title: Two tautomeric forms of 2-amino-5,6-dimethylpyrimidin-4-one.
abstract: Derivatives of 4-hydroxypyrimidine are an important class of biomolecules. These compounds can undergo keto-enol tautomerization in solution, though a search of the Cambridge Structural Database shows a strong bias toward the 3H-keto tautomer in the solid state. Recrystallization of 2-amino-5,6-dimethyl-4-hydroxypyrimidine, C6H9N3O, from aqueous solution yielded triclinic crystals of the 1H-keto tautomer, denoted form (I). Though not apparent in the X-ray data, the IR spectrum suggests that small amounts of the 4-hydroxy tautomer are also present in the crystal. Monoclinic crystals of form (II), comprised of a 1:1 ratio of both the 1H-keto and the 3H-keto tautomers, were obtained from aqueous solutions containing uric acid. Forms (I) and (II) exhibit one-dimensional and three-dimensional hydrogen-bonding motifs, respectively.
authors.affiliation: Department of Chemistry, Georgetown University, 37th and O Sts NW, Washington, DC 20057, USA.
authors.forename: Victoria M
authors.initials: VM
authors.lastname: Hall
authors.affiliation: Department of Chemistry, Georgetown University, 37th and O Sts NW, Washington, DC 20057, USA.
authors.forename: Jeffery A
authors.initials: JA
authors.lastname: Bertke
authors.affiliation: Department of Chemistry, Georgetown University, 37th and O Sts NW, Washington, DC 20057, USA.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Swift
mesh_terms: D000586:Amination; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008745:Methylation; D008958:Models, Molecular; D011744:Pyrimidinones / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013237:Stereoisomerism
chemical_list: D011744:Pyrimidinones; C108140:4-hydroxypyrimidine
keywords: 4-hydroxypyrimidine; IR analysis; biomolecules; crystal structure; hydrogen-bonding motifs; pyrimidin-4-one; tautomerism