Elucidating the Association of Water in Wet 1-Octanol from Normal to High Temperature by Near- and Mid-Infrared Spectroscopy

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• 作者：Francesca Palombo ; Thierry Tassaing ; Marco Paolantoni ; Paola Sassi ; Assunta Morresi
• 刊名：Journal of Physical Chemistry B
• 出版年：2010
• 出版时间：July 22, 2010
• 年：2010
• 卷：114
• 期：28
• 页码：9085-9093
• 全文大小：430K
• 年卷期：v.114,no.28(July 22, 2010)
• ISSN：1520-5207

文摘

Near- (NIR) and mid-infrared (MIR) absorption spectra of pure and water-saturated 1-octanol were measured along the liquid−gas coexistence curve from ambient temperature and pressure up to 300 °C and 10 MPa. Density of the mixture as a function of temperature was assessed by spectral analysis in the NIR region. Two distinct regimes of temperature were identified in the evolution of solvent-subtracted spectra: at normal conditions and up to 180 °C, water is organized in multimeric H-bonded aggregates, while at higher temperature, mainly dimers and monomers exist. Water−water and alcohol−alcohol H-bonding interactions play a major role in wet octanol at low temperature, with resulting microheterogeneity and water segregation at a molecular level; on the other hand, water−alcohol interactions are relevant at higher temperature, as also revealed by the estimated density. At low temperature, water dissolved in octanol shows features which are comparable to those of interfacial water obtained by vibrational sum frequency (VSF) spectroscopy, while at high temperature the spectra generally reproduce those of water in the supercritical phase. Overall spectral assignment was supported by ab initio calculations at the MP2 level on small water clusters.