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. Author manuscript; available in PMC: 2020 May 23.
Published in final edited form as: J Phys Chem C Nanomater Interfaces. 2019 Apr 19;123(20):12827–12840. doi: 10.1021/acs.jpcc.9b02041

Figure 2.

Figure 2.

(a) Reaction scheme of pairwise addition of p-H2 to vinyl 1-13C-acetate in CD3OD followed by polarization transfer to 13C nuclei (HA and HB are two atoms from the same p-H2 molecule, cat. = [Rh(NBD)(dppb)]BF4). (b) Reaction scheme of the competing process of norbornadiene hydrogenation with p-H2. (c) 1H NMR spectrum acquired after 1H ALTADENA hyperpolarization of ethyl acetate with 15 s p-H2 bubbling duration. (d) Corresponding thermal 1H NMR spectrum acquired after relaxation of hyperpolarization (multiplied by a factor of 512). ε1H = 3750, P1H = 8.6% (8.1% at 85% p-H2 fraction). Note that spectra (c) and (d) were acquired on a 7.05 T NMR spectrometer. (e) 13C NMR spectrum acquired after 13C hyperpolarization of ethyl 1-13C-acetate using MFC at near 0 μT magnetic field. (f) Corresponding thermal 13C NMR spectrum acquired after relaxation of hyperpolarization (multiplied by a factor of 512). ε13C = 3560, P13C = 2.75% (4.2% at 85% p-H2 fraction). (g) Dependence of P13C (at 85% p-H2 fraction) of ethyl 1-13C-acetate on magnetic field used in MFC experiments (red squares – data points obtained with the [Rh(NBD)(dppb)]BF4 catalyst prepared from [Rh(NBD)2]BF4 and dppb, blue circles – data points obtained with the commercial [Rh(NBD)(dppb)]BF4 catalyst).