Synthesis of diethylacetal: thermodynamic and kinetic studies

The synthesis of diethylacetal was studied in a batch reactor by reacting e thanol and acetaldehyde in the liquid phase, using the acid resin Amberlyst 18 as catalyst. The reaction equilibrium constant was determined experimen tally 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. Kine tic 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 exper imental 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) ex p[-2206.4/T(K)]. The activation energy of reaction is 47.874 kJ mol(-1). (C ) 2001 Elsevier Science Ltd. All rights reserved.