Water → 3-Hydroxy-2-naphthoic acid

Participants

Reaction Steps

A mixer 1 was fed hourly with 83 kg of sodium β-naptholate, 181 kg of light oil (boiling at 200°-310° C.) and 57.2 kg of β-naphthol, and they were mixed and dispersed. About one-third of the light oil layer (upper layer) formed in the separating tank was removed, and fed into a recovery apparatus (not shown) to recover the dissolved β-naphthol and a tiny amount of sodium β-naphtholate as an aqueous solution of sodium β-naphtholate. The mixture remaining in the separating tank 2 consisted of 81 kg of sodium β-naphtholate, 42.4 kg of β-naphthol and 130 kg of light oil. The liquid mixture was fed into a reactor 3 at a rate of 253.4 kg per hour, and reacted with carbon dioxide at a pressure of 5 kg/cm2.G and a temperature of 250° C. The residence time was 5 hours. The reaction mixture which left the reaction tank 3 was cooled in a heat exchanger (not shown), and mixed with 400 liters/hour of water in a stirring tank 4, and sent to a separating tank 5 where the mixture was separated at 85° C. into a light oil layer and an aqueous layer. From the upper light oil layer, β-naphthol was recovered by using a recovery device (not shown). The lower aqueous layer was sent to a pH adjusting tank 6, and after adjusting its pH to 5.5 with dilute sulfuric acid, was introduced into a separating tank 7. From the lower tarry layer in the separating tank 7, β-naphthol was recovered by using a vacuum distillation device (not shown). The upper layer was sent to an extracting device 8 where it was extracted with 250 liters/hr of xylene at 80° C. The xylene layer was sent to a recovery device (not shown) to recover β-naphthol. The aqueous layer in the extracting tank 8 was sent to an acid precipitation tank 9 where it was subjected to acid precipitation at a pH of 2.0 using dilute sulfuric acid at 85° C. Thus, 41.3 kg/hr of 2-hydroxynaphthalene-3-carboxylic acid (melting range 220°-221° C.) was obtained.

Provenance & Evidence