Separation of Anti-Phase Signals Due to Parahydrogen Induced Polarization via 2D Nutation NMR Spectroscopy.

The present work introduces a novel method for the selective detection of H NMR anti-phase signals caused by the pairwise incorporation of parahydrogen into olefins on noble-metal-containing catalysts. Via a two-dimensional (2D) nutation NMR experiment, the anti-phase signals of hyperpolarized H nuclei are separated due to their double nutation frequency compared to that of thermally polarized H nuclei. For demonstrating this approach, parahydrogen induced polarization (PHIP) was achieved via the hydrogenation of propene with parahydrogen on platinum-containing silica and investigated by in situ H MAS NMR spectroscopy under continuous-flow conditions, that is, the hydrogenation reaction was performed inside the magnet of the NMR spectrometer.