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Electrolysis of chlorinated and polycyclic aromatics | |
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Modification of organic compounds by electrochemical methods has found less application as compared with inorganic (technical) electrochemical processes. They exhibit however, apparent advantages as against conventional methods. In principle, reagents have not to be used in stoichiometric amounts and, therefore, by- and waste-products are minimized. This is due to the fact that, strictly speaking, the electrons supplied by the electrodes are the only reagents. We have succeeded in finding out experimental conditions on a laboratory scale which allow to remove largely the chlorine content of chlorinated benzenes, naphthalenes,[1] biphenyls, dibenzofurans,[2] certain dibenzodioxins and polychlorinated oligocyclic insecticides, e.g. Mirex®[3] or Thiodane®[3] by an electrolysis procedure. In this way, the toxicity of these notorious xenobiotics is significantly reduced.[4,5] Chlorinated toluenes, phenolethers, and phenols are partially dehalogenated by electroreduction. - In order to achieve a better selectivity and on account of ist general advantages we also successfully use the indirect electrolysis method with nickel complexes as mediators.[6] - In addition, carboxylation of chlorinated arenes through electrolyses with sacrificial magnesium anodes in presence of carbon dioxide is applied.[7] Moreover, we have performed experiments with polycyclic aromatic hydrocarbons (PAH), another class of toxic and carcinogenic compounds. Partial hydrogenolysis of the aromatic ring is possible by electroreduction.[8] The dechlorination project is performed in cooperation with Prof. W. Francke at our institute and Prof. P. Fortnagel at the department of biology. These investigations are supported by the BMBW and the DFG (SFB 188).
References:
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[1] |
J. Voss, E. Waller, P. Kränke, J. Prakt. Chem., 1998, 340, 430-436. |
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[2] |
E. Waller, Elektrochemische Enthalogenierung polychlorierter Naphthaline sowie Elektroreduktion monochlorierter Dibenzofurane, Dissertation, Univ. Hamburg, 1997. |
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[3] |
J. Gassmann, J. Voss, G. Adiwidjaja, Z. Naturforsch. 1996, 51b, 417-420. |
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[4] |
J. Voss, Electrochemical Dehalogenation of Chlorinated Aromatics and Aliphatics - A Contribution to the Degradation of Xenobiotics; in Novel Trends in Electroorganic Synthesis (Ed. S. Torii), Kodansha, Tokyo, 1995. |
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[5] |
J. Voss, E. Waller, Elektrochemische Enthalogenierung von Mischungen chlorierter Aromaten in Ölmatrices, Hamburger Berichte 10; Neue Techniken der Bodenreinigung (Hrsg. R. Stegmann), Economica Verlag, Bonn, 1996, 65-73. |
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[6] |
D. Nünnecke, J. Voss, Acta Chem. Scand. 1999, 53, 824-829. |
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[7] |
D. Golinske, J. Voss, G. Adiwidjaja Collect. Czech. Chem. Commun.2000, 65, 862-880. |
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[8] |
S. Anowski, J. Voss, J. Prakt. Chem.1996, 338, 337-344. |
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[9] |
J. Voss, M. Altrogge, D. Golinske, O. Kranz, D. Nünnecke, D. Petersen, E. Waller. In: Treatment of Contaminated Soils (Ed. R. Stegmann). Springer Verlag, Berlin, Heidelberg, New York, 2000, in press. |
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