4-(Aminomethyl)benzoic acid (302 mg, 2.00 mmol) was dissolved in methanol (30 mL) and thionyl chloride (1.16 mL, 16.0 mmol) was added slowly and dropwise at room temperature. The reaction mixture was stirred at room temperature overnight. Subsequently, the solvent was removed by distillation under reduced pressure to afford the target product, methyl 4-aminomethylbenzoate hydrochloride (15d), as a colorless solid in 390 mg (97%) yield with a melting point of 234 °C. The molecular formula was C9H12ClNO2 (molecular weight 201.7). Thin layer chromatography (TLC) analysis showed an Rf value of 0.22 (Expanding agent: ethyl acetate/1% diethylmethylamine, detection wavelength 254 nm). Nuclear magnetic resonance hydrogen spectroscopy (1H NMR, 400 MHz, DMSO-D6) showed chemical shifts δ [ppm]: 3.86 (single peak, 3H, CO2CH3), 4.10 (single peak, 2H, H3NCH2), 7.63-7.67 (multiple peaks, 2H, 3-HB, 5-HB), 7.96-8.01 (multiple peaks, 2H, 2-HB, 6 -HB), 8.61 (broad peaks, 3H, NH3). Nuclear magnetic resonance carbon spectra (13C NMR, 101 MHz, DMSO-D6) showed chemical shifts δ [ppm]: 41.7 (1C, H3NCH2), 52.2 (1C, CO2CH3), 129.2 (2C, C-3B, C-5B), 129.3 (2C, C-2B, C-6B), 129.5 (1C, C-1B). 139.4 (1C, C-4B), 165.9 (1C, CO2CH3). Fourier transform infrared spectroscopy (FT-IR) showed absorption peaks ν [cm-1]: 2963 (NH3+), 2878 (C-H aliphatic), 2573 (NH3+), 1678 (C=O), 1597, 1578, 1477 (C=C aromatic), and 864 (aromatic ring out-of-plane bending vibration). High resolution mass spectrometry (HRMS, APCI) showed m/z = 166.0865 (calculated value C9H12NO2 [M+H]+: 166.0863). High performance liquid chromatography (HPLC) analysis showed retention time tR = 6.4 min and purity 99.9%.
