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|Section2= |Section3= |Section5= |Section8= }} Carbon suboxide, or tricarbon dioxide, is an oxide of carbon with chemical formula C3O2 or O=C=C=C=O. Its four cumulative double bonds make it a cumulene. It is one of the stable members of the series of linear oxocarbons O=C''n''=O, which also includes carbon dioxide (CO2) and pentacarbon dioxide (C5O2). The substance was discovered in 1873 by Benjamin Brodie by subjecting carbon monoxide to an electric current. He claimed that the product was part of a series of "oxycarbons" with formulas C''x''+1O''x'', namely C, C2O, C3O2, C4O3, C5O4, ..., and to have identified the last two;〔 ()〕 however only C3O2 is known. In 1891 Marcellin Berthelot observed that heating pure carbon monoxide at about 550 °C created small amounts of carbon dioxide but no trace of carbon, and assumed that a carbon-rich oxide was created instead, which he named "sub-oxide". He assumed it was the same product obtained by electric discharge and proposed the formula C2O.〔 〕 Otto Diels later stated that the more organic names dicarbonyl methane and dioxallene were also correct. It is commonly described as an oily liquid or gas at room temperature with an extremely noxious odor. ==Synthesis== It is synthesized by warming a dry mixture of phosphorus pentoxide (P4O10) and malonic acid or the esters of malonic acid. Therefore, it can be also considered as the anhydride of malonic anhydride, i.e. the "second anhydride" of malonic acid. Malonic anhydride (not to be confused with maleic anhydride) is a real molecule. Several other ways for synthesis and reactions of carbon suboxide can be found in a review from 1930 by Reyerson. Carbon suboxide polymerizes spontaneously to a red, yellow, or black solid. The structure is postulated to be poly(α-pyronic), similar to the structure in 2-pyrone (α-pyrone). In 1969, it was hypothesized that the color of the Martian surface was caused by this compound; this was disproved by the Viking Mars probes (the red color is instead due to iron oxide.) 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「carbon suboxide」の詳細全文を読む スポンサード リンク
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