Halogens, electrochemical removal

Electrochemical processes can be used for the reduction of many other functional groups. Halogen is removed, as in the reduction of 6-chloro-l-hexene to 1-hexene in 23% yield (in DMF).560 j-y] halides are similarly reduced electrochemically. 2-Chloroaniline, for example, was reduced to aniline in 85% yield. If the electrodes and solvent are changed reductive coupling can occur. 2 Elimination is possible in some cases.Epoxides are opened electrochemically, and hydrogen is often delivered to the more substituted carbon, as in the quantitative conversion of 566 to 567. Azides are reduced to the amine. ... 

The complexes of thiuram disulfide can be oxidized by an excess of halogens to products containing the bis(iminio)trithiolane dication (113).122 123 One of the sulfur atoms is removed as free sulfur or as sulfur halide. According to some reports the bis(iminio)tetrathiolane dication (114) also exists.124 In our investigations, however, we could not obtain any proof of this ion. The electrochemical literature about the oxidation of thiuram disulfide is also contradictory.125,126 Apart from the trithiolane ion a dithietane ion (115) is prepared by oxidation of dimethylformamide with bromine.127 As far as we know, no other disulfide can be oxidized to an analogous dication. 

The electrochemical cleavage of C-halogen bonds allows to remove one halogen atom from polyhalogenated compounds selectively, to introduce C=C double bonds, and to produce organometallic compounds. Some examples from the patent literature are summarized below ... 

Another possible application of electrochemical reactors for urine treatment is the removal of micropollutants such as pharmaceutical residues. Depending on the characteristics of the micropollutants, direct oxidation at the anode [33] or reduction at the cathode (e.g., for the removal of halogenated organic compounds such as trihalo-methanes, [34]) can be a suitable process. 

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