Question

How many chiral centers are present in D-glucose? in D-ribose?

Short answer

Answer: There are four chiral centers in D-glucose and three chiral centers in D-ribose.

Step-by-step solution

Understanding Chiral Centers

A chiral center (or stereocenter) is an atom within a molecule that has four different groups attached to it. The most common type of chiral center is a carbon atom bonded to four different groups. When a chiral center is present in a molecule, it can exist in two different configurations called enantiomers, which are mirror images of each other and cannot superimpose onto one another.

Identifying Chiral Centers in D-Glucose

D-glucose is an aldohexose sugar, which means it has six carbons and one of them is an aldehyde group. The structure of D-glucose is: H | HO-C | HO-C - H | HO-C - H | HO-C - H | CH2OH To determine the chiral centers in D-glucose, we should find the carbon atoms that have four different groups attached to them. D-glucose contains four such carbon atoms (C2, C3, C4, and C5), where each carbon is bonded to one hydroxyl group (OH), one hydrogen atom (H), and two other different carbon atoms. Therefore, there are four chiral centers in D-glucose.

Identifying Chiral Centers in D-Ribose

D-ribose is an aldopentose sugar, which means it has five carbons and one of them is an aldehyde group. The structure of D-ribose is: H | HO-C | HO-C - H | HO-C - H | CH2OH To determine the chiral centers in D-ribose, we should find the carbon atoms that have four different groups attached to them. D-ribose contains three such carbon atoms (C2, C3, and C4), where each carbon is bonded to one hydroxyl group (OH), one hydrogen atom (H), and two other different carbon atoms. Therefore, there are three chiral centers in D-ribose.