Kinetic correlation of Diels-Alder reactions in supercritical carbon dioxide

The Diels-Alder reaction of cyclopentadiene and ethyl acrylate was explored in supercritical CO2 from 38 to 88 degrees C and pressures from 80 to 210 bar. A traditional Arrhenius expression was used to correlate the kinetic data at a constant density of 0.5 g/cm(3). Over the temperature range investigated, the activation energy was found to be 40 +/- 2 kJ/mol. Traditional transition state theory was used to explore the temperature and density effects on the reaction rate. However, all that is required to accurately predict the global rate constant for this reaction is an empirically-determined activation energy and a pre-exponential term with a linear dependence on the density of solution. An examination of data from other researchers suggests that this is also true for other Diels-Alder reactions in supercritical CO2.