JEE Main levelSingle correct optionDifficulty 2 of 3g3186
Match the reaction in Column I with the type of control in Column II.
Column I: (P) HBr + buta-1,3-diene at −80∘C; (Q) naphthalene + conc. HX2SOX4 at 160∘C for a long time giving the 2-sulfonic acid; (R) ketone + LDA in THF at −78∘C; (S) enolate formation from a ketone under equilibrating conditions (NaOEt/EtOH, 25∘C).
Column II: (1) kinetic control; (2) thermodynamic control.
AP-1, Q-1, R-1, S-2
BP-2, Q-1, R-2, S-1
CP-1, Q-2, R-1, S-2
DP-1, Q-2, R-2, S-1
Answer: C
Low temperature with irreversible steps (P, R) gives the faster-forming kinetic product. Long reaction time at high temperature and reversible proton transfer (Q, S) give the more stable thermodynamic product.