Research on the Kinetics of Thermal Isomerization Reaction of Mesoisomer of Diethyl 2,3-Dicyano-2,3-diphenylsuccinate in Aromatic Compound Solvents by HPLC

Abstract

The kinetics behaviour, activation parameters of thermal isomerization of meoisomer of diethyl 2,3-dicyano-2,3-diphenylsuccinate (1) in the aromatic compound solvents are investigated by external standard methods with HPLC at different temperatures of 90°C, 100°C, 110°C and 120°C, under protection of nitrogen gas. The relative error and the standard deviation of the quantitative analysis are less than ± 0.65% and 0.35, respectively. The experimental results show that both equilibrium constant K and standard free energy ΔG⁰ of thermal isomerization reaction of compound 1 in different solvents are insensitive to the reaction temperature and the kinds of solvents.

The observed activation energy E_a is nearly equal to the activation enthalpy ΔH. However, the value of activation entropy ΔS is different and negative. In addition, the observed rate constant k_obs is also insensitive to the kinds of solvents, but is greatly affected by the temperature.