Kinetics and mechanism of Pechmann condensation reaction over sulphated zirconia-supported zinc oxide

摘要: Abstract An investigation of the kinetics Pechmann condensation reaction over ZnO supported on sulphated zirconia (ZnO/SZ) catalyst has been performed. The ZnO/SZ contains both Lewis (L) and Bronsted (B) acid sites. maximum B/L ratio was obtained with a content 6%. is first-order half in acetoacetate resorcinol, which supports proposed mechanism. temperature found to have great effect coumarin synthesis, activation energy determined be 42.29 kJ mol−1. experimental parameters for were calculated ΔH≠ = 39.20 kJ mol−1, ΔS≠ = −152.62 J mol−1 K−1 ΔG≠ = 99.18 kJ mol−1 at 393 K. negative value entropy (ΔS≠) indicates that decreases upon forming transition state, proves state more highly ordered than reactants.