  Nuclear magnetic resonance (NMR) spectroscopy provides detailed information
pertaining to dynamic processes through line-shape changes, which have been
traditionally limited to equilibrium conditions. However, there is a wealth of
information to be gained by studying chemical reactions under off-equilibrium
conditions -- e.g., in states that arise upon mixing reactants that
subsequently undergo chemical changes -- and in monitoring the formation of
reaction products in real time. Herein, we propose and demonstrate a
time-resolved kinetic NMR experiment that combines rapid mixing techniques,
continuous flow, and single-scan spectroscopic imaging methods, leading in
unison to a new 2D spectro-temporal NMR correlation which provides high-quality
kinetic information of off-equilibrium dynamics. These kinetic 2D NMR spectra
possess a spectral dimension conveying with high resolution the individual
chemical sites, correlated with a time-independent, steady-state spatial axis
that delivers unique information concerning temporal changes along the chemical
reaction coordinate. A comprehensive description of the kinetic and
spectroscopic features associated to these spectro-temporal NMR analyses is
presented, factoring in the rapid-mixing, the flow and the spectroscopic NMR
imaging. An experimental demonstration of this method's novel aspects was
carried out using an enzymatically catalyzed reaction, leading to site- and
time-resolved kinetic NMR data that are in excellent agreement with control
experiments and literature values.
