A carbon atom which is bonded to four different groups in an assymetric carbon atom.Glucose with six carbon atom has four assymetric carbon atom.

Asymmetric Carbon Atoms in α-D-Glucose

α-D-glucose is a monosaccharide and a common sugar found in nature. It is a hexose sugar, meaning it has six carbon atoms. To determine the number of asymmetric carbon atoms present in α-D-glucose, we need to understand the concept of chirality and how it relates to carbon atoms.

Chirality and Asymmetric Carbon Atoms

Chirality refers to the property of an object that is not superimposable on its mirror image. In the context of organic chemistry, chiral molecules have a central carbon atom (known as an asymmetric carbon or chiral center) attached to four different substituents. The presence of an asymmetric carbon atom in a molecule leads to the existence of stereoisomers, which are non-superimposable mirror images of each other.

Structure of α-D-Glucose

α-D-glucose has a molecular formula of C6H12O6. It is a cyclic sugar, existing predominantly in the cyclic hemiacetal form. The cyclic structure of glucose consists of a six-membered ring with five carbon atoms and one oxygen atom, known as a pyranose ring.

Number of Asymmetric Carbon Atoms

In α-D-glucose, there are four asymmetric carbon atoms, indicated by the asterisks (*) in the structure below:

H OH
| |
HOCH2----C*----C----OH
| |
H OH

Explanation

1. The carbon atoms numbered 2, 3, 4, and 5 in the structure of α-D-glucose are asymmetric carbon atoms.
2. Each of these carbon atoms is bonded to four different substituents: one hydrogen atom (H) and three hydroxyl groups (OH).
3. The presence of these asymmetric carbon atoms gives rise to different stereoisomers of α-D-glucose.
4. The stereoisomers include enantiomers, which are mirror images of each other, and diastereomers, which are not mirror images.
5. The number of possible stereoisomers for a compound with 'n' asymmetric carbon atoms is 2^n. Therefore, α-D-glucose can exist as 2^4 = 16 stereoisomers.

Conclusion

In α-D-glucose, there are four asymmetric carbon atoms. These carbon atoms are crucial for the formation of different stereoisomers, contributing to the diverse properties and functions of glucose in biological systems. Understanding the presence and arrangement of asymmetric carbon atoms is essential in the study of carbohydrates and their role in various biological processes.