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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.
P 1845 (OTTO) Phthalic anhydride, 99% Cas 85-44-9 - used in the manufacture of materials such as artificial resins.