(c) How many asymmetric carbons and stereoisomers are there for an aldohexose? For a ketohexose?

Verified step by step guidance

1. Identify the structure of an aldohexose: An aldohexose is a monosaccharide with six carbon atoms and an aldehyde group at the first carbon.
2. Determine the number of asymmetric carbons in an aldohexose: In an aldohexose, the second to fifth carbon atoms are chiral centers, resulting in 4 asymmetric carbons.
3. Calculate the number of stereoisomers for an aldohexose: Use the formula 2^n, where n is the number of asymmetric carbons. For an aldohexose, n = 4, so the number of stereoisomers is 2^4.
4. Identify the structure of a ketohexose: A ketohexose is a monosaccharide with six carbon atoms and a ketone group at the second carbon.
5. Determine the number of asymmetric carbons in a ketohexose: In a ketohexose, the third to fifth carbon atoms are chiral centers, resulting in 3 asymmetric carbons. Calculate the number of stereoisomers for a ketohexose using the formula 2^n, where n is the number of asymmetric carbons. For a ketohexose, n = 3, so the number of stereoisomers is 2^3.

Key Concepts

Asymmetric Carbons

Asymmetric carbons, or chiral centers, are carbon atoms that are bonded to four different substituents, leading to non-superimposable mirror images known as enantiomers. In carbohydrates, the presence of asymmetric carbons is crucial for determining the molecule's stereochemistry, which affects its biological function and properties.

Stereoisomers

Stereoisomers are compounds that have the same molecular formula and connectivity of atoms but differ in the spatial arrangement of their atoms. For carbohydrates, the number of stereoisomers can be calculated using the formula 2^n, where n is the number of asymmetric carbons, highlighting the complexity and diversity of sugar structures.

Aldohexose vs. Ketohexose

Aldohexoses and ketohexoses are types of hexose sugars distinguished by their functional groups. Aldohexoses contain an aldehyde group at one end, while ketohexoses have a ketone group typically at the second carbon. This difference in functional groups influences the number of asymmetric carbons and, consequently, the total number of stereoisomers for each type of sugar.