Gallic acid

Abstract

Anhydrous 3,4,5-trihydroxybenzoic acid, C7H6O 5, is essentially planar, with its non-H atoms exhibiting mean and maximum deviations from coplanarity of 0.014 and 0.0377 (5) Å, respectively. The C -C -C -OH torsion angle about the bond linking the carboxyl group to the benzene ring is -0.33 (10)°. In the crystal, the -COOH groups form centrosymmetric hydrogenbonded cyclic dimers [graph set R 2 2(8)] and the phenolic -OH groups participate in both intra-and intermolecular hydrogen bonds, forming a threedimensional network structure.