Consider the following statements:

• Statement I: Glucose exists in two anomeric forms.
• Statement II: α-D-Glucose has a higher melting point than β-D-Glucose.
• Statement III: α-D-Glucose has optical rotation +19° and β-D-Glucose has +112°.
• Statement IV: α-D-Glucose and β-D-Glucose are anomers.

Choose the correct option.

Glucose is one of the most important monosaccharides and exists predominantly in cyclic hemiacetal forms. During ring formation, a new chiral carbon known as the anomeric carbon is produced. As a result, glucose exists in two anomeric forms:

• α-D-Glucose
• β-D-Glucose

Therefore, Statement I is correct.

Now examine Statement II.

The melting point of β-D-glucose is actually higher than that of α-D-glucose because β-D-glucose possesses a more stable arrangement of substituents. Hence Statement II is incorrect.

Consider Statement III.

The specific rotations are:

• α-D-Glucose = +112°
• β-D-Glucose = +19°

The values given in the statement are reversed. Therefore Statement III is incorrect.

Statement IV states that α-D-glucose and β-D-glucose are anomers. This is correct because they differ only in the configuration around the anomeric carbon atom.

Thus:

• Statement I = Correct
• Statement II = Incorrect
• Statement III = Incorrect
• Statement IV = Correct

Anomerism is a special type of stereoisomerism found in carbohydrates. The interconversion between α and β forms in aqueous solution is called mutarotation, which results in a gradual change in optical rotation until equilibrium is reached.

Correct Option: (1) I and IV only