Kinetic Study on Phthalates

To assess the thermal stability of phthalates a flow reactor with a jet nozzle was developed by the authors. Thermal decomposition reactions of phthalates, each having a high boiling point and viscosity, were conducted with this reactor for a short period from 2.4∼8.4 s. The phthalate were found from the results to decompose by cis elimination into the usual esters at 250∼500°C. Assuming first order reactions, activation energy determined when using a fixed quantity of unreacted phthalate was found to be as follows; dibutyl phthalate, 22.4; dihexyl phthalate, 38.4; dioctyl phthalate, 45.0; di(2-ethylhexyl) phthalate, 40.6; didecyl phthalate, 35.4; and dilaulyl phthalate, 24.2 kcal/mol.