Vapor Pressures of the Fluorinated Telomer Alcohols-Limitations of Estimation Methods

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• 作者：Naomi L. Stock ; David A. Ellis ; Lisa Deleebeeck ; Derek C. G. Muir ; and Scott A. Mabury
• 刊名：Environmental Science & Technology
• 出版年：2004
• 出版时间：March 15, 2004
• 年：2004
• 卷：38
• 期：6
• 页码：1693 - 1699
• 全文大小：134K
• 年卷期：v.38,no.6(March 15, 2004)
• ISSN：1520-5851

文摘

The influence of the unique, physical properties of poly-and perfluorinated chemicals on vapor pressure wasinvestigated. Vapor pressures of a suite of fluorinatedtelomer alcohols (FTOHs) (CF₃(CF₂)_nCH₂CH₂OH, where n =3, 5, 7, or 9) were measured using the boiling pointmethod and ranged from 144 to 992 Pa. Comparison ofexperimental and literature values indicate that perfluorocarbons (CF₃(CF₂)_nCF₃, where n = 0-6) and fluorinatedtelomer alcohols have vapor pressures equal to or greaterthan that of their hydrogen analogues. These chemicallycounterintuitive results can be explained by the uniquegeometry of poly- and perfluorinated chemicals-in particularthe stiff, helical perfluorinated chain and the significantintramolecular hydrogen bonding of the FTOHs. The majorityof models investigated for the estimation of vapor pressuredid not compensate for this unique geometry andconsistently underpredicted the vapor pressures of theFTOHs. Calculation of partitioning constants using bothexperimental and estimated vapor pressures indicate thatboth the Antoine and Modified Grain models, and to alesser degree the Mackay model, are insufficiently accuratefor estimating the vapor pressures of the FTOHs,particularly the longer chain FTOHs. Future models shouldconsider parameters such as geometry, strength, andlocation of intramolecular hydrogen bonds and other functiongroups in the molecule in order to improve vapor pressureestimation accuracy. It appears likely that the uniquemolecular geometry of the FTOHs influences not only theirvapor pressure but also other physical properties andhence environmental fate and dissemination.