The hydrophobic effect in aqueous solutions of nonelectrolytes. I. Self-interactions of alkylureas |
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Authors: | Guido Barone Giuseppina Castronuovo Vittorio Crescenzi Vittorio Elia Eugenio Rizzo |
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Institution: | (1) Istituto Chimico, University of Naples, 80134 Naples, Italy;(2) Istituto Chimico, University of Rome, 00185 Rome, Italy |
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Abstract: | In order to clarify some aspects of the hydrophobic interactions, the enthalpies of dilution of monoethylurea, 1,3-dimethylurea,
and 1,3-diethylurea have been determined calorimetrically at 25°C. The calorimetric data, expressed in terms of excess enthalpy,
permit the evaluation of the pair and triplet interaction coefficients. The analyses of these and of the analogous coefficientsg
xx andg
xxx, derived from osmotic data, indicate a driving force favorable to the interactions among the hydrated solute molecules. Nevertheless,
the positive values of theh
xx andh
xxx coefficients seem to suggest that the source of the effect is a rearrangement of the water molecules rather than a direct
association of the solute molecules. There are evidences of a strict correlation between the enthalpic and the entropic effects.
Preliminary data were presented at the International Conferences on Chemical Thermodynamics at Baden (1973) and Montpellier
(1975). The experimental part was carried out at the Istituto Chimico of the University of Trieste.
To whom correspondence should be addressed. |
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Keywords: | Hydrophobic interactions hydrophobic hydration alkylureas aqueous solutions excess functions |
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