Crystal structure of isopropyl 2-hydroxy-2-phenylacetate: a pharmacopoeia reference standard

The title compound, C 11 H 14 O 3 , is used as a pharmacopoeia reference standard for determining impurities in the drug Pregabalin, used for the treatment of epilepsy and diabetic neuropathic pain. The molecule is far from being planar, with the dihedral angle between the planes of the aromatic ring and the carboxyl fragment (O—C=O) being 76.1 (6)°. The isopropyl substituent is located in a synperiplanar position relative to the C=O bond and is turned so that the C—O—C—H torsion angle is −43.7°. In the crystal, bifurcated O—H...(O,O) hydrogen bonds, enclosing R 1 2 (5) ring motifs, lead to the formation of chains propagating along the c -axis direction. Inversion-related chains are linked by the C—H...O hydrogen bonds, forming undulating layers lying parallel to the bc plane.