Exploration of reactional parameters for palladium-catalyzed cross-coupling reaction with thermal desorption-electrospray ionization mass spectrometry

Abstract

Thermal desorption-electrospray ionization/mass spectrometry (TD-ESI/MS), an ambient ionization mass spectrometric technique, was used to explore reactional parameters of a palladium-catalyzed cross-coupling reaction. TD-ESI/MS employed a thermal desorption unit to convert analytes from solution to gas phase. After which, the desorbed analytes reacted with the charged solvent species in an electrospray plume to form analyte ions prior to mass spectrometric detection. Since analytes are separated from the matrix before ionization, the composition of sample matrix will not affect the ionization efficiency of the analyte. With its simple sampling, easy operation, minimal sample preparation requirements, and rapid analytical workflow, TD-ESI/MS shows significant promise for rapid qualitative analysis and characterization of chemical compounds in ongoing chemical reactions. The time-resolved mass spectra provided detailed insights into the changes of chemical species throughout the reaction. This approach enables comprehensive exploration of the parameters involved in the reaction mechanisms, including the impacts of various reactional factors such as solvent type, electron-withdrawing or electron-donating group on the reactants, and substituent position of the reactants.

Keywords: Ambient ionization; Electrospray ionization; Reaction monitoring; Thermal desorption.