title: Methyl tetra-O-acetyl-α-D-glucopyranuronate: crystal structure and influence on the crystallisation of the β anomer.
abstract: Methyl tetra-O-acetyl-β-D-glucopyranuronate (1) and methyl tetra-O-acetyl-α-D-glucopyranuronate (3) were isolated as crystalline solids and their crystal structures were obtained. That of the β anomer (1) was the same as that reported by Root et al., while anomer (3) was found to crystallise in the orthorhombic space group P212121 with two independent molecules in the asymmetric unit. No other crystal forms were found for either compound upon recrystallisation from a range of solvents. The α anomer (3) was found to be an impurity in initially precipitated batches of β-anomer (1) in quantities <3%; however, it was possible to remove the α impurity either by recrystallisation or by efficient washing, i.e. the α anomer is not incorporated inside the β anomer crystals. The β anomer (1) was found to grow as prisms or needles elongated in the a crystallographic direction in the absence of the α impurity, while the presence of the α anomer (3) enhanced this elongation.
authors.affiliation: Department of Chemistry/Analytical and Biological Chemistry Research Facility/Synthesis and Solid-state Pharmaceutical Centre, University College Cork, College Road, Cork, Ireland.
authors.forename: John A
authors.initials: JA
authors.lastname: Hayes
authors.affiliation: Department of Chemistry/Analytical and Biological Chemistry Research Facility/Synthesis and Solid-state Pharmaceutical Centre, University College Cork, College Road, Cork, Ireland.
authors.forename: Kevin S
authors.initials: KS
authors.lastname: Eccles
authors.affiliation: Department of Chemistry/Analytical and Biological Chemistry Research Facility/Synthesis and Solid-state Pharmaceutical Centre, University College Cork, College Road, Cork, Ireland.
authors.forename: Simon E
authors.initials: SE
authors.lastname: Lawrence
authors.affiliation: Department of Chemistry/Analytical and Biological Chemistry Research Facility/Synthesis and Solid-state Pharmaceutical Centre, University College Cork, College Road, Cork, Ireland. Electronic address: h.moynihan@ucc.ie.
authors.forename: Humphrey A
authors.initials: HA
authors.lastname: Moynihan
mesh_terms: D000107:Acetylation; D002236:Carbohydrate Conformation; D003460:Crystallization; D018360:Crystallography, X-Ray; D005965:Glucuronates / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry*; D008958:Models, Molecular
chemical_list: D005965:Glucuronates; D007783:Lactones
keywords: Crystallisation of anomers; Methyl tetra-O-acetyl-d-glucopyranuronate