When a monosaccharide forms a rings by interaction of one of its hydroxyl group with its aldehyde group, the bond is referred to as a (an) ……………….. Linkage

Options

A. Ether
B. Ester
C. Acetal
D. Hemiacetal

Answer

To answer the question regarding the type of linkage formed when a monosaccharide forms a ring by interaction of one of its hydroxyl groups with its aldehyde group, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Monosaccharides**:
- Monosaccharides are simple sugars that can exist in an open-chain form or a cyclic form. They contain functional groups such as aldehydes or ketones and hydroxyl groups.

2. **Identifying the Functional Groups**:
- In the case of an aldehyde monosaccharide, such as glucose, the molecule has a carbonyl group (C=O) at one end (the aldehyde group) and multiple hydroxyl (–OH) groups.

3. **Formation of the Ring Structure**:
- When a monosaccharide cyclizes, one of its hydroxyl groups reacts with the aldehyde group. This reaction involves the nucleophilic attack of the oxygen atom in the hydroxyl group on the electrophilic carbon atom of the aldehyde group.

4. **Formation of Hemiacetal**:
- The result of this reaction is the formation of a hemiacetal. A hemiacetal is formed when a carbon atom is bonded to an –OH group, an alkoxy group (–OR), and two other groups (which can be hydrogen or carbon chains).

5. **Identifying the Linkage**:
- The new bond formed between the carbon atom (originally part of the aldehyde) and the oxygen atom from the hydroxyl group is specifically called a hemiacetal linkage. This is because it involves the conversion of an aldehyde to a hemiacetal.

6. **Conclusion**:
- Therefore, the bond formed when a monosaccharide forms a ring by interaction of one of its hydroxyl groups with its aldehyde group is referred to as a **hemiacetal linkage**.

### Final Answer:
The bond is referred to as a **hemiacetal linkage**.