Hydrochloric Acid → HCID 178527599, compound

Participants

Reaction Conditions

Reaction Steps

A round-bottom 3 neck flask was charged with 3,4-diaminobenzenesulfonic acid (8.0 g, 42.5 mmol) and anhydrous MeOH (0.85 L). O-Methyl-1,1,1-trichloroacetimidate was added (2.8 mL, 3.74 g, 21.2 mmol). The resultant suspension was stirred for 24 h at ambient conditions. Additional amount of O-methyl-1,1,1-trichloroacetimidate was added (1.4 mL, 1.87 g, 10.5 mmol) after this time, then reaction mixture was stirred for 72 h at ambient conditions, heated for 3 h at 50° C. and triethylamine (14 mL, 9.4 g, 93.5 mmol) was added. Stirring was continued at this temperature for 18 hours. Then reaction mixture was cooled to 30° C., and an intensive flow of dry HCl was passed through the solution until a precipitate was formed. The suspension was filtered off at 40° C., precipitate was washed with MeOH (4×150 mL, stirring of suspension for 10-15 min each turn) and with MeOH—HCl 3.5% solution (100 mL, 1 h of stirring). Product 1H,1′H-2,2′-bibenzimidazole-5,5′-disulfonic acid was pale yellow or colorless, weight 3.5 g, yield 42%. It may contain own hydrochloride as a salt. NMR 1H spectrum (Brucker Avance 300 instrument; solvent d6-dimethyl sulfoxide; δ, ppm; J, Hz): 5.27 br.s (—SO3H in exchange with H2O and NH) 7.73 m (2Ha, 2Hb), 8.01 br.s (2Hx). NMR 13C {1H} spectrum (Brucker Avance 300 instrument; solvent d6-dimethyl sulfoxide; δ, ppm): 113.00, 115.41, 123.27, 136.44, 137.60, 142.24, 145.34.

Provenance & Evidence