Photoelectrochemical pK Scale for weak CH-acids

The method of laser photoelectron emission from metals in electrolyte solutions has been used to measure the rate constants w₃ for the electrochemical reduction of simple organic radicals R to carbanions R^–. The following empirical rule has been established: the changes in the standard redox potential E° for R^–/R in series of organic radicals are equal to the changes in the potential corresponding to individual values of w₃. On the basis of this rule and the value of E° for CH₃ ^–/CH₃ E° values were obtained for C₂H₅, n-C₃H₇, n-C₄H₉, CH₂OH, CH₃CHOH, (CH₃)₂COH, CH₂Cl, CHF₂, CHFCl, CHCl₂, CF₂Cl, CFCl₂, CF₃, CCl₃, C₆H₅, C₆Cl₅, and a scale of pK for the CH acids conjugate to R^–. Consideration is given to the nature of the changes in E° and p^K on passing from aqueous solutions to solutions in water-dioxane mixtures and in acetonitrile.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1508–1514, July, 1990.