51688-75-6

34921-76-1

51688-75-6

Preparation of 4-amino-3-ethylbenzoic acid: N1-(4-cyano-2-ethylphenyl)acetamide (10.1 g, 53.66 mmol) was suspended in 20% aqueous sodium hydroxide (38 mL, 188 mmol) and stirred at reflux for 22 h under nitrogen protection. Upon completion of the reaction, the dark-colored reaction solution was cooled to room temperature, diluted with water (200 mL), and washed with ethyl acetate (2 × 50 mL). The aqueous phase was adjusted to pH 5 with concentrated hydrochloric acid and subsequently extracted with ethyl acetate (2 x 100 mL). The aqueous phase was continued to be adjusted to pH 4 with concentrated hydrochloric acid and again extracted with ethyl acetate (2 × 50 mL). All organic phases were combined, washed with saturated saline (50 mL), dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residual solid was ground with petroleum ether, filtered, and the filter cake was washed with petroleum ether and dried in vacuum to obtain a beige solid 4-amino-3-ethylbenzoic acid (7.49 g, 84.5% yield) with good purity.