(1E,2E)-N1,N2-bis(2,6-bis(diphenylmethyl)-4-methylphenyl)ethane-1,2-diimine (6.14 g, 6.81 mmol) in THF (235 mL) was added to paraformaldehyde (204 mg, 6.81 mmol), anhydrous zinc chloride (928 mg, 6.81 mmol) at 70 °C. After that, HCl in dioxane (4 M, 2.56 mL,10.2 mmol) was added dropwise. After 5 h, at 70 °C, the mixture was concentrated under reduced pressure followed by flash column chromatography over silica gel with CH2Cl2-MeOH (9:1) to give the pale pink solid, which was further purified recrystallization (CH2Cl2-n-hexane) gave 1,3-Bis(2,6-dibenzhydryl-4-methylphenyl)-1H-imidazol-3-ium chloride.
