Carbon Dioxide → 6-Hydroxy-2-naphthoic acid

Participants

Reaction Conditions

Reaction Steps

A stainless steel pressure autoclave is charged with 100 parts of kerosene and 38 parts of potassium carbonate and heated to 280° C. It is then pressurized with 10 bar of carbon dioxide. Over the course of 5 hours, 50 parts of potassium β-naphtholate are metered in as a suspension in kerosene via a metering pump, part of the kerosene being distilled off, condensed and transferred out of the reaction vessel at reduced pressure. After cooling, the reaction mixture is taken up in water and the kerosene upper phase is decanted off. After acidification with sulfuric acid to a pH of 7, unreacted β-naphthol can be precipitated and separated off. Further acidification to pH 4 precipitates first the 2-hydroxynaphthalene-6-carboxylic acid and at pH 1 finally the remaining acids. The 2-hydroxynaphthalene-6-carboxylic acid is obtained in a yield of 67% based on potassium β-naphtholate used. In addition, 23% of unreacted β-naphtholate and small amounts of 2-hydroxynaphthalene-3-carboxylic acid and 2-hydroxynaphthalene-3,6-dicarboxylic acid are obtained.

Provenance & Evidence