TY - JOUR
T1 - Multidimensional NMR characterization of perfluorinated monomer and its precursors
AU - Zhang, Bo
AU - Li, Linlin
AU - Mikeš, František
AU - Koike, Yasuhiro
AU - Okamoto, Yoshiyuki
AU - Rinaldi, Peter L.
N1 - Funding Information:
We thank The Ohio Board of Regents and The National Science Foundation (CHE-0341701 and DMR-0414599) for funds used to purchase the NMR instrument used in this work. We wish to thank The National Science Foundation (DMR-0905120) for research support. We thank S. Stakleff, V. Dudipala and M. Guo of the University of Akron Magnetic Resonance Center who maintain the instrument used in this work. The syntheses and characterizations of compounds reported here were supported by the Japan Society for the Promotion of Science (JSPS) through its “Funding Program for World-Leading Innovative R&D on Science and Technology(FIRST Program)”.
PY - 2013/3
Y1 - 2013/3
N2 - Perfluorinated monomer (perfluoro-2-methylene-4,5-dimethyl-1,3-dioxolane), its precursor (perfluoro-2,4,5-trimethyl-1,3-dioxolane-2-carboxylic acid), as well as their hydrocarbon precursor (methyl 2,4,5-trimethyl-1,3-dioxolane-2- carboxylate), were prepared and studied by 1D- and advanced 2D NMR techniques. For both perfluorinated compounds, the structures of their possible isomers were proven by 2D NMR spectroscopy. Due to the large 19F spectral window, this study used selective versions of the correlation spectroscopy (COSY) and nuclear Overhauser effect spectroscopy (NOESY) experiments to provide better resolution and sensitivity. In addition, a new variation of the gradient heteronuclear single quantum coherence spectroscopy (gHSQC) sequence was successful for observing two-bond 19F13C correlations. Compared with the gradient heteronuclear multiple bond correlation spectroscopy (gHMBC) spectrum, the 2JFC gHSQC spectrum is greatly simplified due to the absence of splittings caused by multi-quantum coherence. Quantitative 1H or 19F 1D NMR was used to confirm the resonance assignments and to calculate the ratio of isomers. The configurational compositions of perfluorinated compounds and their hydrocarbon precursor support the idea that fluorination by elemental fluorine is a free radical process.
AB - Perfluorinated monomer (perfluoro-2-methylene-4,5-dimethyl-1,3-dioxolane), its precursor (perfluoro-2,4,5-trimethyl-1,3-dioxolane-2-carboxylic acid), as well as their hydrocarbon precursor (methyl 2,4,5-trimethyl-1,3-dioxolane-2- carboxylate), were prepared and studied by 1D- and advanced 2D NMR techniques. For both perfluorinated compounds, the structures of their possible isomers were proven by 2D NMR spectroscopy. Due to the large 19F spectral window, this study used selective versions of the correlation spectroscopy (COSY) and nuclear Overhauser effect spectroscopy (NOESY) experiments to provide better resolution and sensitivity. In addition, a new variation of the gradient heteronuclear single quantum coherence spectroscopy (gHSQC) sequence was successful for observing two-bond 19F13C correlations. Compared with the gradient heteronuclear multiple bond correlation spectroscopy (gHMBC) spectrum, the 2JFC gHSQC spectrum is greatly simplified due to the absence of splittings caused by multi-quantum coherence. Quantitative 1H or 19F 1D NMR was used to confirm the resonance assignments and to calculate the ratio of isomers. The configurational compositions of perfluorinated compounds and their hydrocarbon precursor support the idea that fluorination by elemental fluorine is a free radical process.
KW - 1,3-Dioxolanes
KW - Fluorinated monomers
KW - Fluorination
KW - Fluorine 1D and 2D NMR
KW - Mechanism of fluorination
KW - Multiple-bond gHSQC
KW - NOESY
KW - Perfluorinated polymers
KW - Perfluoro compounds
KW - Selective version of COSY
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U2 - 10.1016/j.jfluchem.2012.12.008
DO - 10.1016/j.jfluchem.2012.12.008
M3 - Article
AN - SCOPUS:84873736071
SN - 0022-1139
VL - 147
SP - 40
EP - 48
JO - Journal of Fluorine Chemistry
JF - Journal of Fluorine Chemistry
ER -