When analytical and synthetic Chemists work together Reactions on the Track

A new technique, desorption electrospray ionization coupled to mass spectrometry (DESI-MS), has been used as a tool for reaction analysis. Charged droplets of a reagent are sprayed onto the catalyst, which has previously been deposited on a surface in front of a mass analyzer. The reaction starts as the droplets impact the catalyst on the surface and continues inside secondary microdroplets that are desorbed from the surface. These are directed toward the mass spec inlet. Using this technique, the very first milliseconds of a reaction can be observed. The first example describes the discovery of an extremely short-lived intermediate in a C-H amination reaction cycle. Another example describes how DESI-MS has been used to identify catalyst arrest mechanisms in ruthenium catalyzed C-H hydroxylation.