1,2-Diphenoxyethane → 3-Hydroxy-2-naphthoic acid

Participants

Reaction Conditions

Reaction Steps

A stirred autoclave is charged with 1220 parts of β-naphthol, 620 parts of caustic soda solution (50% by weight strength) and 360 parts of 1,2-diphenoxyethane. The mixture is heated while stirring to an internal temperature of 260° C. and kept at this temperature for ten minutes as in Example 4. Residual moisture is removed from the autoclave within five minutes at 100 mm pressure; dehydration is practically complete. Carbon dioxide is then passed into the autoclave at an internal temperature of 260° C. up to a pressure of 7 atmospheres. Carboxylation followed by processing are carried out as in Example 4. The mixture of organic phase and aqueous phase is acidified to about pH 5 at a temperature of 95° C. with vigorous stirring and the β-naphthol liberated is separated with the organic phase. The clear aqueous phase is heated to 85° to 90° C., acidified to pH about 3 with hydrochloric acid and stirred for another thirty minutes. After cooling to 50° C. the yellowish crystals of 2-hydroxy-naphthalene-3-carboxylic acid are suction filtered and dried at 70° C. in vacuo. 550 parts (75.5% of theory based on reacted β-naphthol) of 2-hydroxynaphthalene-3-carboxylic acid is obtained with a melting point of 214° to 216° C.

Provenance & Evidence