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|Section2= |Section3= |Section7= |Section8= }} Phthalic anhydride is the organic compound with the formula C6H4(CO)2O. It is the anhydride of phthalic acid. Phthalic anhydride is a principal commercial form of phthalic acid. It was the first anhydride of a dicarboxylic acid to be used commercially. This colourless solid is an important industrial chemical, especially for the large-scale production of plasticizers for plastics. In 2000, the world wide production volume was estimated to be about 3 million tonnes per year.〔 ==Synthesis and production== Phthalic anhydride was first reported in 1836 by Auguste Laurent. More contemporary routes include catalytic oxidation of ''ortho''-xylene and naphthalene ("Gibbs phthalic anhydride process"), although use of naphthalene has declined. Starting from o-xylene, the oxidation follows the following stoichiometry: :C6H4(CH3)2 + 3 O2 → C6H4(CO)2O + 3 H2O The reaction proceeds with about 70% selectivity. About 10% of maleic anhydride is also produced: :C6H4(CH3)2 + 7.5 O2 → C4H2O3 +4 H2O + 4 CO2 The reaction is catalyzed by a vanadium pentoxide (V2O5) between 320 - 400 °C. The phthalic anhydride is separated from byproducts by a series of "switch condensers". Phthalic anhydride and maleic anhydride are recovered by distillation. Phthalic anhydride can also be prepared from phthalic acid:〔Peter M. Lorz, Friedrich K. Towae, Walter Enke, Rudolf Jäckh, Naresh Bhargava, Wolfgang Hillesheim "Phthalic Acid and Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry, 2007, Wiley-VCH, Weinheim. 〕 Large scale industrial production of maleic anhydride is achieved by unification of following unit processes: • 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「Phthalic anhydride」の詳細全文を読む スポンサード リンク
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