Ethanol → 3-Oxo-N-(2-oxo-2H-benzo[d]imidazol-5-yl)butanamide

Participants

Reaction Conditions

Reaction Steps

An 82° C. solution of 2.86 kg (19.2 mol) of 5-amino-2-benzimidazolone and 24 kg of ethanol containing 50% by weight of water is metered per hour continuously and simultaneously with 2.06 kg (24 mol) of diketene (purity 98%) into a reactor equipped with a stirrer, reflux condenser, thermometer and, at the bottom, with a run-off. The light-colored suspension in the reactor is refluxed at about 85° C. with stirring and is kept to a constant volume of about 0.3 l by pumping out. The removed suspension is cooled down to about 15° C., and the light-colored crystals are separated by filtration from 22 kg per hour of mother liquor, washed with on average 6 kg per hour of 50% strength ethanol and dried, leaving 4.03 kg (17.3 mol) per hour of 5-acetoacetylamino-2-benzimidazolone as a virtually white crystalline powder. The yield based on amine is 90%.

Provenance & Evidence