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Heterogeneous Parahydrogen Pairwise Addition to Cyclopropane
Author(s) -
Salnikov Oleg G.,
Kovtunov Kirill V.,
Nikolaou Panayiotis,
Kovtunova Larisa M.,
Bukhtiyarov Valerii I.,
Koptyug Igor V.,
Chekmenev Eduard Y.
Publication year - 2018
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201800690
Subject(s) - spin isomers of hydrogen , hyperpolarization (physics) , propane , chemistry , cyclopropane , induced polarization , nuclear magnetic resonance , nuclear magnetic resonance spectroscopy , hydrogen , stereochemistry , organic chemistry , ring (chemistry) , physics , engineering , electrical engineering , electrical resistivity and conductivity
Hyperpolarized gases revolutionize functional pulmonary imaging. Hyperpolarized propane is a promising emerging contrast agent for pulmonary MRI. Unlike hyperpolarized noble gases, proton‐hyperpolarized propane gas can be imaged using conventional MRI scanners with proton imaging capability. Moreover, it is non‐toxic odorless anesthetic. Furthermore, propane hyperpolarization can be accomplished by pairwise addition of parahydrogen to propylene. Here, we demonstrate the feasibility of propane hyperpolarization via hydrogenation of cyclopropane with parahydrogen. 1 H propane polarization up to 2.4 % is demonstrated here using 82 % parahydrogen enrichment and heterogeneous Rh/TiO 2 hydrogenation catalyst. This level of polarization is several times greater than that obtained with propylene as a precursor under the same conditions despite the fact that direct pairwise addition of parahydrogen to cyclopropane may also lead to formation of propane with NMR‐invisible hyperpolarization due to magnetic equivalence of nascent parahydrogen protons in two CH 3 groups. NMR‐visible hyperpolarized propane demonstrated here can be formed only via a reaction pathway involving cleavage of at least one C–H bond in the reactant molecule. The resulting NMR signal enhancement of hyperpolarized propane was sufficient for 2D gradient echo MRI of ∼5.5 mL phantom with 1×1 mm 2 spatial resolution and 64×64 imaging matrix despite relatively low chemical conversion of cyclopropane substrate.