Thermal stability of phthalic esters

Phthalic esters, as typical plasticizers for vinyl plastics, were thermally decomposed by a flow reactor system and their decomposition products were analyzed in detail. The thermal decomposition products were olefin, alcohol, hydrogen phthalate, benzoates with alkyl groups corresponding to these of the original phthalate esters and phthalic anhydride. We found from the main thermal decomposotion products-olefin, alcohol and hydrogen phthalate-that phthalic esters were thermally decomposed throughcis-elimination in the same way as in the general case for esters. In the presence of polyvinyl chloride (PVC), hydrochlorinated products were identified in the decomposition products. A good relationship was found between the amount of chloroalkanes produced and the reaction temperature. Thecis-elimination reaction of phthalic esters was found to be promoted by PVC.