Complete dechlorination of DDT and its metabolites in an alcohol mixture using NaOH and Pd/C catalyst.

DDT (1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane) was dechlorinated in 2-propanol/methanol (99:1v/v) by means of stoichiometric reaction with NaOH and subsequent catalytic dechlorination over Pd/C catalyst. When DDT was treated with a molar excess of NaOH ([NaOH]/[DDT]=9) in the alcohol mixture at room temperature, DDT disappeared within 15min. The reaction of DDT produced an equimolar amount of HCl to yield DDE (1,1-bis(4-chlorophenyl)-2,2-dichloroethylene). The produced DDE was successfully dechlorinated to a chlorine-free product (1,1-diphenylethane, 97% yield) by addition of Pd/C to the alkaline solution and heating at 40 degrees C for 4h. DDD (1,1-bis(4-chlorophenyl)-2,2-dichloroethane) was also dechlorinated to 1,1-diphenylethane in a similar manner. Possible dechlorination pathways for DDT, DDE, and DDD were investigated by observation of the partially dechlorinated intermediates by means of gas chromatography/mass spectrometry (GC/MS).