COUPLED CHEMISTRY REVISITED IN THE TENTATIVE CATHODIC ELECTROPOLYMERIZATION OF 2-BUTENENITRILE

2-Methyl 2-propenenitrile (methacrylonitrile) and 2-butenenitrile (cro tononitrile) are vinylic molecules which differ only in the position o f a methyl group on the double bond. By combining gas chromatography c oupled to chemical ionization mass spectrometry, steric exclusion chro matography and infra-red spectroscopy, along with quantum chemistry ba sed calculations of standard Gibbs energy changes of plausible reactio ns, we demonstrate that the protons of the methyl group in crotononitr ile are acidic in anhydrous acetonitrile, while those of methacrylonit rile are not. In this way, we bring a definite explanation to the fact that methacrylonitrile forms homogeneous films of polymethacrylonitri le (PMAN) on a working electrode subjected to a cathodic polarization in anhydrous acetonitrile, while crotononitrile does not. (C) 1998 Els evier Science S.A. All rights reserved.