Crystal structure of 4-[4-(ethoxycarbonyl)piperazin-1-yl]benzoic acid

The asymmetric unit of the title compound, C14H18N2O4, contains two independent molecules (A and B) which have essentially the same conformation. The piperazine rings adopts chair conformations with the N atoms out of plane. The dihedral angles formed by the four approximately planar C atoms of the piperazine ring and the benzene ring is 30.8 (5)° in molecule A and 30.6 (5)° in molecule B. In the crystal, molecules A and B are connected by a pair of O—H...O hydrogen bonds, forming a dimer with graph-set notation R22(8). Weak C—H...O hydrogen bonds connect the dimers, forming zigzag chains along [001]