ketene

/kee"teen/, n. Chem.
a colorless, poisonous gas, C2H2O, irritating to the lungs, prepared from acetone or acetic acid by pyrolysis: used chiefly in the manufacture of certain commercial chemicals, as acetic anhydride and aspirin.
[1905-10; KET- + -ENE]

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      any of a class of organic compounds (organic compound) containing the functional grouping C=C=O; the most important member of the class being ketene itself, CH2=C=O, which is used in the manufacture of acetic anhydride and other industrial organic chemicals. The name suggests that ketenes are unsaturated ketones (ketone), but their chemistry resembles that of carboxylic acid anhydrides.

      Ketene is prepared by heating acetic acid or acetone to about 700 °C (1,300 °F).

      Ketene is remarkably reactive; it combines with compounds containing an easily replaced hydrogen atom to yield derivatives of acetic acid. The only important industrial use of ketene itself is its reaction with acetic acid to form acetic anhydride.

      Ketene reacts with aldehydes (aldehyde) and ketones to form enol acetates or β-lactones (lactone).

      In the absence of a reactive substrate, ketene combines with itself to form diketene, a β-lactone used industrially to prepare derivatives of acetoacetic acid, such as ethyl acetoacetate and acetoacetamides.

      The higher ketenes are generally synthesized by elimination of hydrogen chloride from acyl chlorides. The substituted ketenes react like ketene, but less vigorously. The lactone dimers of long-chain monoalkylketenes have been used as sizing agents for paper.

      Ketene, a colourless, irritant gas, is toxic, producing delayed respiratory damage. The high reactivity of all ketenes makes them somewhat dangerous.

William H. Brown
 

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Universalium. 2010.

Look at other dictionaries:

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  • ketene — [kē′tēn΄] n. [ KET(O) + ENE] 1. a colorless, toxic gas, H2C∶CO, with a penetrating odor, made by passing acetone or acetic acid through hot metal tubes: used esp. as an acetylating agent 2. any of a series of related organic compounds containing… …   English World dictionary

  • Ketene — A ketene is an organic compound of the form R2C=C=O. Hermann Staudinger pioneered the research of ketenes. [cite journal title = Ketene, eine neue Körperklasse author = Hermann Staudinger journal = Berichte der deutschen chemischen Gesellschaft… …   Wikipedia

  • ketene — ketenas statusas T sritis chemija formulė H₂C=C=O atitikmenys: angl. keten; ketene rus. кетен …   Chemijos terminų aiškinamasis žodynas

  • ketene — ketenas statusas T sritis chemija formulė R₂C=C=O atitikmenys: angl. keten; ketene rus. кетен …   Chemijos terminų aiškinamasis žodynas

  • ketene — noun Etymology: International Scientific Vocabulary Date: 1907 a colorless poisonous gas C2H2O of penetrating odor used especially as an acetylating agent; also any of various derivatives of this compound …   New Collegiate Dictionary

  • ketene — noun any of a class of unsaturated ketones, having a general formula RR …   Wiktionary

  • ketene — 1. CH2=C=O; a very reactive acetylating agent, used in chemical syntheses. 2. Any substituted k.. * * * ke·tene kē .tēn n a colorless poisonous gas C2H2O of penetrating odor used esp. as an acetylating agent also any of various derivatives of… …   Medical dictionary

  • ketene — n. colorless poisonous gas used mainly in the manufacture of cellulose acetate and aspirin (Chemistry) …   English contemporary dictionary

  • ketene — ke·tene …   English syllables

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