Production of Pure Aqueous C-Hyperpolarized Acetate by Heterogeneous Parahydrogen-Induced Polarization.

A supported metal catalyst was designed, characterized, and tested for aqueous phase heterogeneous hydrogenation of vinyl acetate with parahydrogen to produce C-hyperpolarized ethyl acetate for potential biomedical applications. The Rh/TiO catalyst with a metal loading of 23.2 wt % produced strongly hyperpolarized C-enriched ethyl acetate-1- C detected at 9.4 T. An approximately 14-fold C signal enhancement was detected using circa 50 % parahydrogen gas without taking into account relaxation losses before and after polarization transfer by magnetic field cycling from nascent parahydrogen-derived protons to C nuclei. This first observation of C PHIP-hyperpolarized products over a supported metal catalyst in an aqueous medium opens up new possibilities for production of catalyst-free aqueous solutions of nontoxic hyperpolarized contrast agents for a wide range of biomolecules amenable to the parahydrogen induced polarization by side arm hydrogenation (PHIP-SAH) approach.