Vitamin B1-catalyzed one-pot ultrasound-assisted synthesis of 1,2-disubstituted benzimidazole and its selective recognition of metal ions.

An efficient one-pot synthesis of 1,2-disubstituted benzimidazoles was developed via cyclocondensation starting from o-phenylenediamine with substituted aromatic aldehydes using catalyst vitamin B1 under ultrasound-assisted, and was characterized by HR-MS, FT-IR, 1H and 13C NMR spectroscopy. N-Ts-substituted 1,2-disubstituted benzimidazoles were formed when 2 equivalents of p-toluenesulfonic acid were added to the reaction. The reaction conditions of the method are environmentally friendly, no metal is required, the operation is simple, the substrates are extensive, the yield is high, and the catalyst is non-toxic and reusable. The crystal structure of compound 1-(2-methoxybenzyl)-2-(2-methoxyphenyl)-1H-benzoimidazole (3ab) in triclinic P21/n space group is presented. 4-(1-(2,3,4-Trihydroxybenzyl)-1H-benzoimidazol-2- yl)benzene-1,2,3-triol (3af) as a metal ion fluorescent probe, has excellent selectivity to Pb2+ and Ag+, and exhibits obvious discoloration. An efficient one-pot synthesis of 1,2-disubstituted benzimidazoles was developed via cyclocondensation starting from o-phenylenediamine with substituted aromatic aldehydes using catalyst vitamin B1 under ultrasound-assisted, and were characterized by HR-MS, FT-IR, 1H and 13C NMR spectroscopy. N-Ts-substituted 1,2-disubstituted benzimidazoles were formed when 2 equivalents of p-toluenesulfonic acid was added to the reaction. The crystal structure of compound 1-(2-methoxybenzyl)-2-(2-methoxyphenyl)-1H-benzoimidazole (3ab) in triclinic P21/n space group was presented. [ABSTRACT FROM AUTHOR]