Efficient Batch-Mode Parahydrogen-Induced Polarization of Propane

We report on a simple approach for efficient NMR proton hyperpolarization of propane using the parahydrogen-induced polarization (PHIP) technique, which yielded approximate to 6.2% proton polarization using approximate to 80% parahydrogen, a record level achieved with any hyperpolarization technique for propane. Unlike in previously developed approaches designed for continuous-flow operation, where reactants (propene and parahydrogen) are simultaneously loaded for homogeneous or heterogeneous pairwise addition of parahydrogen, here a batch-mode method is applied: propene is first loaded into the catalyst-containing solution, which is followed by homogeneous hydrogenation via parahydrogen bubbling delivered at approximate to 7.1 atm. The achieved nuclear spin polarization of this contrast agent potentially useful for pulmonary imaging is approximately two orders of magnitude greater than that achieved in the continuous-flow homogeneous catalytic hydrogenation, and a factor of 3-10 more efficient compared to the typical results of heterogeneous continuous-flow hydrogenations.