Equilibrium Constants for the Liquid-Phase Synthesis of Isopropyl tert-Butyl Ether from 2-Propanol and Isobutene

Equilibrium constants for the liquid-phase addition of 2-propanol to isobutene to give isopropyl tert -butyl ether (IPTBE) were determined experimentally in the temperature range 303−353 K and at 1.6 MPa. To reach etherification equilibrium, the macroporous sulfonic resin Bayer K-2631 was used as the catalyst. The UNIFAC estimates of activity coefficients were used to describe the liquid-phase nonideality. The thermodynamic equilibrium constants and the enthalpy, free energy, and entropy changes of the reaction were given as a function of temperature. At 298.15 K, the standard molar reaction enthalpy Δ r H ° m (298.15 K) is −(22.9 ± 1.3) kJ·mol - 1, in agreement with literature data, and the standard molar reaction entropy Δ r S ° m (298.15 K) and free energy Δ r G ° m (298.15 K) are −(60.3 ± 0.5) J·(mol·K) - 1 and −(4.9 ± 1.4) kJ·mol - 1, respectively. Finally, at 298.15 K the standard molar enthalpy of formation Δ f H ° m (l, 298.15 K) and the standard molar entropy of IPTBE S ° m (l, 298.15 K) were estimated to be −(378.5 ± 2.7) kJ·mol - 1 and 337.6 ± 1.5 J·(mol·K) - 1, respectively.