Abstract
The rates of oxidation by cerium (IV) of several substituted benzylic acids (unsubstituted, 2,2′-dichloro, 4,4′-dichloro, 4,4′-dimethyl, 4,4′-dimethoxy, and 4,4′-dinitro) to the corresponding benzophenones have been studied spectrophotometrically in aqueous H2SO4, aqueous HClO4-HOAc, and acetonitrile. The rates are much slower in H2SO4 than in the other two media, probably because of heavy sulfato complexation of cerium(IV). The px as of the various acids were determined potentiometrically. The Hammett p values in acetonitrile and HClO4-HOAc media, derived from correlations with several sets of σ constants and with the newly determined pKas, are about -0.7 and -0.35 in the two media, respectively. These values rule out the possibility of positive charge development at the benzhydrilic carbon, at or prior to the rate-determining step. Instead, a mechanism involving free (?) radicals is proposed. © 1977, American Chemical Society. All rights reserved.
Recommended Citation
S. B. Hanna and S. A. Sarac, "Metal-Ion Oxidative Decarboxylations. 10. Substituent Effects In The Cerium(IV)-Benzilic Acids Reaction," Journal of Organic Chemistry, vol. 42, no. 12, pp. 2069 - 2073, American Chemical Society, Jun 1977.
The definitive version is available at https://doi.org/10.1021/jo00432a006
Department(s)
Chemistry
International Standard Serial Number (ISSN)
1520-6904; 0022-3263
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2023 American Chemical Society, All rights reserved.
Publication Date
01 Jun 1977
