Fig. 10: rINEPT and DEPT in the case of J = 3 Hz.
From: Nuclear spin polarization of lactic acid via exchange of parahydrogen-polarized protons
13C polarization during rINEPT (blue) and DEPT (orange) with J = 3 Hz for the fully coupled spin system (a, as in Fig. 5) and where all couplings, except the ones between the labile protons and carbon, were 0 (b). For the fully coupled system, the dynamics are affected by the other couplings in the molecule. DEPT achieved almost three times higher polarization as rINEPT. This suggests that other, more efficient sequences maybe found that take all couplings into account. For the simplified system (e.g. a tertiary alcohol), the expected behavior is observed, suggesting that the polarization was transferred from the labile proton despite of the exchange.
