Hydrogen Peroxide → HCID 68130391, compound

Participants

Reaction Conditions

Reaction Steps

2-(Benzimidazolyl)amino-2-imidazoline dihydrochloride (prepared as described in Example 14) (27.4 g, 0.10 mol) was dissolved in concentrated hydrochloric acid (300 ml). The solution was stirred and heated to 80°C. A 15% solution of hydrogen peroxide (68 ml) was added dropwise to the stirred solution maintaining the temperature at 80°C. A colourless crystalline precipitate was soon deposited. At the end of the addition the solution was filtered, whilst hot and the precipitate washed with water and dried. This first crop (22.8 g), m.p. 275°-285°C, was found to be a mixture of chlorinated products. The second crop of crystals was deposited from the filtrate on cooling and was collected, washed with water and dried. This second crop (4.26g), m.p. 278°-281°C was found to be substantially pure 5,6-dichlorinated product. The first crop was recrystallised from aqueous dimethylformamide. The first (2.28 g), m.p. 297°-298°C, and second (6.42 g) m.p. 282°C crops of this recrystallisation were discarded, but the third crop (11.60 g) m.p. 252°-262°C was found to mainly 5,6-dichlorinated material. Both crops of 5,6-dichlorinated product were combined and recrystallised from boiling water to give 2-(5,6-dichlorobenzimidazolyl-2-imidazoline monohydrochloride (9.83 g; 29%) as colourless microcrystals m.p. 279°-281°C.

Provenance & Evidence