The formation of furanose structure of fructose involves the interaction of functional groups present at :

Options

A. C-1 and C-4
B. C-2 and C-6
C. C-2 and C-5
D. C-1 and C-5

Answer

To solve the question regarding the formation of the furanose structure of fructose, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of Fructose**:
- Fructose is a ketose sugar, meaning it contains a ketone functional group. In its open-chain form, it has a carbonyl group (C=O) at the second carbon (C2) and hydroxyl groups (-OH) attached to the other carbons.

2. **Draw the Open-Chain Structure**:
- The open-chain structure of fructose can be represented as:
```
CH2OH
|
C=O
|
CHOH
|
CH2OH
```
- Here, the carbonyl group is at C2.

3. **Identify the Functional Groups**:
- The key functional groups in fructose are the carbonyl group at C2 and the hydroxyl groups at C1, C3, C4, and C5.

4. **Formation of the Furanose Ring**:
- The furanose structure is a five-membered ring. To form this ring, the hydroxyl group on C5 will attack the carbonyl carbon (C2).
- This reaction involves the nucleophilic attack of the hydroxyl oxygen on the electrophilic carbonyl carbon.

5. **Count the Carbons in the Ring**:
- When the ring is formed, it will consist of four carbons from the open-chain structure and one oxygen atom. The carbons involved in the furanose ring will be:
- C2 (carbonyl carbon)
- C3
- C4
- C5 (the carbon with the hydroxyl group that attacks)

6. **Conclusion**:
- The interaction of functional groups that leads to the formation of the furanose structure involves the carbonyl group at C2 and the hydroxyl group at C5. Therefore, the correct answer is that the functional groups involved are present at carbon 2 and carbon 5.

### Final Answer:
The formation of the furanose structure of fructose involves the interaction of functional groups present at carbon 2 and carbon 5.