Process for separation of naphthoquinone and phthalic acid

Details Process for separation of naphthoquinone and phthalic acid Process for separation of naphthoquinone and phthalic acid

1978-01-10

1980-05-13

Garner, Vivian

Chemistry of carbon compounds

Miscellaneous organic carbon compounds

C-metal

562408, 562485, 562486, 562487, C07C 4524, C07C 4966, C07C 5148, C07C 6316

Patent

active

042028280

ABSTRACT:
In a process for separation of naphthoquinone and phthalic acid from an aqueous slurry prepared by contacting a reaction mixture gas formed by a catalytic vapor phase oxidation of naphthalene with an aqueous medium, the decomposition of naphthoquinone is prevented and phthalic acid is substantially separated by adding a base to the aqueous slurry so as to neutralize only sulfuric acid component and maleic acid component without substantially neutralizing phthalic acid component and heating the aqueous slurry to dissolve phthalic acid to form a slurry of naphthoquinone in an aqueous solution of phthalic acid and extracting naphthoquinone with a solvent while preventing a crystallization of phthalic acid.
A pH of the aqueous slurry is adjusted in a range of 1.2 to 2.5 before the heat dissolution of phthalic acid and the extraction of naphthoquinone.
An aqueous phase obtained after the extraction of naphthoquinone is cooled to crystallize phthalic acid and then the filtrate separating from the resulting slurry is used as an aqueous medium for contacting with the reaction mixture gas, optionally after adjusting pH in a range of 1.2 to 2.5.

REFERENCES:
patent: 2536833 (1951-01-01), Bailey
patent: 2783251 (1957-02-01), Sayward
patent: 3379741 (1968-04-01), Tschamper et al.

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