Facile and catalytic degradation method of DDT using Pd/C–Et 3N system under ambient pressure and temperature

Abstract

The catalytic degradation method of p, p′-DDT [1,1,1-trichloro-2,2-bis( p-chlorophenyl)ethane] and its regioisomer o, p′-DDT [1,1,1-trichloro-2-( o-chlorophenyl)-2-( p-chlorophenyl)ethane] using the Pd/C–Et 3N system under ambient hydrogen pressure and temperature was established. The presence of Et 3N was necessary for the quick and complete breakdown of DDT. The independent degradation study of two intermediates, p, p′-DDD [2,2-bis( p-chlorophenyl)-1,1-dichloroethane] and p, p′-DDE [2,2-bis( p-chlorophenyl)-1,1-dichloroethylene] using GC–MS let us to speculate the degradation pathway of p, p′-DDT. In the initial phase of the reaction, p, p′-DDT degradation splits into two ways: a dehydrochlorination pathway and a hydrodechlorination pathway. In each pathway, reaction starts from an aliphatic moiety and subsequent hydrodechlorination from the benzene moieties takes place in a stepwise manner. The former pathway leads to the formation of 1,1-diphenylethane and the latter leads to the formation of 1,1-dichloro-2,2-diphenylethane. These diphenylethane analogs, which are less toxic compared with p, p′-DDT, are terminal degradation products in our system. The distinctive features of our catalytic degradation method of DDTs are reliability, simplicity, efficiency, and inexpensiveness.