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|Section2= |Section7= }} ''o''-Phthalaldehyde or ''ortho''-phthalaldehyde (OPA) is the chemical compound with the formula C6H4(CHO)2. Often abbreviated OPA, the molecule is a dialdehyde, consisting of two formyl (CHO) groups attached to adjacent carbon centres on a benzene ring. This pale yellow solid is a building block in the synthesis of heterocyclic compounds and a reagent in the analysis of amino acids. OPA dissolves in water solution at pH < 11.5. Its solutions degrade upon UV illumination and exposure to air. ==Synthesis and reactions== The compound was first described in 1887 when it was prepared from α,α,α’,α’-tetrachloro-ortho-xylene. A more modern synthesis is similar: the hydrolysis of the related tetrabromoxylene using potassium oxalate, followed by purification by steam distillation.〔 The reactivity of OPA is complicated by the fact that in water it forms both a mono- and dihydrate, C6H4(CHO)(CH(OH)2) and C6H4(CH(OH))2O, respectively. Its reactions with nucleophiles often involves the reaction of both carbonyl groups. 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「Phthalaldehyde」の詳細全文を読む スポンサード リンク
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