A. Synthesis of 4-ethyl-3-nitrobenzoic acid
Nitric acid (12 mL) was added slowly and dropwise to a suspension of concentrated sulfuric acid (24 mL) of 4-ethylbenzoic acid (4.53 g, 30.16 mmol) at 0 °C. The reaction temperature was maintained at 0 °C with continuous stirring for 1.5 hours. Upon completion of the reaction, the mixture was carefully poured into ice water and a solid was precipitated. The solid product was collected by filtration and washed with cold water and dried to give 4-ethyl-3-nitrobenzoic acid (5.79 g, 98% yield).
Product characterization data: 1H NMR (400 MHz, DMSO-d6) δ 1.23 (3H, t, J = 7.2 Hz), 2.88 (2H, q, J = 7.2 Hz), 7.67 (1H, d, J = 8.0 Hz), 8.15 (1H, dd, J = 1.6, 8.0 Hz), 8.36 (1H, d, J = 1.6 Hz).
