pyran


pyran
/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.

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

  • Pyran — Pyrane Name 2H Pyran 4H Pyran Andere Namen α Pyran Oxa 2,4 cyclohexadien γ Pyran, Oxa 2,5 cyclohexadien Strukturformel …   Deutsch Wikipedia

  • Pyran — Chembox new ImageFileL1=2H Pyran.png ImageSizeL1=75px ImageFileR1=Pyran3d.png ImageSizeR1=100px ImageFileL2=4H Pyran.png ImageSizeL2=75px ImageFileR2=4HPyran3d.png ImageSizeR2=100px IUPACName=Pyran OtherNames=2 H Pyran, 4 H Pyran Section1=… …   Wikipedia

  • Pyran — Py|ran [↑ Pyron u. ↑ an (4)], das; s, e: nach Lage der Doppelbindungen als 2H oder α Pyran u. 4H oder γ Pyran zu unterscheidende zweifach ungesättigte Sauerstoff Heterocyclen C5H6O, von denen bzw. von deren Ketonen (↑ …   Universal-Lexikon

  • 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 — 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

  • pyran — A cyclic compound that may be considered the formal parent of sugars with an oxygen bridge from carbon atoms 1–5 (the pyranoses). * * * py·ran pī(ə)r .an n either of two cyclic compounds C5H6O that contain five carbon atoms and one oxygen atom in …   Medical dictionary

  • Pyran — Py|ran das; s, e (meist Plur.) <zu ↑pyro... u. ↑...an> sechsgliedrige ↑heterozyklische Verbindung mit einem Sauerstoffatom im Ring (Chem.) …   Das große Fremdwörterbuch


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