Hyperpolarization of [13C]formate using parahydrogen

Abstract

Sodium [¹³C]formate was successfully hyperpolarized using parahydrogen-induced polarization by means of side-arm hydrogenation (PHIP-SAH). Allyl [¹³C]formate was hyperpolarized using homogeneous hydrogenation of the corresponding unsaturated precursor (propargyl [¹³C]formate) in acetone-d₆ with parahydrogen. The observed proton polarization was estimated as 16.6 ± 0.6 % while achieving 80 % chemical conversion. The ¹H-to-¹³C polarization transfer was performed using magnetic field cycling. The highest observed polarization for ¹³C nuclei was estimated as 1.7 ± 0.2 % and was obtained at 250 nT polarization transfer magnetic field. We demonstrate that the ¹³C hyperpolarization is retained during the hydrolysis of allyl [¹³C]formate and hyperpolarized sodium [¹³C]formate was produced with P_13C of 0.4 ± 0.1 %.