Chloroform d

Samples for PHIP−SAH and −HOT: 10 μl of TVOA (synthesized according to a protocol described below) or vinyl acetate (CAS 108‐05‐4, Merck) was dissolved in 600 μL of acetone‐d₆ or chloroform‐d (Deutero GmbH) yielding a 100 mmol/L concentration. For PHIP experiments the catalyst [1,4‐Bis(diphenylphosphino)butane(1,5‐cyclooctadiene)rhodium(I) tetrafluoroborate] [1] (CAS: 79255‐71‐3, Strem Chemicals) was added to reach a concentration of 5 mmol/L. chloroform‐d and acetone‐d₆ were dried by pouring it through a 3 cm column (ID=5 mm) of basic aluminium oxide powder and magnesium sulfate respectively directly before preparation of the samples. Both powders were dried overnight at 120°. Note, that even after drying, the residual HDO concentration was determined to approx. 1 mM. These samples were flushed by pH₂ to produce hyperpolarization in the following stage.
Samples for reference NMR spectra: NMR spectra of the following compounds dissolved in chloroform‐d or acetone‐d₆ were measured at concentrations of 10–100 mM: vinyl acetate (CAS: 108‐05‐4), ethyl‐acetate (CAS: 141‐78‐6), triethyl orthoacetate (CAS: 78‐39‐7), acetaldehyde (CAS: 75‐07‐0), 2‐chloroethanol (CAS: 107‐07‐3), ethyl alcohol (CAS: 64‐17‐5). All compounds were purchased from Merck. These samples and the corresponding spectra were used to assign the products of the TVOA hydrogenation.