To a solution of acetic acid (30 mL) containing 2-isopropylphenol (4.1 mL), 69% nitric acid (4 mL) was slowly added under ice bath conditions, keeping the reaction temperature constant with constant stirring for 30 minutes. Upon completion of the reaction, the reaction was quenched by the addition of ice water and subsequently extracted with tert-butyl methyl ether. The organic phase was washed sequentially with water and saturated saline, dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography, and the eluent was a mixed solvent of hexane/ethyl acetate in the ratio of 4:1, v/v. The target compound 2-isopropyl-4-nitrophenol (2.66 g, 49% yield) was finally obtained as a yellow solid. The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3): δ 1.3 (6H, d, J = 7.0 Hz), 3.25 (1H, m), 6.82 (1H, d, J = 9.0 Hz), 8.01 (1H, dd, J = 9.0, 2.5 Hz), 8.13 (1H, d, J = 2.5 Hz).
