Using Parahydrogen to Hyperpolarize Amines, Amides, Carboxylic Acids, Alcohols, Phosphates and Carbonates

Hyperpolarization turns weak NMR and MRI responses into strong signals so normally impractical measurements are possible. We use parahydrogen here to rapidly hyperpolarize appropriate 1H, 13C, 15N and 31P responses of analytes such as NH3 and important amines such as phenylethylamine, amides such as acetamide, urea and methacrylamide, alcohols spanning methanol through octanol and glucose, the sodium salts of carboxylic acids such as acetic acid and pyruvic acid, sodium phosphate, disodium adenosine 5’triphosphate and sodium hydrogen carbonate. The associated signal gains are used to demonstrate it is possible to collect informative single-shot NMR spectra of these analytes in seconds at the micromole level in a 9.4 T observation field. To achieve these wide ranging signal gains, we first employ the Signal Amplification By Reversible Exchange (SABRE) process to hyperpolarize an amine or ammonia and then employ their exchangeable NH protons to relay polarization into the analyte without changing its identity. We found the 1H signal gains reach as high as 650-fold per proton, while for 13C, the corresponding signal gains achieved in a 1H-13C refocused INEPT experiment exceed 570-fold and those in a direct detected 13C measurement 400-fold. Thirty one examples are described to demonstrate the applicability of this technique.