2.2.4. Synthesis of 3,5-Dimethyl-4-(4′-Nitrophenyl)-1H-Pyrazole (P2)

Hydrazine hydrate (1.7 mmol, 0.08 mg) was added to a mixture of D2 (1.4 mmol, 0.3 g) in ethanol (10 mL) at room temperature. Then, the mixture was heated under reflux for 2 h. The reaction mixture was evaporated under reduced pressure and the residue was purified by recrystallization in ethanol to give a white solid (yield: 230 mg, 76%; ¹H NMR (400 MHz, CDCl₃) δ/ppm 8.29–8.27 (m, 2H), 7.45–7.42 (m, 2H), 2.35 (s, 6H). ¹³C NMR (100 MHz, CDCl₃): δ/ppm 141.0, 135.6, 129.5, 123.8, 11.8. MS (MALDI+, dithranol) m/z: 218.0 [M + H]+. Anal. Found C, 60.40; H, 5.00; N, 19.21. Calc for [C₁₁H₁₁N₃O₂]: C, 60.82; H, 5.10; N, 19.34%. FTIR ν/cm⁻¹ 3174 (N-H), 1596, 1515 (NO₂), 1342 (NO₂)).