Which carbon is anomeric carbon in cyclic structure of glucose?

Options

A. `C_(1)`
B. `C_(2)`
C. `C_(3)`
D. `C_(4)`

Explanation

To determine which carbon is the anomeric carbon in the cyclic structure of glucose, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Structure of Glucose**:
Glucose is an aldohexose, meaning it has six carbon atoms and contains an aldehyde group in its open-chain form.

2. **Understand the Cyclic Form**:
When glucose cyclizes, it typically forms a pyranose ring, which consists of six atoms (five carbons and one oxygen).

3. **Locate the Carbonyl Group**:
In the open-chain form of glucose, the carbonyl group (C=O) is located at the first carbon (C1).

4. **Formation of the Anomeric Carbon**:
When the cyclic structure forms, the oxygen atom from the fifth carbon (C5) attacks the carbonyl carbon (C1). This reaction leads to the formation of a new bond and the creation of a new hydroxyl group on the anomeric carbon.

5. **Identify the Anomeric Carbon**:
The anomeric carbon is defined as the carbon that was the carbonyl carbon in the open-chain form. In the case of glucose, this is the first carbon (C1) of the cyclic structure.

6. **Distinguish Between Alpha and Beta Forms**:
The configuration of the hydroxyl group on the anomeric carbon (C1) determines whether the cyclic glucose is in the alpha (α) or beta (β) form. If the hydroxyl group is below the plane of the ring, it is beta-D-glucose; if it is above, it is alpha-D-glucose.

### Conclusion:
The anomeric carbon in the cyclic structure of glucose is **C1**.

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