Phthalic Acid → Naphthalene

Participants

Reaction Conditions

Reaction Steps

As shown in FIG. 2; A curve, when sulfuric acid is present in the aqueous slurry of naphthoquinone and phthalic acid, and the aqueous slurry is heated at higher than 80° C., naphthoquinone is vigorously decomposed. Accordingly, is it clear that when sulfuric acid is present in the aqueous slurry of naphthoquinone in the step of collecting the reaction mixture gas formed by the catalytic vapor phase oxidation of a crude naphthalene with water, the step of dissolving phthalic acid and the step of extracting naphthoquinone, the decomposition of naphthoquinone is remarkably accelerated. The inventors have studied the method of preventing the decomposition of naphthoquinone and have found that the decomposition of naphthoquinone could be prevented by adjusting the pH of the aqueous slurry of naphthoquinone and phthalic acid to 1.2 to 2.5 by neutralizing 1 to 2 equivalents of sulfuric acid and 1 equivalent of maleic acid with a base such as an aqueous solution of sodium hydroxide.

Provenance & Evidence