Glycosidation of sugars. IV. Methanolysis of D-glucose, D-galactose, and D-mannose

Abstract

Rates of methanolysis reactions of D-glucose, D-galactose, and D-mannose have been determined. The results confirm those found earlier for pentoses that the glycosidation reaction proceeds to equilibrium through four distinguishable competing reactions: (1) hexose → furanosides, (2) anomerization of furanosides, (3) furanosides → pyranosides, and (4) anomerization of pyranosides. The glycoside compositions at equilibrium are interpreted in terms of conformational analysis for furanoid and pyranoid rings. The energy differences between the ground states also contribute to an important degree in determining the relative rates of reaction.