Association of nonvolatile globular carboxylic acids in gas phase as studied by means of FTIR spectrometry

V. Šablinskas, B. Mikulskiene, L. Kimtys

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Abstract

The thermodynamics of the hydrogen bonding of pivalic and 3- chloropivalic acids in gas phase was studied with FTIR spectroscopy and quantum chemistry (semi-empirical and ab initio) calculations. All theoretical methods suggest the existence of the only one stable conformer (C(s)) of 3-chloropivalic acid. The heat of formation of the cyclic dimers of pivalic and 3-chloropivalic acids in gas phase was calculated from experimental data and found to be of 64.7 ± 1.4 kJ/mol and 61 ± 3 kJ/mol, respectively. The results obtained indicate that the substitution of one hydrogen in the CH3 group of pivalic acid by chlorine has no measurable influence on the heat of the cyclic dimerization. However, 3-chloropivalic acid does not form the high temperature orientationally disordered solid phase (plastic crystal) in contrast to pivalic acid. Different molecular shapes (different globularity) of the investigated acids could be the main reason for different orientational behaviour of the investigated acids.

Original languageEnglish
Pages (from-to)263-269
Number of pages7
JournalJournal of Molecular Structure
Volume482-483
DOIs
Publication statusPublished - May 25 1999
Externally publishedYes

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Keywords

  • Carboxylic acids
  • Hydrogen bonding
  • Plastic crystals
  • Vibrational spectrometry

ASJC Scopus subject areas

  • Structural Biology
  • Organic Chemistry
  • Physical and Theoretical Chemistry
  • Spectroscopy
  • Atomic and Molecular Physics, and Optics

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