ELECTROCHEMICAL THERMOSPRAY MASS-SPECTROMETRY - ANODIC-OXIDATION OF N,N-DIALKYLANILINES

The coupling of an electrochemical cell on-line with a thermospray mas s spectrometer can be used for the identification of reaction products . The objective of this study was to demonstrate the performance of el ectrochemical thermospray mass spectrometry (ETMS). The anodic oxidati on of N,N-dialkylanilines in 0.1 M NH4OAc was studied. Structural info rmation on the products were obtained by measurements in D2O-based ele ctrolyte solution. The first step was the oxidation of dialkylaniline to radical cations. Recombination of the radical cations formed benzid ine as the chief product. In the main side reaction the radical cation s were deprotonated at the C-H acid cc-carbon atom to radicals. A part of these radicals was oxidised at the electrode to immonium ions. By follow up reactions, such as hydrolysis, dealkylation, oxidation and r ecombination with monomeric radical cations, dimers were formed. Repea ting the side reaction, these dimers reacted to give trimers and highe r oligomers. A scheme of the different reaction pathways is presented. (C) 1998 Elsevier Science S.A. All rights reserved.