Carbon Dioxide → 3-Hydroxy-2-naphthoic acid

Participants

Reaction Steps

A mixer 1 was fed hourly with 83 kg of sodium β-naphtholate, 130 g of light oil (boiling at 200°-310° C.) and 72 kg of β-naphthol, and they were dispersed and mixed. The dispersion was fed into a reactor 2 maintained at a carbon dioxide pressure of 3 kg/cm2.G at a rate of 285 kg/hr, and reacted at 270° C. The residence time was 4.5 hours. The reaction mixture which left the reactor 2 was cooled in a heat exchanger (not shown), and mixed with 420 liters/hr of water in the stirring tank 3. The temperature of the mixture was adjusted to 85° C., and the mixture was then fed into a separating tank 4 where it was separated at 85° C. into a light oil layer and an aqueous layer. The upper light oil layer was passed through a recovery device (not shown) to recover β-naphthol. The pH of the lower aqueous layer was adjusted to 5.5 with dilute sulfuric acid in a pH adjusting tank 5, and it was separated at 85° C. in a separating tank 6. By using a vacuum distillation device (not shown), β-naphthol was recovered from the separated lower tarry layer. The upper layer in the separating tank 6 was sent to a centrifugal extracting device 7 where it was extracted at 85° C. with 250 liters/hr of xylene. The xylene layer was sent to a recovery device (not shown) to recover β-naphthol. The aqueous layer in the extracting tank 7 was sent to an acid precipitation tank 8, and its pH was adjusted to 2.0 with dilute sulfuric acid at 85° C., followed by acid precipitation. Thus, 42.3 kg/hr of 2-hydroxynaphthalene-3-carboxylic acid (melting range 220°-221° C.; purity 99.5% β-naphthol content 0.03%) was obtained.

Provenance & Evidence