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.