| Autor: |
Peter Klaboe, D.H. Christensen, T. Tirgrimsen |
| Rok vydání: |
1974 |
| Předmět: |
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| Zdroj: |
Journal of Molecular Structure. 23:15-32 |
| ISSN: |
0022-2860 |
| DOI: |
10.1016/0022-2860(74)85052-0 |
| Popis: |
The infrared spectra of 2-chloro-3-fluoro- and 2-bromo-3-fluoro-1-propene as vapours and liquids were recorded in the region 4000–4050 cm −1 . Additional spectra of the amorphous and crystalline solids at −170 °C and of the liquids in polar and non-polar solvents were recorded between 4000 and 200 cm −1 . Raman spectra, including semi-quantitative polarization measurements of the liquids were obtained. Spectra were also recorded with the samples dissolved in polar and non-polar solvents, and unannealed as well as annealed crystalline solids were studied at −180 °C. Approximately 14 vibrational bands present in the spectra of the liquids, solutions and the glassy solids vanished in the infrared and Raman spectra of the crystals. From various criteria it can be concluded with certainty that the more polar ( gauche ) and less polar ( cis ) conformers were present in the crystalline chloro- and bromo- compounds, respectively. From infrared and Raman band intensities it was estimated that the conformational equilibrium in chlorofluoro-propene was highly displaced towards cis in the vapour, with both conformers approximately equally abundant in the liquid state (30 °C). For bromofluoro- propene the equilibrium was still further displaced towards the cis conformer. A striking similarity between the spectra of the two compounds was ob- served. The fundamental frequencies have been tentatively assigned and checked by force constant calculations. Dipole moments and relative stabilities of the conformers were estimated by a CNDO calculation. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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