Synthesis of diethylacetal: thermodynamic and kinetic studies

The synthesis of diethylacetal was studied in a batch reactor by reacting ethanol and acetaldehyde in the liquid phase, using the acid resin Amberlyst 18 as catalyst. The reaction equilibrium constant was determined experimentally in the temperature range 293-333 K at 1.0 MPa: K-eq = 0.018 exp[1230/T]. The standard molar reaction properties were obtained at 298 K: DeltaH(0) = -10,225.9 J mol(-1), DeltaG(0) = -269.3 J mol(-1) and DeltaS(0) = - 33.395 J mol(-1) K-1. The standard molar properties of formation of acetal in the liquid phase at 298 K were estimated: DeltaH(f)(0) = - 476.18 kJ mol(-1), DeltaG(f)(0) = -239.42 kJ mol(-1) and S-f(0) = 291.3 J mol(-1) K-1. Kinetic experiments were carried out in the temperature range 289-299 K at 0.6 MPa. A two-parameter model based on a Langmuir-Hinshelwood rate expression, using activity coefficients from the UNIFAC method: can describe the experimental kinetic results. The proposed kinetic law is r = k(C)[a(A)a(B) - a(C)a(D)/(K(eq)a(A))]/(1 + K-I2 a(C)/a(A))(2), and the parameters are k(C) = 1.16 x 10(8) exp[-5758.2/T(K)] mol g(-1) min(-1) and K-I2 = 5.66 x 10(3) exp[-2206.4/T(K)]. The activation energy of reaction is 47.874 kJ mol(-1). (C) 2001 Elsevier Science Ltd. All rights reserved.