Salting-in of alcohols in aqueous solutions by tetraalkylammonium bromides at the freezing temperature |
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Authors: | Jacques E Desnoyers Gérald Perron Sylvain Léger Byron Y Okamoto Terrence H Lilley Robert H Wood |
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Institution: | (1) Department of Chemistry, Université de Sherbrooke, J1K 2R1 Sherbrooke, Quebec, Canada;(2) Department of Chemistry, University of Delaware, 19711 Newark, Delaware |
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Abstract: | The freezing-point depression of the ternary systems tetraalkylammonium bromides-t-butanol-water for the first five homologs of R4NBr was measured. In the case of Bu4NBr, the effect of size of the alcohol (methahol ton-butanol) was also investigated. From the corresponding freezing-point data for the binary systems the apparent salting constants
were calculated. The true salting constantsk
s were obtained by extrapolation to infinite dilution. These are all very close to zero at the freezing temperature. From the
corresponding thermochemical data the temperature dependence ofk
s was calculated, and above 5°C all the R4NBr salts int-butanol; the salting-in increases with temperature and with the size of the hydrophobic cations. The scaled-particle theory
is at present the only one which can account semiquantitatively for the temperature dependence of the salting-in effect.
On leave of absence from Chemistry Department, The University, Sheffield S3 7HF, England
To whom correspondence should be addressed. |
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Keywords: | Salting-in freezing-point depression alcohols tetraalkyl-ammonium bromides |
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