NMR Flow Tube for Online NMR Reaction Monitoring

In this paper we describe the development of a 5 mm NMR flow tube that can be used in a standard 5 mm NMR probe, enabling the user to conduct experiments on flowing samples or, more specifically, on flowing reaction mixtures. This enables reaction monitoring or kinetic experiments to be conducted by flowing reaction mixtures from a reaction vessel to detection in the coil area of the NMR, without the need for a specialized flow NMR probe. One of the key benefits of this flow tube is that it provides flexibility to be used across a range of available spectrometers of varying magnetic field strengths with a standard 5 mm probe setup. The applicability of this flow tube to reaction monitoring is demonstrated using the reaction of p-phenylenediamine and isobutyraldehyde to form the diimine product.