Catalytic dechlorination of aromatic chlorides with noble-metal catalysts under mild conditions: approach to practical use

The Pd-catalyzed hydrodechlorination of chlorophenols in aqueous solutions under mild conditions: A promising approach to practical use in wastewater

“…So, NaCl, produced in the dechlorination procedure of 4-CP, would cover on the surface of active sites of Pd/C and block the pores of carbon support in organic solvents and the reaction would gradually become more and more difficult to carry out. Ukisu et al [20] in their studies on hydrogenation of aromatic chlorides over Rh-Pt/C have also observed the activity of the catalyst gradually decreased due to accumulation of sodium chlorides on its surface and water could wash away these salts.…”

“…When 5% isopropanol was present in water, the reaction was accelerated and the rate was about 8.0 × 10 −2 mmol/min. In liquid phase, Pd catalyst could lead isopropanol to dissociate to provide proton (Scheme 2) [20]. In 5% isopropanol-aqueous solution, besides molecular hydrogen, isopropanol was also the other source of hydrogen.…”

“…In other words, the source of hydrogen was enough for the hydrogenation; therefore the dechlorination rate was quicker when 5% isopropanol was present in water. The catalytic hydrodechlorination of aromatic chlorides has ever been reported using isopropanol as the source of hydrogen [20]. For methanol and ethanol, they were one of the components of the reaction medium, and did not participate in the hydrodechlorination of 4-CP.…”

“…Chlorides derived from the dechlorination reaction were easy to result the catalysts in the deactivation in organic solvent systems [19][20][21]. We have reported the heterogeneously catalytic hydrodechlorination of aromatic halides with hydrogen gas over Pd/C in liquid phase.…”

Dechlorination of hexachlorobenzene using ultrafine Ca–Fe composite oxides

“…They include biodegradation [3][4][5], photocatalytic oxidation [6,7] and catalytic hydrodechlorination [8][9][10][11][12][13][14][15][16][17]. In general, chemical methods have been by far the most studied ones.…”