Are the following pairs identical, enantiomers, diastereomers, or constitutional isomers?
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Verified step by step guidance

1. Identify the type of isomerism involved: Determine if the molecules are stereoisomers (same connectivity, different spatial arrangement) or constitutional isomers (different connectivity).
2. Check for chirality: Determine if the molecules have chiral centers by identifying carbon atoms bonded to four different groups.
3. Assign R/S configuration: For each chiral center, assign the R or S configuration using the Cahn-Ingold-Prelog priority rules.
4. Compare configurations: Compare the R/S configurations of the chiral centers in both molecules to determine if they are identical, enantiomers, or diastereomers.
5. Evaluate connectivity: If the connectivity of atoms is different, then the molecules are constitutional isomers.

Key Concepts

Stereoisomers

Stereoisomers are compounds that have the same molecular formula and connectivity of atoms but differ in the spatial arrangement of their atoms. This category includes enantiomers and diastereomers, which are crucial for understanding the relationships between different isomers. Enantiomers are non-superimposable mirror images, while diastereomers are not mirror images and have different physical properties.

Enantiomers

Enantiomers are a specific type of stereoisomer that are mirror images of each other and cannot be superimposed. They typically arise in molecules with chiral centers, where the arrangement of substituents around the chiral carbon creates two distinct forms. Enantiomers often exhibit different optical activities, meaning they rotate plane-polarized light in opposite directions.

Diastereomers

Diastereomers are stereoisomers that are not mirror images of each other and have different physical and chemical properties. They occur when a molecule has two or more chiral centers, leading to multiple stereoisomeric forms. Unlike enantiomers, diastereomers can have different boiling points, melting points, and reactivity, making their identification important in organic chemistry.