Ring Structure of. Glucose

1. CHEMISTRY DEPARTMENT, MAHARANA PRATAP P. G. COLLEGE, JUNGLE DHUSAN, GORAKHPUR
DR. S. K. VERNWAL
Head, Chemistry Department
Maharana Pratap P. G. College
Jungle Dhusan, Gorakhpur

2. CHEMISTRY DEPARTMENT, MAHARANA PRATAP P. G. COLLEGE, JUNGLE DHUSAN, GORAKHPUR
Ring Structure of
Glucose

3. CHEMISTRY DEPARTMENT, MAHARANA PRATAP P. G. COLLEGE, JUNGLE DHUSAN, GORAKHPUR
Limitations of Open Chain Structure of Glucose
Although the open chain structure of D(+)-Glucose
explains most of its reactions but it fails to explain the
following facts-
1. D(+)-Glucose does not undergo certain characteristic
reactions of aldehydic group. Eg. It does not form addition
product with Sodium bisulphite and does not respond to
Schiff’s reagent test.
2. The UV spectrum of glucose does not show the presence
of aldehydic group.
3. D(+)-Glucose exists in two stereoisomeric forms ie.
α-D(+)-Glucose and β-D(+)-Glucose which differ in their
physical properties.
4. Both α-D(+)-Gglucose and β-D(+)-Glucose undergo
mutarotation in aqueous solution.

4. CHEMISTRY DEPARTMENT, MAHARANA PRATAP P. G. COLLEGE, JUNGLE DHUSAN, GORAKHPUR
All the properties of glucose can not be
explained on the basis of its open chain structure.
Ring Structure of Glucose
In order to explain these properties, Tollen
proposed the ring structure of glucose.

5. CHEMISTRY DEPARTMENT, MAHARANA PRATAP P. G. COLLEGE, JUNGLE DHUSAN, GORAKHPUR
He suggested that glucose does not contain a
free aldehydic group, but it has a six membered
cyclic hemi acetal structure due to interaction
between –CHO group at C-1 and –OH group at C-5
position.
As a result C-1 becomes asymmetric and two
stereoisomers are formed which differ in
configuration only around C-1. These
stereoisomers are called as α-D(+)- glucose and β-
D(+)- glucose which are anomers to each other as
shown below.

6. CHEMISTRY DEPARTMENT, MAHARANA PRATAP P. G. COLLEGE, JUNGLE DHUSAN, GORAKHPUR
The structure of α-D(+)-Glucose and β-D(+)-
Glucose can be drawn in a simple six membered ring
form called pyranose structure. These structures were
suggested by Haworth and are known as Haworth
projection formula as shown below-

7. CHEMISTRY DEPARTMENT, MAHARANA PRATAP P. G. COLLEGE, JUNGLE DHUSAN, GORAKHPUR

8. CHEMISTRY DEPARTMENT, MAHARANA PRATAP P. G. COLLEGE, JUNGLE DHUSAN, GORAKHPUR

9. CHEMISTRY DEPARTMENT, MAHARANA PRATAP P. G. COLLEGE, JUNGLE DHUSAN, GORAKHPUR

10. CHEMISTRY DEPARTMENT, MAHARANA PRATAP P. G. COLLEGE, JUNGLE DHUSAN, GORAKHPUR