3.2.1. Synthesis of 2-(chloromethyl)-1H-Benzimidazole (2)

A mixture of ortho-phenylene diamine (1.0 g, 9.25 mmol) and chloroacetic acid (1.32 g, 13.97 mmol) in 4 N HCl (60 mL) was refluxed for 24 h. The purified product was obtained by re-crystallization from water after neutralization with 6 N NH₄OH, yield 0.4 g (40%). The product was used in the following step without further purification [63]. M.p. 149–151 °C (Lit. 147.8–148.2 °C). ¹H NMR (DMSO-d₆): δ 4.91 (s, 2H, CH₂), 7.25–7.29 (m, 2H, CH, Ar), and 7.57–7.59 (m, 2H, CH, Ar).