Under standard bimolecular elimination (E2) conditions, utilizing certain exceptionally bulky bases — Haloalkanes and Haloarenes Chemistry Question

💡 Solution & Explanation

The final regioselectivity of E2 eliminations is fundamentally dictated by the physical steric bulk of the attacking base. Small, unhindered bases like ethoxide, methoxide, and plain amide efficiently tunnel in to access internal, heavily shielded $\beta$ -hydrogens to form the thermodynamically stable Saytzeff product. However, sterically massive, heavily branched bases like potassium *tert*-butoxide and lithium diisopropylamide (LDA) violently physically collide with the surrounding alkyl chain. To minimize this severe steric repulsion, they are forcefully restricted to attacking only the most exposed, terminal, primary $\beta$ -hydrogens, resulting in the overwhelming, almost exclusive formation of the less substituted Hofmann alkene.