Site pages
Current course
Participants
General
Topic 1
Topic 2
Topic 3
Topic 4
Topic 5
Topic 6
Topic 7
Topic 8
Topic 9
Topic 10
Topic 11
Topic 12
Topic 13
Topic 14
Topic 15
Topic 16
Topic 17
Topic 18
Topic 19
Topic 20
Topic 21
Topic 22
Topic 23
Topic 24
Topic 25
Topic 26
Topic 27
3.2.3.3 Mutarotation
The optical rotation of a freshly prepared solution of glucose gradually decreases and finally becomes constant. This change in the rotation of sugar solutions upon standing is called “mutarotation”. It is a general property of reducing sugars.
When D-glucose is crystallized from water or dilute alcohol at room temperature, a form separates having an initial specific optical rotation of +112o which changes to +52.5o. If, it is crystallized from water at temperatures above 98oC, a different form of glucose, having an initial specific rotation of +19o which changes to +52.5o, is obtained. The first of these isomers of glucose was called “α-D-glucose” and the second “β-D-glucose”. Glucose exists in different isomeric forms in solution which change into the same equilibrium mixture regardless of which form is dissolved.
|