For each structure,
1. star (*) any asymmetric carbon atoms.
2. label each asymmetric carbon as (R) or (S).
3. draw any internal mirror planes of symmetry.
4. label the structure as chiral or achiral.
5. label any meso structures.
(e)

Verified step by step guidance

1. Step 1: Identify all carbon atoms in the structure and determine if they are asymmetric. An asymmetric carbon is bonded to four different groups. In this structure, the two central carbon atoms are candidates for asymmetry.
2. Step 2: Assign priorities to the substituents around each asymmetric carbon based on the Cahn-Ingold-Prelog priority rules. Higher atomic numbers receive higher priority. For example, Br > CH2Br > H.
3. Step 3: Determine the configuration (R or S) of each asymmetric carbon using the priority rules and the 'right-hand rule' for stereochemistry. Orient the lowest priority group away from you and trace the path of the remaining groups in order of priority.
4. Step 4: Check for internal mirror planes of symmetry in the molecule. If a plane of symmetry exists, the molecule is achiral. In this case, the molecule has a vertical plane of symmetry passing through the center.
5. Step 5: Label the molecule as chiral or achiral. Since the molecule has a plane of symmetry and the two asymmetric carbons are mirror images of each other, it is a meso compound and achiral.

Key Concepts

Asymmetric Carbon Atoms

Asymmetric carbon atoms, also known as chiral centers, are carbon atoms that are bonded to four different substituents. This unique arrangement allows for the existence of two non-superimposable mirror images, known as enantiomers. Identifying these atoms is crucial for determining the chirality of a molecule, which affects its optical activity and interactions in biological systems.

Cahn-Ingold-Prelog Priority Rules

The Cahn-Ingold-Prelog (CIP) priority rules are a set of guidelines used to assign the (R) or (S) configuration to chiral centers. According to these rules, substituents attached to the asymmetric carbon are ranked based on atomic number, with higher atomic numbers receiving higher priority. The configuration is determined by the orientation of the substituents when the lowest priority group is oriented away from the viewer.

Chirality and Meso Compounds

Chirality refers to the property of a molecule that is not superimposable on its mirror image, indicating that it has a distinct left and right form. Meso compounds, however, are a special case of chirality where a molecule contains multiple chiral centers but is overall achiral due to an internal plane of symmetry. Recognizing meso structures is important for understanding the stereochemistry of complex molecules.