A mixture of 2-(4-aminophenyl)propionic acid (52.2 g), potassium ochlorobenzoate
(61.5 g), potassium carbonate (43.6 g) and copper powder
(0.3 g) in amyl alcohol (620 ml) is heating under reflux for 16 h. The major
proportion of the solvent is then removed by steam distillation. The residual
aqueous solution is treated with decolorising charcoal (20.0 g) and acidified
with 4 N sulfuric acid (220 ml). The cream product which crystallises is
dissolved in diethyl ether (500 ml).
The aqueous mother liquors are extracted with methylene chloride (900 ml).
The organic phases are combined, washed with water (800 ml) and dried over
anhydrous sodium sulfate. After filtration, the filtrate is concentrated to
dryness under a pressure of 20 mm Hg to give a semicrystalline paste (65.0
g) which is recrystallised from acetonitrile (550 ml). The crystals are filtered
off, and the product recovered (32.0 g) is recrystallised from acetonitrile (600
ml). There is thus obtained 2-[4-(2-carboxyphenyl)aminophenyl]propionic acid
(18.4 g) melting point 191°-192°C.
