Hydrochloric Acid → 1,3-dihydro-1-(3-hydroxypropyl)-2H-benzimidazol-2-one hydrate

Participants

Reaction Steps

A solution of 180 parts of 3-[(2-nitrophenyl)amino]-1-propanol in 200 parts of methanol and 100 parts of a hydrochloric acid solution 10N is hydrogenated at normal pressure and at a temperature at 50° C, in the presence of 5 parts of palladium-on-charcoal catalyst 10%. After the calculated amount of hydrogen (3 moles) is taken up, hydrogenation is stopped. The catalyst is filtered off and the filtrate is evaporated. The residue (mainly 3-[(2-aminophenyl)amino]-1-propanol hydrochloride) is dissolved in 500 parts of water. To this solution is added a solution of 88.8 parts of potassium isocyanate in 150 parts of water and the whole is stirred and refluxed for 15 hours. The reaction mixture is cooled and the product is extracted with trichloromethane. The extract is dried and evaporated. The residue is dissolved in 250 parts of boiling water, treated with activated charcoal and crystallized at room temperature. The precipitate is filtered off and recrystallized from 400 parts of water, followed by recrystallization from ethyl acetate, yielding 58 parts of 1,3-dihydro-1-(3-hydroxypropyl)-2H-benzimidazol-2-one hydrate; mp. 48°-65° C.

Provenance & Evidence