Research on the kinetics of thermal isomerization reaction of mesoisomer of diethyl 2,3-dicyano-2,3-diphenylsuccinate in aromatic compound solvents by HPLC

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 degrees C,100 degrees C,110 degrees C and 120 degrees 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 Delta G(0) 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 Delta H. However, the value of activation entropy Delta S 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.