Efficient Preparation of Hyperpolarized Aqueous Succinate from the Para-Hydrogenation & Hydrolysis of Maleic Anhydride

Francesca Reineri¹, Alessandra Viale¹, Silvano Ellena¹, Tommaso Boi¹, Roberto Gobetto¹, Silvio Aime¹

Para-Hydrogen Induced Polarization (PHIP) has been recently exploited for the preparation of hyperpolarized ¹³C contrast agents for MRI. For the observation of large PHIP effects the use of homogeneous hydrogenation catalysts is generally required. The catalyst and (if present) the organic solvent must then be removed in order to obtain non-toxic formulations of the hyperpolarized agents. Here we report the para-hydrogenation of an unsaturated activated substrate, maleic anhydride, in chloroform, followed by rapid hydrolysis to form a water-soluble derivative, succinic acid, which can be extracted in water to yield a pure aqueous solution of the hyperpolarized molecule.