Sodium Hydroxide → 3-{3-[4-(diphenylmethyl)-1-piperazinyl]-propyl}-2,3-dihydro-2-oxo-1H-benzimidazole-1-acetic acid hemihydrate

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Reaction Steps

A mixture of 9.8 parts of ethyl 3-{3 -[4-(diphenylmethyl)1-piperazinyl]propyl}-2,3-dihydro-2-oxo-1H-benzimidazole-1-acetate, 1.2 parts of sodium hydroxide and 150 parts of water is stirred and refluxed for 5 minutes (+80° C.). The reaction mixture is filtered and the filtrate is acidified with acetic acid to pH 5.8-6: a sticky precipitate is formed. It is separated and crystallized from ethanol and water. The product is filtered off and dried in vacuo at 100° C. for 3 hours, yielding 6 parts of 3-{3-[4-(diphenylmethyl)-1-piperazinyl]propyl}-2,3-dihydro-2-oxo-1H-benzimidazole-1-acetic acid hemihydrate; mp. 138.7° C.

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