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Phthalaldehyde

o-Phthalaldehyde or ortho-phthalaldehyde (OPA) is the chemical compound with the formula CH(CHO). Often abbreviated OPA, the molecule is a di aldehyde, 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.