1-Piperazinecarboxylic acid, 4-(1H-benzimidazol-4-yl)-, ethyl ester, (Z)-2-butenedioate (1:1) 84806-83-7 Ethyl 4-(1H-benzimidazol-4-yl)-1-piperazinecarboxylate (Z)-2-butenedioate (1:1)