Chemical Synthesis Accelerated by Paper Spray: The Haloform Reaction

In this laboratory, students perform a synthetic reaction in two ways: (i) by traditional bulk-phase reaction and (ii) in the course of reactive paper spray ionization. Mass spectrometry (MS) is used both as an analytical method and a means of accelerating organic syntheses. The main focus of this laboratory exercise is that the same ionization source can be operated to perform chemical analysis or to accelerate synthesis. More specifically, students explore the effect on reaction progress of operating in one of two modes of paper spray ionization. The modes relate to droplet size that changes as the solvent is depleted from the paper over time. The online mass spectral data for the two modes allow students to see the differences that small changes to spray conditions can have on the MS of a reaction mixture, allowing transition from traditional analysis to accelerated chemical synthesis by simply allowing the paper to partially dry. Chemical analysis and accelerated synthesis can be performed sequentiall...