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Temperature effects on the 1H1H, 1H19F and 1919F coupling constants of fluorobenzene and 1,2-difluorobenzene

✍ Scribed by Sirpa Suntioinen; Ursula Weber; Reino Laatikainen

Publisher: John Wiley and Sons
Year: 1993
Tongue: English
Weight: 276 KB
Volume: 31
Category: Article
ISSN: 0749-1581
DOI: 10.1002/mrc.1260310419

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✦ Synopsis

Abstract

The ^1^H NMR spectra of fluorobenzene and 1,2‐difluorobenzene were measured in acetonitrile‐d~3~ and cyclohexane‐d~12~ at four temperatures to study the temperature dependence of ^1^H^1^H, ^1^H^19^F and ^19^F^19^F coupling constants. In acetonitrile‐d~3~ the ^5^J(F,H) coupling constant of fluorobenzene decreases by 5%, the ^5^J(H,H) coupling increases by 0.5% and all other couplings decrease by less than 1% when the temperature increases from 283 to 333 K. In cyclohexane‐d~12~ the change in ^5^J(F,H) for fluorobenzene is much smaller than in acetonitrile‐d~6~; the other changes are normally slightly smaller than in acetonitrile‐d~5~. The changes for 1,2‐difluorobenzene are generally of the same order as those for fluorobenzene.

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