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|Section2= }} Acetoacetic acid (also diacetic acid) is the organic compound with the formula CH3COCH2COOH. It is the simplest beta-keto acid group and like other members of this class is unstable. The methyl and ethyl esters, which are quite stable, are produced on a large scale industrially as precursors to dyes.〔 == Synthesis and properties == In general, the esters are prepared from diketene by treatment with alcohols.〔Franz Dietrich Klingler, Wolfgang Ebertz "Oxocarboxylic Acids" in Ullmann's Encyclopedia of Industrial Chemistry 2005, Wiley-VCH, Weinheim. 〕 Acetoacetic acid can be prepared by the hydrolysis of the ethyl acetoacetate followed by acidification of the anion.〔 〕 In general, acetoacetic acid is generated at 0 °C and used in situ immediately.〔George A. Reynolds and J. A. VanAllan "Methylglyoxal-ω-Phenylhydrazone" Organic Syntheses, Collected Volume 4, p.633 (1963).http://www.orgsyn.org/orgsyn/pdfs/CV4P0633.pdf〕 It decomposes at a moderate rate to acetone and carbon dioxide: :CH3C(O)CH2CO2H → CH3C(O)CH3 + CO2 The acid form has a half-life of 140 minutes at 37 °C in water, whereas the basic form (the anion) has a half-life of 130 hours. That is, it reacts about 55 times more slowly. It is a weak acid (like most alkyl carboxylic acids) with a pKa of 3.58. 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「acetoacetic acid」の詳細全文を読む スポンサード リンク
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