Online mechanistic investigations of catalyzed reactions by electrospray ionization mass spectrometry: A tool to intercept transient species in solution

During the last two decades there has been considerable growth in the development of electrospray ionization mass spectrometry (ESI-MS) as a practical method for studying reaction mechanisms. This tool allows interception and characterization of several key intermediates, either as transient species or as protonated/deprotonated forms of neutral species. Reaction pathways shown by ESI-MS(/MS) have been probed by gas-phase ion/molecule reactions, and expanded mechanisms have been elaborated based on mass spectrometric data. The successful application of EST-MS in revealing, elucidating, and helping to consolidate proposed mechanisms of organic reactions is emphasized. This is meant to serve as a foundation for future investigations in this rapidly developing area of research. Outstanding features and advantages of ESI-MS make it one of the most suitable tools for the fast screening of intermediates directly from solution; it has significantly increased the chemical information available to organic chemists. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).