Hydrochloric Acid → 4-(2-Oxopyrrolidin-1-yl)benzoic acid

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Reaction Conditions

Reaction Steps

4-Aminobenzoic acid (100 g, 0.73 mol) is suspended in water (400 mL) and toluene (200 mL), and thereto is added dropwise 30% aqueous sodium hydroxide solution (97 g, 0.73 mol) under ice-cooling. After confirming that pH is basic enough, 4-chlorobutyric chloride (103 g, 0.73 mol) and 30% aqueous sodium hydroxide solution (290 g, 2.2 mol) are added dropwise simultaneously while maintaining the pH range of 9-12 and temperature range of 15-20° C. over 1 hour. After stirring at room temperature for 1 hour, sodium hydroxide (88 g, 2.2 mol) is added to the mixture under ice-cooling. To the reaction solution is added conc. hydrochloric acid (370 g) at 30° C. or below and precipitated crystals are collected by filtration. The resulting crystals are washed with water and air-dried at 40° C. to give 4-(2-pyrrolidon-1-yl)benzoic acid (144 g, yield: 96.0%, purity: 98.3%). The purity was determined by HPLC analysis.

Provenance & Evidence