Ring hydrolysis in the electro-oxidation of pyrrolidone analogues

Upon oxidation in acetonitrile, pyrrolidone analogues, namely pyrrolidone, methyl-pyrrolidone, ethyl-pyrrolidone and N-vinyl pyrrolidone, afford thin organic films which can be analyzed by X-ray photoelectron spectroscopy. On e common singular feature is noted in the XPS spectra: the advent of a very high energy Cls peak (288.9 eV), indicating the formation of a molecular s tructure with a carbon atom in an unusually electronegative environment. Co nsidering the recently proposed reaction mechanisms for the oxidation of py rrolidone analogues, a theoretical study is carried out: several molecular structures are proposed, on which very accurate calculations of core-electr on binding energies are performed using the density functional theory. On c omparison with the complete experimental spectrum, it is proposed that this peculiar high-energy peak stems from the opening of the pyrrolidone ring t o yield carboxylic acid groups. (C) 2001 Elsevier Science B.V. All rights r eserved.