Draw the substitution and elimination products for the following reactions, showing the configuration of each product:
b. cis-1-chloro-2-methylcyclohexane + CH₃O⁻

Verified step by step guidance

1. Analyze the structure of the starting material, cis-1-chloro-2-methylcyclohexane. The chlorine atom is on one carbon of the cyclohexane ring, and the methyl group is on the adjacent carbon. Both substituents are on the same side of the ring (cis configuration).
2. Identify the reagent, CH3O− (methoxide ion), which is a strong base and a good nucleophile. This means that both substitution (SN2 or SN1) and elimination (E2 or E1) reactions are possible, depending on the reaction conditions.
3. For the substitution product: In an SN2 reaction, the methoxide ion will attack the carbon bonded to the chlorine atom (the leaving group) from the opposite side, leading to an inversion of configuration at that carbon. Draw the product with the methoxy group replacing the chlorine, ensuring the stereochemistry reflects the inversion.
4. For the elimination product: In an E2 reaction, the methoxide ion will abstract a β-hydrogen (a hydrogen on a carbon adjacent to the carbon bearing the chlorine). Since the starting material is in the cis configuration, consider the anti-periplanar geometry required for E2 elimination. Draw the resulting alkene, ensuring the correct stereochemistry of the double bond.
5. Verify the stereochemistry of all products. For the substitution product, confirm the inversion of configuration. For the elimination product, ensure the double bond is correctly placed and the stereochemistry of the alkene (E or Z) is consistent with the starting material's geometry.

Key Concepts

Substitution Reactions

Substitution reactions involve the replacement of one functional group in a molecule with another. In organic chemistry, this often occurs with alkyl halides, where a nucleophile attacks the carbon atom bonded to the leaving group (e.g., Cl) and replaces it. Understanding the mechanism (SN1 or SN2) is crucial, as it influences the stereochemistry and the nature of the products formed.

Elimination Reactions

Elimination reactions involve the removal of a small molecule (like HCl or H2O) from a larger molecule, resulting in the formation of a double bond. In the context of the given reaction, the base (CH3O−) abstracts a proton, leading to the formation of an alkene. The regioselectivity and stereochemistry of the elimination products depend on the structure of the starting material and the reaction conditions.

Stereochemistry

Stereochemistry refers to the spatial arrangement of atoms in molecules and how this affects their chemical behavior. In the context of the given reaction, the configuration of the products (cis or trans) is important, especially when dealing with cyclic compounds like cyclohexane. Understanding how stereochemistry influences reactivity and product formation is essential for predicting the outcomes of substitution and elimination reactions.