This review summarises the rarely used method of alternating current electrolysis for the synthesis of organic products. Different waveforms have been investigated which opens the possibility for further influence the outcome of the electrolysis by variation of the frequency as well as the highest peak current. In recent years alternating current electrolysis has been applied in increasingly more complex transformations. Especially the functionalisation of (hetero)arenes, functional group manipulation, metathesis reactions, and transition-metal-catalysed cross-coupling reactions were reported in recent years and the results of these and some other investigations are summarized in this review article.1 Introduction1.1 Waveforms1.2 Objectives1.3 Early Examples of the Optimisation of Alternating Current Electrolysis2 Recent Applications of Alternating Current Electrolysis for Organic Synthesis2.1 Substitution Reaction on Arenes2.2 Nitrogen–Sulfur Bond Formation and Sulfur–Sulfur Bond Metathesis2.3 Oxidation and Reduction2.4 Cross-Coupling Reactions2.5 Frequency Optimisation3 Conclusion

The first example for the electrochemical cisdichlorination of alkenes is presented. The reaction can be performed with little experimental effort by using phenylselenyl chloride as catalyst and tetrabutylammoniumchloride as supporting electrolyte, which also acts as nucleophilic reagent for the S N 2-type replacement of selenium versus chloride. Cyclic voltammetric measurements and control experiments revealed a dual role of phenylselenyl chloride in the reaction. Based on these results a reaction mechanism was postulated, where the key step of the process is the activation of a phenylselenyl chloride-alkene adduct by electrochemically generated phenylselenyl trichloride. Like this, different aliphatic and aromatic cyclic and acyclic alkenes were converted to the dichlorinated products. Thereby, throughout high diastereoselectivities were achieved for the cis-chlorinated compounds of > 95 : 5 or higher.