Air-and moisture-sensitive compounds pose handling difficulties for chemists requiring mass spectrometric analysis. A simple pressurized sample infusion (PSI) system for electrospray ionization mass spectrometry using a Schlenk flask is presented, which allows straightforward one-off analyses as well as continuous reaction monitoring at any temperature up to the boiling point of the solvent.

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Negative-ion electrospray ionisation mass spectrometry with an anionic phosphine ligand enables detection of key intermediates in the Sonogashira reaction. MS/MS techniques are used to generate a Hammett plot for the key reductive elimination step.

Keeping an eye on all the players: The combination of bulky phosphonium tags and pressurized sample infusion transforms electrospray ionization mass spectrometry into a tool capable of producing dense data on the relative concentrations of all components of a catalytic reaction, such as the palladium‐catalyzed coupling of an aryl iodide with phenylacetylene (see graph).

Palladium(0) complexes facilitate many catalytic transformations that begin with the oxidative addition of a halobenzene. The ligation state of the palladium during this reaction is a vexing issue, owing to the inherent difficulty of isolating reactive, coordinatively unsaturated metal complexes. By isolating them in the gas phase in an ion‐trap mass spectrometer, the reactivity of mono‐ and bisligated palladium complexes can be directly compared, and the former proved to be several orders of magnitude more reactive towards halobenzenes. Calculations of barrier heights for the oxidative addition led to additional experiments, which demonstrated that although the reaction proceeded to completion for iodobenzene, the reaction was slower for bromobenzene and progressed only as far as an ion–molecule adduct for chloro‐ and fluorobenzene.