Intense applied heating drastically and irreversibly alters the mechanistic pathways of haloalkanes. — Haloalkanes and Haloarenes Chemistry Question
Question
Intense applied heating drastically and irreversibly alters the mechanistic pathways of haloalkanes. When evaluating the fierce kinetic competition exactly between $S_N2$ and $E2$ for a specific secondary alkyl halide reacting with alcoholic $KOH$, which of the following physical truths rigorously dictate exactly why extremely high heat strongly promotes the alkene elimination product over substitution?
💡 Solution & Explanation
A) True. In a concerted $E2$ elimination, multiple strong bonds must be aggressively reorganized simultaneously (violently breaking $C-H$ and $C-X$, while meticulously making a $C=C$ pi bond), generally resulting in a measurably higher activation energy ($E_{a(elim)}$) than simply displacing a leaving group in $S_N2$ ($E_{a(sub)}$). C) True. Based entirely on the fundamental Arrhenius exponential relationship ($k = Ae^{-E_a/RT}$), a higher applied temperature disproportionately and overwhelmingly accelerates the chemical reaction structurally possessing the larger activation energy. Thus, applying intense extreme heat violently boosts the rate of the typically sluggish $E2$ pathway much more significantly than the $S_N2$ pathway, rapidly causing elimination to eventually completely overtake substitution. (Option B is chemically false. Option D is completely false; intense heating absolutely does not magically change the fundamental molecularity or the concerted nature of the mechanism if a strong base is already actively present).