2-Naphthol → 3-Hydroxy-2-naphthoic acid

Participants

Reaction Conditions

Reaction Steps

A stirred autoclave is charged with 1210 parts of β-naphthol, 620 parts of caustic soda solution (50% by weight strength) and 300 parts of 1,2-dinaphthoxyethane. As described in Example 4 the mixture is heated to an internal temperature of 260° C. while stirring and kept at this temperature for ten minutes. During this period the residual moisture is removed from the autoclave by applying 100 mm pressure. Dehydration is practically complete. Carbon dioxide is then introduced at the internal temperature of 260° C. up to a pressure of 7 atmospheres. After the absorption of carbon dioxide is completed the β-naphthol formed in the reaction is distilled off in vacuo. Further processing is carried out as in Example 5. 525 parts (72% of theory based on reacted β-naphthol) of 2-hydroxy-naphthalene-3-carboxylic acid is obtained with a melting point of 212° to 215° C.

Provenance & Evidence