How is 1,3-Dimethyl-1H-benzimidazol-3-ium iodide (CAS: 7181-87-5) typically synthesized?

1,3-Dimethyl-1H-benzimidazol-3-ium iodide (CAS: 7181-87-5) is commonly synthesized via the reaction of 1,3-dimethylbenzimidazole with iodine in the presence of a base like potassium carbonate. The yield is around 70-80%, and the reaction is typically carried out in an aprotic solvent such as N,N-dimethylformamide (DMF). The use of a catalyst is not typically necessary, but it enhances selectivity and improves yield.