Complexes of carbohydrates with metal cations. I. Determination of the extent of complexing by N.M.R. spectroscopy

Abstract

The tautomeric equilibrium of D-allose in aqueous solution is altered by the presence of some cations which form complexes with the a-pyranose and the a-furanose but not with the ß-pyranose and the ß-furanose forms. Determination of the proportions of the tautomeric forms by N.M.R. allows a comparison of the complexing ability of cations. Lanthanum, calcium, and strontium form the strongest complexes. The behaviour of D-lyxose, D-ribose, and D- glycero-D-gulo -heptose on complexing is described.