Assignment of the Vibrations in the Near-Infrared Spectra of Phenol–OH(OD) Derivatives and Application to the Phenol–Pyrazine Complex

• Published in: Journal of molecular spectroscopy 1997-06, Vol.183 (2), p.245-249
• Main Authors: Rospenk, M., Leroux, N., Zeegers-Huyskens, Th
• Format: Article
• Language: English
• ISSN: 0022-2852; 1096-083X
• DOI: 10.1006/jmsp.1997.7284

The near-infrared spectra (7200–3800 cm−1) of seven phenols OH–OD (4-CH3, H, 4-Cl, 4-Br, 3-Br, 3,4-diCl, 3-5-diCl) are investigated at room temperature in carbon tetrachloride. The mid-infrared spectra of some phenol–OD have also been studied. Beside the first overtone of the ν(OH) stretching vibration, six absorptions disappear upon deuteration. The absorptions are assigned to combinations involving the ν(OH) stretching mode and aromatic ring vibrations, the ν(C–O) mode, or the δ(OH) mode. The anharmonicity and coupling constants are discussed. The isotopic ratio of the ν(OH) stretching fundamentals, of their first overtone, and the ratio of the anharmonicity constants are very insensitive to the nature of the phenol. The stability constants of complexes between phenols and base can be computed from several near-infrared absorptions and this is illustrated for the 3,5-dichlorophenol–pyrazine complex.