Indicate whether each pair of Fischer projections represents enantiomers or identical structures.
b.

Verified step by step guidance

1. Step 1: Recall the definition of enantiomers. Enantiomers are non-superimposable mirror images of each other, meaning they have the same connectivity but opposite configurations at all chiral centers.
2. Step 2: Examine the Fischer projections provided in the problem. Identify the chiral centers in each structure and note the arrangement of substituents around these centers.
3. Step 3: Compare the configurations of the chiral centers in the two Fischer projections. For each chiral center, determine whether the substituents are arranged in the same way (identical) or in opposite configurations (enantiomers).
4. Step 4: Check for superimposability. If the two Fischer projections can be rotated or flipped to perfectly overlap, they are identical. If they cannot be superimposed but are mirror images, they are enantiomers.
5. Step 5: Conclude whether the pair of Fischer projections represents enantiomers or identical structures based on your analysis of the chiral centers and superimposability.

Key Concepts

Fischer Projections

Fischer projections are a two-dimensional representation of three-dimensional organic molecules, particularly useful for depicting stereochemistry. In these diagrams, vertical lines represent bonds that project away from the viewer, while horizontal lines represent bonds that project towards the viewer. This format is commonly used to illustrate the configurations of chiral centers in carbohydrates and amino acids.

Enantiomers

Enantiomers are a type of stereoisomer that are non-superimposable mirror images of each other. They typically arise from molecules that contain one or more chiral centers, where the arrangement of substituents around the chiral center leads to two distinct configurations. Enantiomers have identical physical properties in most respects but can exhibit different biological activities and reactivities.

Identical Structures

Identical structures refer to molecules that have the same connectivity and spatial arrangement of atoms, meaning they are superimposable on one another. In the context of Fischer projections, if two representations can be rotated or flipped to match exactly, they are considered identical. Understanding the distinction between identical structures and enantiomers is crucial for analyzing stereochemical relationships in organic compounds.