Electrochemical chlorination

J. J. Kaczui and D. W. Cawlfield, "New Electrochemical Chlorine Dioxide Generation Technology," in Ref. 64. 

The Olin Corporation has developed an electrochemical chlorine dioxide generator technology that safely and conveniently produces aqueous chlorine free solutions of chlorine dioxide at chlorite molar conversion efficiencies of 95% or better [221-224]. The chlorine dioxide is produced by direct oxidation of sodium chlorite, Fig. 21. The electrochemical C102 generator system is shown in Fig. 22. 

Kaczur JJ, Cawlfield DW, New electrochemical chlorine dioxide generation technology, in Ref [45]... 

Cawlfield DW, Kaczur JJ (Olin Corp) (1991) Electrochemical chlorine dioxide generator, PCT Int Appl WO 91 09,990 Chem Abstr 115 (1991) 169055a... 

Electrocatalysis of electrochemical chlorine evolution from Ru02-coated titanium anodes rests on the same grounds according to the so-called Krasil shchikov mechanism, which is schematically described by the reactions (8a) and (8b) for anodic chlorine evolution (9-/2) ... 

Chlorocyclohexanone can be prepared by chlorinating cyclohexanone in glacial acetic acid as the solvent,4 by passing chlorine into a mixture of cyclohexanone 5 or cyclohexanol6 and water in the presence of powdered calcium carbonate, by the electrochemical chlorination of cyclohexanone in hydrochloric acid,7 by the action of monochlorourea in acetic acid on the ketone,8 and by the oxidation of 2-chlorocyclohexanol.9... 

A regio- and chemoselective ene-type chlorination of isoprenoids has been realized by electrolysis in a CH2C12/H20—NaCl—(Pt) two-phase system. The electrochemical chlorination of dehydrolinalyl acetate 35 forms the ene-type chlorinated product 43 in 91 % yield (Scheme 3-14)641. The product selectivity of the ene-type chlorination is... 

Electrochemical chlorination, bromination, and iodination of heterocycles 90M120. 

Electrochemical chlorination of cyclohexene in nitromethane to yield initially a-chloro-cyclohexanone is more effective in presence of a small amount of water386. Product distribution is also a function of the potential applied387. 

Radiolysis was also used to graft metal nanoparficles onto anodes or cathodes involved in the electrochemical chlorine-soda process. Bimetallic nanoparficles Pt-Ru and Ni-Ru grafted onto bulk metal electrodes (Ti or Ni) displayed a remarkable electro-catalytic efficiency for this reaction and a drastic decreasing of the overpotential was observed for Pt-Ru alloys (2 1 atomic ratio). 

The observed products on the above electrodes are in contrast to other conventional electrochemical chlorinations of olefins, where carbon favored glycol formation 341-343). The discrepancy may result from differences in contact patterns and cell designs. 

Literature on electrochemical chlorination of organic compounds was exhaustive represented in monograph, published recently [2]. Possible ethylene chlorination mechanism in concentrated hydrochloric acid solutions that results in producing 1,2-diohloroethane was also discussed there in detail. 

While chlorinating of benzene homologues, the main question is the place of chlorine binding aromatic nucleus or the side chain. In the case of chemical chlorination these processes are mastered well [2]. It was necessary to determine the conditions of selective chlorination of either the nucleus or the side chain in the case of electrochemical chlorination. 

The influence of the current density on the processes under consideration is of two kinds. On the one hand, increase in the current density enhances the productivity of the cell. On the other hand, at the sharp increase in the i-ate of electrochemical chlorine evolution aromatic molecule have no enough time to bond it. Atmospheric emission of chlorine that takes place results in both decrease of the current efficiency and onvirogment pollution. At the current density being equal 1-1,5 kA/m the current efficiency of the chlorinated alkylaromatio compounds was 30%, while that of the monooh-lorbenzene was 10%. ... 

Barashkov NN, Eiseinberg D, Eiseinberg S (2010) Electrochemical chlorine-free AC disinfection of water contaminated with Salmonella typhimurium bacteria. Russ J Electrochem 46 306-311... 

Electrochemical treatment could also be used to disinfect urine before it is used as a fertilizer. The most likely process is electrochemical chlorine formation. However, indirect electrooxidation via chlorine can lead to unwanted by-products such as chlorate, perchlorate, and halogenated organic compounds [12]. More research is needed to determine whether and how the formation of unwanted by-products can be prevented. 

Torii S, Uneyama K, Nakai T, Yasuda T (1981) An electrochemical chlorinative ene-type reaction of isoprenoids. Tetrahedron Lett 22 2291-2294... 

An electrochemical chlorination of isoprenoid-type alkenes in a methylene chloride-water-sodium chloride system to produce allylic chlorides has been reported [equation (9)] presumably Cr is generated by anodic oxidation as the reactive species. The selectivity of chlorination is affected markedly by the conditions, but trisubstituted terminal double bonds of the type shown in equation (9) are the most reactive. 

Chen, R. Y., V. Trieu, A. R. Zeradjanin et al. 2012. Microstructural impact of anodic coatings on the electrochemical chlorine evolution reaction. Phys. Chem. Chem. Phys. 14 7392-7399. 

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