Crystal structure of 1,4-dieth­oxy-9,10-anthra­quinone

The asymmetric unit of the title compound, C(18)H(16)O(4), contains two crystallographically independent mol­ecules. The anthra­quinone ring systems are slightly bent with dihedral angles of 2.33 (8) and 13.31 (9)° between the two terminal benzene rings. In the crystal, the two independent mol­ecules adopt slipped-parallel π-overlap with an average inter­planar distance of 3.45 Å, forming a dimer; the centroid–centroid distances of the π–π inter­actions are 3.6659 (15)–3.8987 (15) Å. The mol­ecules are also linked by C—H⋯O inter­actions, forming a tape structure along the a-axis direction. The crystal packing is characterized by a dimer-herringbone pattern.