Redetermination of 2,6-dimethoxy­benzoic acid

The crystal structure of the title compound, C(9)H(10)O(4), was first reported by Swaminathan, Vimala & Lotter [Acta Cryst. (1976), B32, 1897–1900]. It has been re-examined, improving the precision of the derived geometric parameters. The asymmetric unit comprises a non-planar independent mol­ecule, as the meth­oxy substituents force the carb­oxy group to be twisted away from the plane of the aromatic ring by 56.12 (9)°. Due to the anti­planar conformation adopted by the OH group, the mol­ecular components do not form the conventional dimeric units, but are associated in the crystal in chains stabilized by linear O—H⋯O hydrogen bonds, involving the OH groups and the carbonyl O atoms, which form C(3) motifs.