The interaction of n-glucono-1,54actone
with monovalent ions has been studied in aqueous solution at neutral pH. The o-gluconate salts of Lit, Naf, K+, NH:, Rb+, and Csc were studied by 13C NMR, PT'IR, and by X-ray powder diffraction. The spectroscopic evidence suggests that in aqueous solution, the alkali metal ions are hydrated, with no direct metal-sugar interaction. In the solid state, Li+ is four-coordinated, binding to two different gluconate anions through the carboxylate O-l and one of the acid anion OH groups, NaC binds to six oxygen atoms of six different acid anions. K+ is six-coordinated in the anhydrous salt, binding to four oxygen atoms of the four anion carboxylate groups and to two sugar OH groups; the monohydrated shows two different types of crystals (A and B). In the A crystal, K+ has eight-fold coordination, binding to six OH groups and two two HzO, with no direct metal-carboxylate interaction, while in the B crystal, the eight coordination around KC is completed by the acid anion carboxylate and OH groups as well as a water molecule. the Rb+ and K+ salts are isomorphous with and rather different from the Cs+ salt. The sugar intermolecular H-bonding network is rearranged upon acid ionization and salt formation.