Figure 3: Experimental setups and timetables showing the actuation of the magnetic valves.

Setup 1: The pH₂ reservoir was connected to the inlet of the reaction chamber via a pressure regulator (PR), valve V1, and a non-metallic check valve. V1 was opened for a period of t_pH2 to initialize the chemical reaction. The SOT sequence was executed after an additional delay (t_delay), resulting in a total hydrogenation time t_hydr. The outlet valve V2 was closed during the entire hydrogenation and hyperpolarization process. After signal detection, V2 was opened and the solution was flushed out from the reactor and caught in a water bath (blue). Setup 2 was identical to setup 1 but an additional valve (V3) was installed to bypass the reactor for equilibration of the pressure between in- and outlet. This valve was opened after t_pH2 for a period of t_bypass to stop the pH₂ injection and to prevent the formation of gas bubbles. When heteronuclear decoupling was required, decoupling was played out only during t_bypass.