Question

What is essentially the difference between $$\alpha$$ - glucose and $$\beta$$- glucose? What is meant by pyranose structure of glucose?

Answer 1

Hint:$$\alpha$$ - glucose and $$\beta$$- glucose are two anomers. Furanose form contains 5 member rings whereas the pyranose form contains 6 member rings.

Complete answer:
Write the open chain structure of glucose:

Glucose has two cyclic hemiacetal forms. These two cyclic hemiacetal forms of glucose are called $$\alpha$$ - glucose and $$\beta$$- glucose. These two forms have different configurations of the hydroxyl group of the anomeric carbon atom. All the other things are the same for the two forms. Thus, $$\alpha$$ - glucose and $$\beta$$- glucose are two anomers.
You can classify $$\alpha$$ - glucose and $$\beta$$- glucose as stereoisomers as they have different three-dimensional arrangements of atoms/groups.
In the structure of $$\alpha$$ - glucose, the hydroxyl group present on the first carbon atom is down whereas in the structure of $$\beta$$ - glucose, the hydroxyl group present on the first carbon atom is up.
The furanose structure represents the five-membered cyclic structure of glucose.
In the furanose structure of glucose, the oxygen atom is present in the five membered ring
Due to this, the furanose form resembles furan, hence it is named as furanose form.

The pyranose structure represents the six-membered cyclic structure of glucose.
In the pyranose structure of glucose, the oxygen atom is present in the six membered ring
Due to this, the pyranose form resembles pyran, hence it is named as pyranose form.

Note:
Glucose is a simple carbohydrate. It is a monosaccharide with the formula $${\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_6$$ . It is a reducing sugar as it has a free aldehyde group. Glucose is an example of aldohexose as it contains six carbon atoms out of which one carbon atom is in the form of an aldehyde group.