organic compounds
Crystal structures have been determined for the title compound in both its anhydrous, (I), C10H8O3, and monohydrate, (II), C10H8O3.H2O, forms. In (I), helical monoenantiomeric hydrogen-bonding (carboxyl-to-ketone) catemers, counteraligned with chains of the opposite chirality, pass through the cell in the b direction; a close contact of 2.57 Å is found between the sp2 carboxyl O atom and aromatic H6 atom on a neighboring molecule of the same chirality. The hydrate (II) displays a complex hydrogen-bonding pattern in which each water molecule participates in three hydrogen bonds to three different keto acid molecules. A 2.54 Å close contact is found between the ketone and aromatic H4 atom on a neighboring centrosymmetrically related molecule, as well as a 2.54 Å close contact between H1 and the ketone of a molecule of identical chirality translated one cell in the a direction.