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

The asymmetric unit of the title compound, C(14)H(18)N(2)O(4), 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 R (2) (2)(8). Weak C—H⋯O hydrogen bonds connect the dimers, forming zigzag chains along [001].