HYDRODECHLORINATION OF 1,1-BIS(PARA-CHLOROPHENYL)-2,2-DICHLOROETHYLENE IN LIQUID-PHASE

The liquid-phase catalytic hydrodechlorination of 1,1-bis(p-chlorophenyl)-2,2-dichloroethylene (p,p′-DDE) was studied using 10% Pd on activated carbon and 61% Ni on kieselguhr catalysts. Reactions were carried out at temperatures of 20-100 °C and hydrogen pressures from 1 to 50 atm. Ethanol was used as a solvent, and NaOH was used as an acid acceptor for the HCl by-product of the hydrodechlorination reactions. Both catalysts resulted in a complex network of reactions characterized by three paths: the removal of both olefinic chlorines followed by hydrogenation of the olefin, consecutive aromatic hydrodechlorination, and simultaneous occurrence of both of these paths. The steps involve as many as five molecules of hydrogen reacting without the observable desorption of intermediates. {A figure is presented} Selectivity analysis by the reaction path method was used to determine the relative rates of each kinetic step in the above network. Absolute rate data are also provided. © 1978.