3-Hydroxy-2-naphthoic acid → 3-Hydroxy-N-benzimidazolon-5-yl-2-naphthamide

Participants

Reaction Conditions

Reaction Steps

75.0 g (0.5 mol) of 5-aminobenzimidazolone and 41 g of anhydrous sodium acetate are initially introduced into 700 ml of N,N'-dimethylformamide and 776.8 g of 3-hydroxy-2-naphthoyl chloride (from 99.0 g (0.52 mol) of 3-hydroxy-2-naphthoic acid) in chlorobenzene are metered in at 5°-10° C. in the course of 30 min. After addition is complete, the mixture is subsequently stirred at 20° C. for 3 h, warmed to 50° C. and filtered. The filter cake does not filter off with suction very well (suction time: 14 h). For purification, the filter cake is taken up in 1 ml of methanol, the mixture is stirred and filtered off with suction, and the filter cake is washed with 250 ml of methanol and subsequently several times with a total of 1 l of boiling water. After drying, 130.3 g of 3-hydroxy-N-benzimidazolon-5-yl-2-naphthamide are obtained; this corresponds to 81.7% of theory.

Provenance & Evidence