Two tautomeric forms of 2‐amino‐5, 6‐dimethylpyrimidin‐4‐one. Issue 6 (6th May 2016)

• Record Type: Journal Article
• Authors: Hall, Victoria M.; Bertke, Jeffery A.; Swift, Jennifer A.
• Is Part Of: Acta crystallographica. Volume 72:Issue 6(2016)
• Page Start: 460
• Page End: 464
• Publication Date: 2016-05-06
• Subjects: tautomerism -- biomolecules -- pyrimidin‐4‐one -- crystal structure -- 4‐hydroxypyrimidine -- hydrogen‐bonding motifs -- IR analysis; Crystallography -- Periodicals; Crystals -- Periodicals; 548.3
• DOI: 10.1107/S2053229616007403
• Languages: English
• ISSNs: 2053-2296

Abstract

Abstract : Two tautomeric forms of 2‐amino‐5, 6‐dimethylpyrimidin‐4‐one were obtained under aqueous crystallization conditions. One form consists of only the 1 H ‐keto tautomer, while the other form has a 1:1 ratio of the 1 H ‐keto and 3 H ‐keto tautomers. 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 3 H ‐keto tautomer in the solid state. Recrystallization of 2‐amino‐5, 6‐dimethyl‐4‐hydroxypyrimidine, C6 H9 N3 O, from aqueous solution yielded triclinic crystals of the 1 H ‐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 1 H ‐keto and the 3 H ‐keto tautomers, were obtained from aqueous solutions containing uric acid. Forms (I) and (II) exhibit one‐dimensional and three‐dimensional hydrogen‐bonding motifs, respectively.