

  • pyran — piranas statusas T sritis chemija apibrėžtis Šešianaris heterociklinis junginys. formulė C₅H₆O atitikmenys: angl. pyran rus. пиран …   Chemijos terminų aiškinamasis žodynas

  • Pyran-2-one — 2 pyrone Général Nom IUPAC 2H pyran 2 one Synonymes α pyrone, pyran 2 one …   Wikipédia en Français

  • Pyran-4-one — 4 pyrone Général Nom IUPAC 4H pyran 4 one Synonymes γ pyrone …   Wikipédia en Français

  • pyran — noun Etymology: International Scientific Vocabulary Date: 1904 either of two cyclic compounds C5H6O that contain five carbon atoms and one oxygen atom in the ring …   New Collegiate Dictionary

  • pyran — noun Any of a class of heterocyclic compounds containing a ring of five carbon atoms and an oxygen atom; especially the simplest one, CHO. Syn: furan …   Wiktionary

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