Co-crystallised α- and β-Anomers of 2,3,4,6-Tetra-acetyl-d-glucopyranose, in which the α- and β-Anomers are Randomly Distributed in the Hydrogen-bonded Chains of Molecules

Abstract

A co-crystallised sample of α- and β-2,3,4,6-tetra-O-acetyl-d-glucopyranose [α:β = 1:2.86(8)], (α,β-1), has been isolated from a solution of 2,3,4,6-tetra-O-acetyl-d-glucopyranose in moist ethyl acetate/diethyl ether. In contrast, pure β-2,3,4,6-tetra-O-acetyl-d-glucopyranose, (β-1) was isolated on crystallisation from diethyl ethyl/petroleum ether. Species (α,β-1) is a solid solution in which approximately one in four of the molecules in the β-form is randomly substituted by a molecule of the α-anomer. The hydrogen bonded zig-zag chain connectivity of the pure β-anomer is maintained in the solid solution along the b direction. Since the parent d-glucopyranose compounds differ in their molecular packing and, therefore in structure, the solid solution phenonmenon in the case of their tetraacetyl derivatives is unexpected. Compound (β-1) and the (α,β-1) solid solution crystallize in the orthorhombic space group P212121: a = 7.8612(4) A, b = 10.2045(5) A, c = 20.7362(11) A, and Z = 4 for (β-1) at 120(2)K; and a = 7.9674(5) A, b = 10.2547(4) A, c = 21.1565(10) A, and Z = 4 for (α,β-1) at 291(2) K. Co-crystallised α- and β-Anomers of 2,3,4,6-Tetra-acetyl-d-glucopyranose, in which the α- and β-Anomers are Randomly Distributed in the Hydrogen-bonded Chains of Molecules Thomas C. Baddeley, William T. A. Harrison, R. Alan Howie, Janet M. S. Skakle and James L. Wardell α- and β-2,3,4,6-Tetra-O-acetyl-d-glucopyranose can form a crystalline solid solution in which a molecule of the β-form is randomly substituted by a molecule of the α-anomer Co-crystallised α- and β-Anomers of 2,3,4,6-Tetra-acetyl-d-glucopyranose, in which the α- and β-anomers are Randomly Distributed in the Hydrogen-bonded Chains of Molecules Thomas C. Baddeley, (1) William T. A Harrison, (1) R. Alan Howie, (1) Janet M. S. Skakle (1) and James L. Wardell (1,2)* (1) Department of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen, AB24 3UE, Scotland.