Peter Tompe

Quantitative structure-electrochemistry relationships of α, β-unsaturated ketones

Abstract The half-wave potential ( E 1 2 ) of 26 substituted α,β-unsaturated ketones in non-aqueous acetonitrile were used in Hammett type quantitative structure-activity relationship (QSAR) analysis. A linear relationship between E 1 2 and the electronic substituent constant, σx and reaction constant grR was revealed for 17 substituted chalcones. Linear regression equations were calculated using only the sum of σx,para + σx,meta of all substituents. It was found that the production of the substituted 1,2-oxaphosphol-4-en in the redox reaction of the α,β-unsaturated ketones and trialkyl phosphite can be predicted from the E 1 2 values of the α,β-unsaturated ketones measured in nonprotic solvent. The E 1 2 values also give a linear correlation with the conversions of the starting ketones.

Electrochemical study of the oxidation of carbidopa and its determination using liquid chromatography with electrochemical detection

The electrochemical oxidation of carbidopa [(S)-(-)-2-(3,4-dihydroxybenzyl)-2-hydrazinopropionic acid monohydrate] was studied by linear sweep voltammetry, cyclic voltammetry, microcoulometry and preparative electrolysis. An ECCE mechanism with two-electron transfer, followed by two chemical reactions (decarboxylation and hydrolysis), were found, giving carbon dioxide, hydrazine and 3,4-dihydroxyphenylacetone. The final electrochemical step may be a reversible two-electron oxidation process which gives the o-quinoidal analogue of the latter. An analogous oxidation mechanism was found when carbidopa was oxidized with HBrCl 2 in hydroxychloric acid