Carbon Dioxide → 3-Hydroxy-2-naphthoic acid

Participants

Reaction Steps

A finishing treatment was carried out continuously, while employing the facilities as shown in the drawing. On an hourly basis, 83 kg of sodium 2-naphtholate, 42 kg of 2-naphthol and 166 kg of a mixture of hydrogenated triphenyls were fed to a stirring tank 1, followed by stirring and suspension. The resulting suspension mixture was supplied at a rate of 291 kg/hr to a reaction vessel 2 maintained at a carbon dioxide pressure of 6 kg/cm2 (G), and a reaction was allowed to proceed at 260° C., with the residence time being kept at 3 hours. The reaction mixture flowing out of the reaction vessel 2 was cooled with a heat exchanger 3, and mixed with water fed at a rate of 420 1/hr in a stirring tank 4, and the resulting mixture was regulated at a temperature of 85° C. and transferred to a separating tank 5, followed by separation into the reaction medium layer and the water layer at 85° C. From the upper reaction medium layer, the 2-naphthol was recovered as sodium naphtholate with use of a recovery apparatus (not shown in the drawing). The lower water layer was adjusted in a pH adjusting tank 6 to a pH 5.5 with dilute sulfuric acid and transferred to an extractor 7, where the 2-naphthol and tar were extracted with 2000 liters of xylene. From the xylene layer, there were recovered the xylene and 2-naphthol by use of a vacuum distillation apparatus (not shown in the drawing). The water layer flowing out of the extactor 7 was transferred to an acid precipitation tank 8, and adjusted to a pH 2.0 with dilute sulfuric acid at 85° C. to perform acid precipitation, whereby there was produced 2-hydroxynaphthalene-3-carboxylic acid at a rate of 44.8 kg/hr. The yield based on sodium 2-naphtholate was 47.7%, and 2-naphthol was recovered at a rate of 37.3 kg/hr, with the selectivity being 99.4%.

Provenance & Evidence