The Reactivity of Primary Free Radicals and Radical Ions,Mass Transfer,and Electrosorption—The Fundamental Factors for Selectivity in Electrochemical Syntheses of Organic Compounds

In many cases the electrolytic synthesis of organic compounds is rather unselective. This is because the primary radical ions and/or radicals are very often so reactive that they are able to react competitively with several of the different species present in the electrolyte. The aim is to increase the selectivity by rationally altering the process parameters; this demands a knowledge, inter alia, of electrosorption effects and of the relationships between mass transfer and chemical reaction, at or in front of the electrodes (in the so-called reaction layer). Four examples will be used to illustrate this theme:

• 1 The anodic synthesis of triarylsulfonium salts,
• 2 The addition of anodically generated N₃-radicals to olefins, producing “monomeric” 1,2-diazides and “dimeric” 1,4-diazides,
• 3 The cathodic synthesis of optically active 1-(2-pyridyl)ethanol,
• 4 The synthesis of 1,2- and 1,4-diol ethers by anodic oxidation of vinyl compounds in alcoholic solutions.