Abstract
It is demonstrated that hyperpolarized catalyst-free gases can be produced in a gas–liquid biphasic hydrogenation with parahydrogen using a dissolved catalyst and gaseous reactants. The reaction product is shown to return to the gas phase while retaining a substantial level of nuclear spin hyperpolarization, providing a complete separation of the hyperpolarized substance from the catalyst. The approaches based on biphasic and heterogeneous hydrogenations are shown to be suitable for producing hyperpolarization in a continuous mode. Subsequent gas dissolution can be added to yield solutions of hyperpolarized substances. Extension to a broader range of hyperpolarized substances is shown to be possible based on the hydrogenation of liquid vapors.