Electrochemical oxidation of organic compounds in fluorosulfuric acid—III. Voltammetric investigation of aromatic carboxylic acids and acylium ions

✍ Scribed by A.P. Rudenko; M.Ja. Zarubin; N.S. Barsheva; F. Pragst

• Publisher: Elsevier Science
• Year: 1983
• Tongue: English
• Weight: 600 KB
• Volume: 28
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(83)85128-7

✦ Synopsis

The anodic behavior of a series of substiruted benzoic acids la -1w and of the corresponding benzoylium ions r is investigated by cyclic voltammetry in fluorosulfuzacid at -76%. The acids are oxidized to cation radicals, the stability of which decreases with decreasing number ofalkyi substituents. As a subsequent reaction the functionalization of one of the methy groups to the fluorosulfonyloxymethyl group is found. After dissolving at room temperature the acids with one o-alkyl group are between 80 and 100 y0 and the acids with two o-alkyl groups are completely transformed into henzoylium ions 5+ which are between 450 and 560 mV more positively oxidized than the acid. The main reaction of the dicatlon radical formed is Ihe addition of SO,F-to the carbonylium C-atom. As the number of alkyl substituents decreases this reaction competes with the functionalization of a methyl group. The difference between the voltammetric data in HSO,F and acetonitrile is discussed in terms of a protonation of the benzoic acids and their oxidation products