Draw the products of each of the following S_N2/E2 reactions. If the products can exist as stereoisomers, show which stereoisomers are formed.


c. (3S,4R)-3-bromo-4-methylhexane + CH₃O⁻

Verified step by step guidance

1. Identify the type of reaction: The problem involves SN2 and E2 reactions. Determine which mechanism is more likely based on the substrate and nucleophile/base.
2. Analyze the substrate: (3S,4R)-3-bromo-4-methylhexane is a secondary alkyl halide, which can undergo both SN2 and E2 reactions.
3. Consider the nucleophile/base: CH3O− is a strong nucleophile and a strong base, which can promote both SN2 and E2 reactions.
4. Predict the SN2 reaction product: In an SN2 reaction, the nucleophile attacks the carbon with the leaving group (bromine) from the opposite side, leading to inversion of configuration at the chiral center.
5. Predict the E2 reaction product: In an E2 reaction, the base abstracts a proton from a β-carbon, leading to the formation of a double bond. Consider the stereochemistry of the starting material to determine the possible stereoisomers of the alkene product.

Key Concepts

S_N2 Reaction Mechanism

The S_N2 (substitution nucleophilic bimolecular) reaction involves a nucleophile attacking an electrophile, resulting in the simultaneous displacement of a leaving group. This mechanism is characterized by a single concerted step, leading to inversion of configuration at the carbon center where substitution occurs. Understanding this mechanism is crucial for predicting the stereochemical outcomes of reactions involving chiral centers.

E2 Reaction Mechanism

The E2 (elimination bimolecular) reaction is a concerted process where a base abstracts a proton while a leaving group departs, resulting in the formation of a double bond. This mechanism typically requires a specific geometric arrangement of atoms, often leading to the formation of alkenes. Recognizing the conditions under which E2 occurs, such as the need for strong bases and the stereochemistry of the substrate, is essential for predicting the products.

Stereoisomerism

Stereoisomerism refers to the phenomenon where compounds have the same molecular formula and connectivity but differ in the spatial arrangement of atoms. In the context of organic reactions, especially those involving chiral centers, understanding how stereoisomers can form is vital. The products of S_N2 and E2 reactions can lead to different stereoisomers, and recognizing these configurations helps in accurately depicting the reaction outcomes.