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An oxocarbon or oxide of carbon is a chemical compound consisting only of carbon and oxygen.〔 〕〔R. West, editor (1980), ''Oxocarbons''. Academic Press, New York.〕 The simplest and most common oxocarbons are carbon monoxide (CO) and carbon dioxide (CO2). Many other stable or metastable oxides of carbon are known, but they are rarely encountered, such as carbon suboxide (C3O2 or O=C=C=C=O) and mellitic anhydride (C12O9). While textbooks will often list only the first three, and rarely the fourth, a large number of other oxides are known today, most of them synthesized since the 1960s. Some of these new oxides are stable at room temperature. Some are metastable or stable only at very low temperatures, but decompose to simpler oxocarbons when warmed. Many are inherently unstable and can be observed only momentarily as intermediates in chemical reactions or are so reactive that they can exist only in the gas phase or under matrix isolation conditions. The inventory of oxocarbons appears to be steadily growing. The existence of graphene oxide and of other stable polymeric carbon oxides with unbounded molecular structures〔〔 suggests that many more remain to be discovered. ==Overview== Carbon dioxide (CO2) occurs widely in nature, and was incidentally manufactured by humans since pre-historical times, by the combustion of carbon-containing substances and fermentation of foods such as beer and bread. It was gradually recognized as a chemical substance, formerly called ''spiritus sylvestre'' ("forest spirit") or "fixed air", by various chemists in the 17th and 18th centuries. Carbon monoxide may occur in combustion, too, and was used (though not recognized) since antiquity for the smelting of iron from its ores. Like the dioxide, it was described and studied in the West by various alchemists and chemists since the Middle Ages. Its true composition was discovered by William Cruikshank in 1800. Carbon suboxide was discovered by Brodie in 1873, by passing electric current through carbon dioxide.〔 〕 The fourth "classical" oxide, mellitic anhydride (C12O9), was apparently obtained by Liebig and Wöhler in 1830 in their study of mellite ("honeystone"), but was characterized only in 1913, by Meyer and Steiner.〔 J. Liebig, F. Wöhler (1830), ''Ueber die Zusammensetzung der Honigsteinsäure'' Poggendorfs Annalen der Physik und Chemie, vol. 94, Issue 2, pp.161–164. (Online version ) accessed on 2009-07-08. 〕〔 〕〔 Bugge (1914), ''Chemie: En neues Kohenoxyd.'' Review of Meyer and Steiner's discovery of C12O9. Naturwissenschaftliche Wochenschrift, volume 13/29, issue 12, 22 March 1914, p. 188. (Online version ) accessed on 2009-07-09. 〕 Brodie also discovered in 1859 a fifth compound called graphite oxide, consisting of carbon and oxygen in ratios varying between 2:1 and 3:1; but the nature and molecular structure of this substance remained unknown until a few years ago, when it was renamed graphene oxide and became a topic of research in nanotechnology.〔 Notable examples of unstable or metastable oxides that were detected only in extreme situations are dicarbon monoxide radical (:C=C=O), carbon trioxide (CO3),〔 〕 carbon tetroxide (),〔 Laurence Y. Yeung, Mitchio Okumura, Jeffrey T. Paci, George C. Schatz, Jianming Zhang and Timothy K. Minton (2009), ''Hyperthermal O-Atom Exchange Reaction O2 + CO2 through a CO4 Intermediate.'' J. of the American Chemical Society, volume 131, issue 39, pages 13940–13942. 〕〔 〕 carbon pentoxide (), carbon hexoxide () and 1,2-dioxetanedione (C2O4).〔 Herman F. Cordes, Herbert P. Richter, Carl A. Heller(1969), ''Mass spectrometric evidence for the existence of 1,2-dioxetanedione (carbon dioxide dimer). Chemiluminescent intermediate.'' J. Am. Chem. Soc., 1969, 91 (25), p 7209. 〕〔 Richard Bos, Neil W. Barnett, Gail A. Dyson, Kieran F. Lim, Richard A. Russell and Simon P. Watson (2003), ''Studies on the mechanism of the peroxyoxalate chemiluminescence reaction: Part 1. Confirmation of 1,2-dioxetanedione as an intermediate using 13C nuclear magnetic resonance spectroscopy''. Analytica Chimica Acta, Volume 502, Issue 2, 30 January 2004, Pages 141-147. 〕 Some of these reactive carbon oxides were detected within molecular clouds in the interstellar medium by rotational spectroscopy.〔 H. M. Pickett E. A. Cohen B. J. Drouin J. C. Pearson (2003), ''Submillimeter, Millimeter, and Microwave Spectral Line Catalog''. NASA/JPL, (Online version ) accessed on 2009-07-11. 〕 Many hypothetical oxocarbons have been studied by theoretical methods but have yet to be detected. Examples include oxalic anhydride (C2O3 or O=(C2O)=O), ethylene dione (C2O2 or O=C=C=O)〔 and other linear or cyclic polymers of carbon monoxide (-CO-)''n'' (polyketones),〔 Haijun Jiao and Hai-Shun Wu (2003), ''Are Neutral Oxocarbons Stable?'' J. Org. Chem., volume 68, 1475-1479. 〕 and linear or cyclic polymers of carbon dioxide (-CO2-)''n'', such as the dimer 1,3-dioxetanedione (C2O4)〔 and the trimer 1,3,5-trioxanetrione (C3O6).〔 Errol Lewars(1996), ''Polymers and oligomers of carbon dioxide: ab initio and semiempirical calculations''. Journal of Molecular Structure: THEOCHEM, Volume 363, Number 1, pp. 1–15 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「oxocarbon」の詳細全文を読む スポンサード リンク
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