| 释义 |
pyran Chem.|ˈpaɪəræn|
Also -ane |-eɪn|.
[f. pyrone + -an, -ane.]
a. A heterocyclic compound, C5H6O, having a doubly unsaturated six-membered ring consisting of five carbon atoms and one oxygen atom; two isomers (differing in the positions of the double bonds) are possible, only one of which, CH2CH:CH·CH:CH·O (γ-pyran), has been isolated, as a colourless, unstable oil.
b. Any derivative of either isomer containing a pyran ring. Freq. attrib., as pyran ring, a ring (which may be saturated) of five carbon atoms and one oxygen atom.
[1901Jrnl. Chem. Soc. LXXX. i. 559 7-Hydroxy-2-phenyl-4-methylbenzopyran.] 1904Ibid. LXXXVI. i. 816 (heading) Properties of oxygen in the pyran ring. 1927Ibid. 3139 The normal sugars are thus seen to be representatives of the parent form indicated by pyran and the labile or γ-sugars have as their parent substance furan. 1952K. Venkataraman Chem. Synthetic Dyes II. xxiv. 742 The γ-pyran ring..occurs in the anthocyanins, the red, violet and blue coloring matters of flowers and fruits. 1953Fruton & Simmonds Gen. Biochem. xvii. 374 The ring in the cyclic form of glucose is related to the heterocyclic compound pyrane. 1962Jrnl. Amer. Chem. Soc. LXXXIV. 2453/1 γ-Pyran is extremely unstable at room temperature, particularly when exposed to air. 1965Kice & Marvell Mod. Princ. Org. Chem. xix. 360 The two double bonds can be conjugated or unconjugated, and two types of pyran rings are known. Ibid., Like enol ethers in general these rings are unstable, and α-pyran itself is unknown. |