• The a- and b- anomers of carbohydrates are typically stable solids.
• However, in aqueous solution, they quickly equilibrate to an equilibrium mixture of the two forms.
• For example, in aqueous solution, glucose exists as a mixture of 36% a- and 64% b- (>99% of the pyranose forms exist in solution).
• The equilibration occurs via the ring opening of the cyclic sugar at the anomeric center with the acyclic form as the intermediate

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"Organic Chemistry" 5th ed.  by Francis A. Carey