Polymorphism of a Simple Organic Amide

Glycolanilide (2-hydroxy-N-phenylacetamide), a simple amide, may be reproducibly crystallized in either of two polymorphic forms. The crystal and molecular structures of each polymorph have been determined, revealing that the two polymorphs differ in the extent and arrangement of intermolecular hydrogen bonding. The more stable polymorph displays one-dimensional chains linked through hydrogen bonds between the amide carbonyl and the α-hydroxyl group. In the metastable polymorph, analogous chain structures are overlain with cyclic hydrogen-bonded amide dimers, with an additional set of hydrogen bonding contacts joining the chain and cyclic motifs.