Complex formation between aqueous zinc chloride and cellulose-related d-glucopyranosides

Measurements of n.m.r. chemical shifts, and the method of continuous variations by using measurements of optical rotation, indicate that zinc chloride forms complexes with vicinal hydroxyl groups of several d-glucopyranosides. I.r. and u.v. spectra of aqueous mixtures of zinc chloride and methyl β-d-glucopyranoside illustrate that the concentration and stability of this complex increases as the concentration of zinc chloride is increased. The effect of concentration of zinc chloride on the complexing with methyl β-d-glucopyranoside parallels the swelling and loss of crystallinity of cellulose, indicating that the swelling mechanism for cellulose in aqueous zinc chloride solutions depends on the formation of a complex with the vicinal hydroxyl groups on C-2 and C-3 of the d-glucopyranoside repeating unit.