Illustrated Glossary of Organic Chemistry

Anomeric effect: Originally defined as the tendency of heteroatomic substituents (such as an OH group) adjacent to a heteroatom within a cyclohexane ring to prefer the axial orientation instead of the less hindered equatorial orientation that would be expected from steric considerations alone. Now defined more broadly as the tendency of a molecular fragment X-C-C-Y (where X and Y are heteroatoms) to prefer a gauche conformation.

Equatorial cyclohexanol		Axial cyclohexanol

In cyclohexanol, the ratio of conformations is about 80:20 equatorial:axial.

β-D-glucopyranose		α-D-glucopyranose