US EPA

8717109 

Journal Article 

2D 19F/19F NOESY for the assignment of NMR spectra of fluorochemicals 

Battiste, JL; Jing, N; Newmark, RA 

2004 

Yes 

Journal of Fluorine Chemistry
ISSN: 0022-1139
EISSN: 1873-3328 

125 

9 

1331-1337 

English 

10.1016/j.jfluchem.2004.03.011 

WOS:000223811000010 

Two-dimensional (2D) NMR is an invaluable technique for the complete analysis and assignment of chemical structures. Although 19F/19F COSY experiments are routinely used for assignments in perfluorochemicals, interpretation can be difficult because four-bond (4JFF) coupling constants are typically 5-10-fold larger than vicinal (3JFF) coupling constants. Furthermore, the dependence of long range coupling constants on stereochemistry is not always known. Fluorine-fluorine NOESY correlations represent an enhancement in the arsenal of 2D 19F NMR experiments. The NOESY and COSY spectra of 2,2,3,3,4,4,4-heptafluorobutanol and a telomeric perfluorochemical iodide show that COSY identifies the 1,4-fluorine interactions whereas NOESY identifies the vicinal fluorine atoms. The combined experiments have been used to unambiguously assign all of the fluorines in a mixture of cis - and trans -perfluoro-1,3-dimethylcyclohexane and in a substituted perfluorotetrahydrofuran. 2004 Elsevier B.V. All rights reserved. 

19 F; Assignment; Fluorochemicals; Perflourodimethylcyclohexane