title: Solid-state transformation of 4, 2'-anhydro-5-(beta-D-arabinofuranosyl)uracil dihydrate to 4, 2'-anhydro-5-(beta-D-arabinofuranosyl)uracil monohydrate.
abstract: Crystals of 4,2'-anhydro-5-(beta-D-arabinofuranosyl)uracil, (I), obtained from an aqueous solution, were characterized as the dihydrate, C(9)H(10)N(2)O(5).2H(2)O, (Ia). In air, these crystals slowly transform to the monohydrate, C(9)H(10)N(2)O(5).H(2)O, (Ib), but remain crystalline. The solid-state transformation proceeds with the loss of one water molecule and a rearrangement of hydrogen-bonded layers of molecules. The furanose ring in (I) has an approximate C4'-exo,O4'-endo twist conformation. The central five-membered ring is slightly puckered. The uracil group is planar within experimental uncertainty.
authors.affiliation: Institut für Organische Chemie, Universität Frankfurt, Marie-Curie-Strasse 11, D-60439 Frankfurt am Main, Germany. bats@indy2.org.chemie.uni-frankfurt.de
authors.forename: J W
authors.initials: JW
authors.lastname: Bats
authors.forename: U
authors.initials: U
authors.lastname: Parsch
authors.forename: J W
authors.initials: JW
authors.lastname: Engels
mesh_terms: D001086:Arabinofuranosyluracil / Q000031:analogs & derivatives* / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006575:Heterocyclic Compounds, 3-Ring / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D014498:Uracil / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: C414938:4,2'-anhydro-5-arabinofuranosyluracil; D006575:Heterocyclic Compounds, 3-Ring; D001086:Arabinofuranosyluracil; D014498:Uracil