Thermodynamics of Aldol Condensation of Acetaldehyde

The standard enthalpies of formation,the standard Gibbs free energy of formation and the heat capacity of each compound in acetaldehyde condensation reaction system were calculated with the application of Yoneda group contribution method.Comparison of the calculated results with some literature values show that the calculation results are reliable.Then the reaction enthalpies,reaction Gibbs free energy changes and equilibrium constants of relevant reactions in this system from 278 K to 368 K in liquid phase and 600 K in vapor phase were calculated and analyzed.The results show that the temperature has important influence on the main reaction.Conducting the reactions in liquid phase at low temperature benefited the main reaction,while high temperature led to low conversion and selectivity.2,4-hexadienoic aldehyde was the main by-product.The thermodynamic analysis agreed well with experimental results.Acetaldehyde condensation is not recommended to proceed at high temperature.To improve the conversion and selectivity of practical reaction,the temperature is proposed be controlled reasonably or the main product needs to be separated from the reactant in time.