Sodium Hydroxide → 5-Chloro-1,3-dihydro-1-(4-piperidinyl)-2H-benzimidazol-2-one

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Reaction Steps

A mixture of 22.3 g of 1-carbethoxy-4-(5-chlorobenzimidazol-2-on-1-yl)-piperidine, 13 g of 50% strength sodium hydroxide solution and 90 ml of water was boiled under reflux for 24 hours. After the mixture had been cooled, the solution was stirred with 8.5 g of ammonium chloride for 30 minutes and extracted with chloroform, and the undissolved material was filtered off and discarded. The chloroform solution was dried and evaporated. The product crystallized, and has a melting point of 220° C.

Provenance & Evidence