The asymmetric unit of the title compound, C(16)H(16)N(2)O(4), contains one half-mol-ecule, the whole mol-ecule being generated by an inversion center located at the mid-point of the C-C bond of the central ethane group. An intra-molecular O-H⋯O hydrogen bond forms an S(6) ring motif. In the crystal, mol-ecules are connected via N-H⋯O hydrogen bonds, generating infinite chains along [1-10].