Question

What is the difference between an enantiomer and a diastereomer?

Short answer

Enantiomers are non-superimposable mirror images; diastereomers are not mirror images and have different physical properties.

Step-by-step solution

- Define Enantiomers

Enantiomers are stereoisomers that are non-superimposable mirror images of each other. They have the same molecular formula and sequence of bonded atoms (constitution), but they differ in the three-dimensional orientations of their atoms in space.

- Define Diastereomers

Diastereomers are stereoisomers that are not mirror images of each other. Unlike enantiomers, diastereomers have different physical properties and are not non-superimposable mirror images.

- Contrast Enantiomers and Diastereomers

The key difference between enantiomers and diastereomers is that enantiomers are mirror images that cannot be superimposed, while diastereomers are not mirror images and have different physical properties.

Key concepts

Stereoisomers

Stereoisomers are a type of isomer where molecules have the same molecular formula and sequence of bonded atoms (also known as their constitution) but differ in the three-dimensional orientations of their atoms in space. Start by imagining Lego blocks: you have the same blocks, building structures identical in their format. However, when these structures are manipulated in space, they can show different spatial arrangements. This unique property differentiates stereoisomers from other types of isomers like structural isomers.

Molecular Formula

The molecular formula of a compound gives a simple count of the number of different types of atoms that are present. For example, the molecular formula for glucose is C₆H₁₂O₆, which means each glucose molecule consists of six carbon atoms, twelve hydrogen atoms, and six oxygen atoms. While molecular formulas provide information on the types and numbers of atoms, they do not say anything about the arrangements of these atoms. This is where the concept of stereochemistry becomes important because stereoisomers share the same molecular formula but differ in their spatial arrangements.

Three-Dimensional Orientations

Three-dimensional orientation refers to the unique way atoms are arranged in space. Enantiomers, for example, are stereoisomers that are non-superimposable mirror images. Imagine your left and right hands; they are mirror images but can't perfectly align no matter how you position them. This three-dimensional aspect leads to differing physical and chemical properties. Diastereomers, on the other hand, are also stereoisomers but are not mirror images and are non-superimposable. Think of them as siblings who look similar but have distinct physical features. Both enantiomers and diastereomers exemplify the fascinating world of three-dimensional molecular arrangements.