(E)-3,4-Dihydroxy­benzaldehyde 4-ethyl­thio­semicarbazone

The title compound, C(10)H(13)N(3)O(2)S, was prepared by condensation of 3,4-dihydroxy­benzaldehyde with 4-ethyl-3-thio­semicarbazide. The mol­ecule adopts an E configuration with respect to the C=N bond. One of the OH substituents on the dihydroxy­benzene ring is disordered over the two possible 3-positions on either side of the ordered 4-hydr­oxy group. The occupancy of the major disorder component refined to 0.633 (7). The mol­ecule is essentially planar, with an r.m.s. deviation through all non-H atoms of 0.0862 Å. An intra­molecular N—H⋯N hydrogen bond forms between the outer amine residue and the imine N atom, generating an S(5) ring motif and contributing to the planarity of the mol­ecule. In the crystal structure, an extensive network of classical O—H⋯O, O—H⋯S and N—H⋯S hydrogen bonds and weak C—H⋯O and S⋯O [3.301 (3) Å] inter­actions link mol­ecules into sheets running approximately parallel to the ab plane.