A substituted EDOT precursor: diethyl 3,4‐di­hydroxy­thio­phene‐2,5‐di­carboxyl­ate

The title compound, C₁₀H₁₂O₆S, has been obtained as dark‐yellow chunk‐shaped crystals, together with the expected thin white needles. The structures of the two phases are identical. Two independent mol­ecules compose the asymmetric unit: one mol­ecule is totally planar, whereas a methyl group of the second mol­ecule points out of the plane. Each mol­ecule participates in several intra‐ and intermolecular hydrogen bonds and short contacts. The overall structure can be regarded as parallel sheets of mol­ecules. Within a sheet, mol­ecules are connected to one another in an infinite network via numerous short intermolecular contacts. Sheets are connected via hydrogen bonds and short contacts, in particular involving the methyl groups.