Acta Crystallographica Section E: Crystallographic Communications (Apr 2019)

Crystallographic and spectroscopic characterization of 4-nitro-2-(trifluoromethyl)benzoic acid and 4-nitro-3-(trifluoromethyl)benzoic acid

  • George L. Diehl III,
  • Lisa Je,
  • Joseph M. Tanski

DOI
https://doi.org/10.1107/S2056989019003979
Journal volume & issue
Vol. 75, no. 4
pp. 524 – 528

Abstract

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The title compounds, both C8H4F3NO4, represent two isomers of nitro trifluoromethyl benzoic acid. The compounds each contain a nitro functionality para to the carboxylic acid group, with the trifluoromethyl substituent ortho to the acid group in the 2-isomer and ortho to the nitro group in the 3-isomer. The regiochemistry with respect to the trifluoromethyl group results in steric interactions that rotate the carboxylic acid group or the nitro group out of the aromatic plane in the 2- and 3-isomer, respectively. Each molecule engages in intermolecular hydrogen bonding, forming head-to-tail dimers with graph-set notation R22(8) and donor–acceptor hydrogen-bonding distances of 2.7042 (14) Å in the 2-isomer and 2.6337 (16) in the 3-isomer. Recrystallization attempts did not yield untwinned crystals.

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