Figure 3.
(a) Diagram of PEP to PLAC conversion using automated PHIP polarizer. (b) pH optimization of PEP (5 mM) in phosphate buffer (25 mM) using Rh(I) catalyst (5.3 mM) at 55 ± 2 °C. (c) pH optimization of PEP (30 mM) in phosphate buffer (30 mM) using Rh(I) catalyst (5.3 mM) in the pH range of interest. Rh(I) catalyst performs several hydrogenation cycles using 30 mM PEP, Figure 1. The reaction temperatures were 68 ± 1 °C (red trace) and 55 ± 1 °C (blue trace). (d) Final pH (of solutions exiting PHIP polarizer) as a function of the starting pH (solutions entering PHIP polarizer) of solutions used in (c). All hydrogenations were performed at ∼7 atm of H2 gas partial pressure during an ∼5 s reaction time.