General procedure for the synthesis of 1-naphthylhydrazine from methyl 1-naphthalenecarboxylate: Methyl 1-naphthalenecarboxylate (0.52 g, 2.8 mmol) was dissolved in 15 mL of 98% hydrazine hydrate, fitted with an air condenser tube, and the reaction was stirred for 8 h at 110 °C. The reaction was carried out in the presence of an air condenser tube. Upon completion of the reaction, the mixture was cooled to room temperature and the precipitated crystalline solid was collected by filtration. The resulting solid was dissolved in ethyl acetate (EtOAc), and the organic phase was washed sequentially with water, saturated sodium bicarbonate (NaHCO3) solution and brine, and then concentrated under reduced pressure to remove the solvent. The product was purified by column chromatography (elution gradient: hexane/ethyl acetate 1:1; hexane/ethyl acetate 1:2) to give 0.38 g (73% yield) of white crystalline solid. Thin layer chromatography (TLC) Rf = 0.53 (unfolding agent: chloroform/methanol 10:1). Melting point 166-169 °C (literature value 166 °C).IR (KBr, cm-1): νmax 3280 (N-H), 1658 (C=O), 1606, 1588, 1524, 1261, 955.1H NMR (300 MHz, DMSO-d6): δ 9.69 (s, 1H, NH), 8.35-8.10 (m. 1H, Ar-H), 8.05-7.88 (m, 2H, Ar-H), 7.63-7.26 (m, 4H, Ar-H), 4.60 (s, 2H, NH2).13C NMR (75 MHz, DMSO-d6): δ 168.2 (C=O), 133.6, 133.3, 130.2, 130.1, 128.4, 128.4 126.8, 126.4, 125.6, 125.6, 125.2 (Ar-C).
