Method for manufacturing phthalic acid/phthalic acid anhydride

摘要

Continuous method for preparing a mixture of phthalic acid and its anhydride dissolved in an aliphatic monocarboxylic acid (preferably acetic acid), comprises oxidation of o-xylene (dissolved in monocarboxylic acid) with air oxygen in the presence of a catalyst, where the method comprises many reaction steps and the molar ratio of o-xylene to the intermediate product formed from 2-methyl benzaldehyde, 2-methylbenzoic acid and phthalide lies below 1:40 in the product stream (7) supplied to the last reaction step.