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^(13)C nuclear magnetic resonance spectroscopy. Determination of carbon-fluorine couplings

Weigert, Frank J. and Roberts, John D. (1971) ^(13)C nuclear magnetic resonance spectroscopy. Determination of carbon-fluorine couplings. Journal of the American Chemical Society, 93 (10). pp. 2361-2369. ISSN 0002-7863. doi:10.1021/ja00739a001.

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One-, two-, three-, and four-bond carbon-fluorine coupling constants have been observed for a series of substituted fluorobenzenes. The one-bond coupling constants in the para derivatives are proportional to the fluorine chemical shifts, but a similar correlation shows considerable scatter for the meta derivatives and is invalid for the ortho derivatives. The carbon-fluorine coupling constants in fluorobenzene are JCF= -245.3, JCCF= +21.0, JCCGF) = + 7.7, and Jccccr = +3.3 Hz. Consistent explanations of the substituent effects on the long-range coupling constants have not been found. All the carbons in l-fluoronaphthalene are coupled to the fluorine with magnitudes of 0.6 to 250 Hz. The fluorine in 2-fluoronaphthalene is coupled to only six carbons, presumably those in the same ring as the fluorine. The carbon-fluorine coupling constants in n-hexyl fluoride are JCF = - 166.6, JCCF = +19.9, and JcccF= 5.25 Hz. The one-bond carbon-fluorine couplings in cyclic geminal difluorides vary with ring size. The fluorine substituent effect on the chemical shifts of carbons y to the fluorine is discussed in terms of proposed steric perturbation mechanisms.

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Additional Information:© 1971 American Chemical Society. Received June 18, 1970. Supported in part by the National Science Foundation. Some of the data in this paper were reported in preliminary paper: F. J. Weigert and J. D. Roberts,J. Amer. Chem. Soc., 91,4940 (1969). (2) National Science Foundation Predoctoral Fellow, 1965-1968.
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NSF Predoctoral FellowshipUNSPECIFIED
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Caltech Gates and Crellin Laboratories4060
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Official Citation: Carbon-13 nuclear magnetic resonance spectroscopy. Determination of carbon-fluorine couplings John D. Roberts and Frank J. Weigert Journal of the American Chemical Society 1971 93 (10), 2361-2369 DOI: 10.1021/ja00739a001
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:60995
Deposited By: Ruth Sustaita
Deposited On:13 Oct 2015 21:24
Last Modified:10 Nov 2021 22:42

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