Mass spectrometry (MS) has long served as the gas-phase laboratory for the investigation of solvent- and counter-ion free reactivity of ions and molecules. Using charge tags, MS is also able to manipulate otherwise neutral species such as radicals. However, a skepticism obscured the beauty of gas-phase ion chemistry since  the high vacuum was considered by many as an environment with no bridge to the 'real world' of solutions. But John Fenn came to our rescue with his Nobel Prize winning electrospray ionization (ESI) technique, by making ��the power and elegance of MS applicable to both gas-phase and solution ions'. ESI brought MS down to the 'real world' of solutions by 'fishing' solution ions directly into the gas phase. Further developments of a number of desorption/ionization ambient MS techniques such as Venturi-assisted easy ambient sonic-spray ionization (V-EASI-MS) have allowed us to acquire continuous MS snapshots of the dynamic ionic composition of reaction solutions. Examples of ESI-MS and V-EASI monitoring of solutions including those for reactions of seminal importance in synthetic chemistry such as the Heck, Morita Baylis-Hillman, Fujiwara, Ugi and Hantzsch multi-component reactions are given and the detailed information on (transient) intermediates and actual mechanisms of reactions are stressed. The data demonstrates another fruitful marriage of the �bird and the fish� and that MS currently offers a bridge with a myriad of previously unthinkable routes for us chemists to make our ions 'fly from earth to moon', and vice-versa, and to investigate chemical reactions at the molecular level with unsurpassed speed, selectivity, sensitivity, ease and, now, great flexibility. We can now run reactions in solution and go 'ion fishing' with ESI or one of the many ambient MS techniques currently available and use the unsurpassed abilities of MS to characterize the intercepted intermediates.

Electrospray ionization and ambient mass spectromety: Wings for reaction intermediates

247th National Meeting (2014)

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