Tsuyu Raymond Chen, G. Dryhurst
Feb 10, 1983
Citations
0
Influential Citations
16
Citations
Journal
Journal of Electroanalytical Chemistry
Abstract
Abstract Voltammetry of 7,9-dimethyluric acid in aqueous solution at a pyrolytic graphite electrode shows that two oxidation peaks are formed. Peak Ia is a 2 e electrooxidation giving a very unstable quinonoid cation. This rapidly hydrates in a phosphate-catalyzed reaction giving a tertiary alcohol which in turn undergoes a ring contraction to 1-carbohydroxy-2,4-dimethyl-2,4,6,8-tetraaza-3,7-dioxo-5-ene-bicyclo-(3.3.0)-octane. The latter is again unstable and hydrates and decarboxylates giving 1,3-dimethylallantoin as the final product. Peak IIa is due to a Kolbe-type 2 e electrooxidation of 1-carbohydroxy-2,4-dimethyl-2,4,6,8-tetraaza-3,7-dioxo-5-ene-bicyclo-(3.3.0)-octane to give a very reactive carbonium ion and CO2. The former species is rapidly hydrated giving 1-hydroxy-2,4-dimethyl-2,4,6,8-tetraaza-3,7-dioxo-5-ene-bicyclo-(3.3.0)-octane, a new compound which has been isolated and characterized by spectral, chemical and electrochemical methods.