Kinetics and Equilibrium Data of the Dehydration-Hydration Reaction between Diacetone Alcohol and Mesityl Oxide in Phosphoric Acid

Article abstract of DOI:10.1021/je00040a005

The velocities of dehydration of diacetone alcohol and hydration of mesityl oxide were studied in regions of 8.6-85.2percent phosphoric acid.Because the reactions are acid-catalyzed, the reaction velocities in both directions were increased as the acid concentration increased.The reaction kinetics fit the reversible first-order model with respect to the concentration of reactants, including the activity of water.These results are consisted with the mechanisms proposed by a previous investigator in which the rate-determining step is addition or removal of protons.Equilibrium constants were derived from solution composition and specific rate constants which agreed with each other.The equilibrium constant did not change with with acid concentration in the dilute range, but increased slightly at higher acid concentrations.The reaction velocities and the equilibrium constants increased with increasing temperature, and the activation energies were 18.8 and 12.7 kcal/mol for the dehydration and hydration reactions, respectively.