Dechlorination of chloroaromatics by electrocatalytic reduction over palladium-loaded carbon felt at room temperature

The selective dechlorination of various chloroaromatics in water-MeOH mediu m containing trifluoroacetic acid and tetraalkylammonium salts was successf ully performed over Pd-loaded carbon felt cathode at room temperature. The reactivities of 2,4-dichlorophenyl derivatives varied in the order: 2,4-dic hlorotoluene < 2,4-dichlorophenol less than or equal to 2,4-dichloroanisole less than or equal to 2,4-dichlorobenzoic acid < 2,4-dichlorophenoxyacetic acid < 2,4-dichlorophenethyl alcohol. For 2,4-dihaloanisoles, the ease of reductive cleavage of C-X (X=halogen) bond was as follows: F << Cl < Br. Fo r monochlorobiphenyls, the dechlorination and product recovery efficiencies were remarkably affected by tetraalkylammonium cations of different size. The reaction scheme for the selective electrocatalytic dehalogenation of ha loaromatics over Pd-loaded felt cathode was proposed. (C) 1999 Elsevier Sci ence Ltd. All rights reserved.