GENERAL METHOD: Benzoic acid (0.353 g, 2.89 mmol) was dissolved in 50 mL of anhydrous tetrahydrofuran (THF) and N-hydroxysuccinimide (0.40 g, 3.47 mmol) and N,N'-dicyclohexylcarbodiimide (DCC, 0.776 g, 3.76 mmol) were added in sequence. The reaction mixture was stirred at room temperature for 48 hours. Upon completion of the reaction, the insoluble by-product N,N'-dicyclohexylurea (DCU) was removed by filtration and the filtrate was concentrated under reduced pressure to remove the solvent. The concentrated residue was dissolved in chloroform (CHCl3), the organic phase was dried with anhydrous sodium sulfate (Na2SO4), filtered and the solvent was evaporated to dryness under reduced pressure. The crude product was purified by silica gel column chromatography with the eluent being a hexane solution of 40% ethyl acetate to give the white solid product N-hydroxysuccinimide ester benzoate (0.586 g, 93% yield). To improve the purity of the product, the resulting white solid was recrystallized in 2-propanol.
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