FTIR studies of intermolecular hydrogen bonding in halogenated ethanols.
The effect of halogen substitution on intermolecular hydrogen-bonding in ethanol is studied. Specifically, Fourier-transform infrared (FTIR) spectra of ethanol, 2,2,2-trifluoroethanol (TFE), and 2,2,2-trichloroethanol dissolved in carbon tetrachloride are reported as a function of temperature and concentration. The spectral intensities corresponding to monomer, dimer, and multimer formation are used to determine the effect of halogen substitution on intermolecular hydrogen-bonding. The enthalpy for dimerization was found to evolve from -4.2+/-0.3 kcal/mol in ethanol to -6.8+/-1.0 kcal/mol in TFE. An opposite trend was observed for multimer formation with enthalpies of -3.7+/-0.5 in ethanol and -2.1+/-1.4 kcal/mol in TFE. The majority of this evolution is assigned to the ability of ethanols to form intramolecular hydrogen bonds involving the hydoxyl proton and the halogen substituents.
Blainey
P C
PC
University of Washington, Department of Chemistry, Seattle 98195, USA.
Reid
P J
PJ
D019281:Dimerization; D000431:Ethanol / Q000737:chemistry*; D005023:Ethylene Chlorohydrin / Q000031:analogs & derivatives* / Q000737:chemistry*; D006860:Hydrogen Bonding; D017550:Spectroscopy, Fourier Transform Infrared; D014270:Trifluoroethanol / Q000737:chemistry*
D000431:Ethanol; D014270:Trifluoroethanol; D005023:Ethylene Chlorohydrin; C005849:2,2,2-trichloroethanol