Specific rotation of α and β -D-glucose.
A freshly prepared solution of α-D-glucose shows a specific rotation of +112∘. Over time, the rotation of this solution decreases and reaches an equilibrium value of +52.5∘. In contrast, a freshly prepared solution of β-D-glucose has a specific rotation of +19∘. The rotation of this solution increases over time to the same equilibrium value of +52.5∘.
(a) Why do specific rotations of the freshly prepared samples change over time, and why do they reach the same equilibrium value?
(b) Compute the percentage of each anomer at equilibrium.