Carbon Dioxide → 3-Hydroxy-2-naphthoic acid

Participants

Reaction Conditions

Reaction Steps

A reactor was charged with 75 kg/hr of β-naphthol, 30 kg/hr of diisopropyltoluene and 30 kg/hr of a 45% aqueous sodium hydroxide solution for performing the formation of an alkali metal salt of β-naphthol and primary dehydration in a nitrogen atmosphere at 180° C. (residence time: 2 hr). The reaction mixture was fed to the second reactor at a rate of 119 kg/hr where it was subjected to reaction for the formation of an alkali metal salt of β-naphthol and secondary dehydration in a nitrogen atmosphere at 230° C. (residence time: 1 hr). A homogeneous liquid mixture (salt mass) in the second reactor was sent to a carboxylation reactor at a rate of 112 kg per hour where it was reacted with carbon dioxide at 260° C. at a CO2 pressure of 5 kg/cm2G (residence time: 2 hr). The reaction mixture was cooled through a heat exchanger and sent to a primary extraction tank where it was mixed with 200 l/hr of water, 306 kg/hr of diisopropyltoluene layer from a secondary extraction tank and 70% sulfuric acid to adjust its pH to 6.0 at a controlled temperature of 90° C. (residence time: 0.5 hr). The mixture was sent to a separation tank where it was separated into the diisopropyltoluene layer and the aqueous layer at 90° C. The upper diisopropyltoluene layer was freed of β-naphthol by a recovery device. The lower aqueous layer was supplied to the secondary extraction tank where it was mixed with 300 kg of diisopropyltoluene per hour at 90° C. (residence time: 0.5 hr). The mixture was then supplied to a separation tank where it was separated into the diisopropyltoluene layer and the aqueous layer at 85° C. The upper diisopropyltoluene layer was returned to the primary extraction tank and the lower aqueous layer was transferred to an acid precipitation tank where it was adjusted to a pH of 2.0 with dilute sulfuric acid at 85° C. The resulting precipitate was filtered under heat at 85° C. to give 27.8 kg/hr of 2-hydroxynaphthalene-3-carboxylic acid (99% purity and β-naphthol content of 0.1%). The yield of 2-hydroxynaphthalene-3-carboxylic acid was 43.8% based on the sodium salt of β-naphthol and 88.5% based on β-naphthol consumed. The β-naphthol recovered was 50.9 kg per hour.

Provenance & Evidence