反应详情

A solution of 5 g (16.7 mmole) of 2-[p-carboxyphenyl]-5,6-dinitrobenzimidazole (as prepared in Example I) in 200 ml of methanol at 0° C was thoroughly purged with nitrogen. To this was added 500 mg of 10% palladium on charcoal, and 30 ml of concentrated HCl. The hydrogenation flask was then pressurized with 55 lbs/in2 of hydrogen, and the flask was shaken at room temperature for 8 hours. After the reaction period had elapsed, the solution was filtered by suction, and the filtrate evaporated to dryness in vacuo. The residual yellow solid was redissolved in a minimum amount of boiling methanol (which contained a trace of HCl), and the filtered solution added to 50 ml of concentrated HCl. Removal of the methanol from the solution in vacuo and subsequent cooling in ice yielded 4.2 g (82%) of 2-[p-carboxyphenyl]-5,6-diaminobenzimidazole hydrochloride as fluffy yellow needles.

1. customAfter the reaction period
2. filtrationthe solution was filtered by suction
3. customthe filtrate evaporated to dryness in vacuo
4. dissolutionThe residual yellow solid was redissolved in a minimum amount of boiling methanol (which
5. additionadded to 50 ml of concentrated HCl
6. customRemoval of the methanol from the solution in vacuo
7. temperaturesubsequent cooling in ice