Which of the following is NOT a reason why the given elimination reaction is favorable?

• A. ΔH is negative.
• B. The nucleophile is a strong, anion nucleophile.
• C. The product base is weaker than the reagent base.
• D. ΔS is positive.

Answer: (B)

Verified step by step guidance

1. Identify the type of reaction: The reaction shown is an elimination reaction, specifically an E2 reaction, where a base removes a proton adjacent to a leaving group, resulting in the formation of a double bond.
2. Analyze the enthalpy change (ΔH): A negative ΔH indicates that the reaction is exothermic, meaning it releases energy, which is generally favorable for a reaction.
3. Consider the entropy change (ΔS): A positive ΔS suggests an increase in disorder, which is favorable for the reaction as it leads to a more disordered system, such as the formation of multiple products from a single reactant.
4. Evaluate the strength of the bases: The product base (ethanol) is weaker than the reagent base (ethoxide ion), which is favorable as it suggests the reaction proceeds towards the formation of a more stable, weaker base.
5. Assess the role of the nucleophile: The statement 'The nucleophile is a strong, anion nucleophile' is not a reason for the favorability of the elimination reaction, as the strength of the nucleophile is more relevant to substitution reactions rather than elimination reactions.