Journal of Solution Chemistry

, Volume 22, Issue 8, pp 695–706 | Cite as

Dilution enthalpies of alkanols in concentrated aqueous solutions of urea at 25°C

  • M. Abbate
  • G. Barone
  • G. Borghesani
  • G. Cirillo
  • C. Giancola
  • M. Remelli


Enthalpies of dilution of some aliphatic alcohols were determined at 25°C in aqueous 7M urea solutions by flow microcalorimetry. The excess enthalpies were expressed as power expansion series in molalities referred to 1 kg of constant composition urea-water mixture. This urea-water mixture was utilized throughout as a mixed solvent. The values of the second enthalpic virial coefficients were all found to be positive and generally lower than the corresponding values in water. Large differences were encountered, as in water, by comparing normal and branched isomeric propanols and butanols. For one system it was possible to measure the third coefficients, which were also positive. The second enthalpic coefficients were found to increase with the molecular weight of the alkanols. These facts suggest that in the presence of a large concentration of urea, the excess enthalpies are mainly determined by apolar interactions. This is surprising and potentially rich in consequences for a better understanding of the interactions among amino acid residues distantly situated in the primary sequences but topologically near in the loops of globular proteins. An analysis, carried out using the Savage-Wood additivity group method, shows that the enthalpic contributions (that appear to play a crucial role in water in making the polar interaction to be favorable) become essentially unfavorable in urea-water solvent. The hypothesis that the peptide-peptide interactions are prevented by the preferential solvation of urea is also discussed.

Key words

Alkanols urea weak interactions aqueous solutions group additivity 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    W. Kauzmann,Adv. Protein Chem. 14, 1 (1959).Google Scholar
  2. 2.
    G. Nemethy and H. A. Scheraga,J. Chem. Phys. 36, 3382 (1962).Google Scholar
  3. 3.
    G. Nemethy and H. A. Scheraga,J. Chem. Phys. 36, 3401 (1962).Google Scholar
  4. 4.
    G. Nemethy and H. A. Scheraga,J. Phys. Chem. 63, 1773 (1962).Google Scholar
  5. 5.
    D. Eagland, inWater, A Comprehensive Treatise, F. Franks, ed., Vol. 4 (Plenum Press, New York, 1975), p.482.Google Scholar
  6. 6.
    J. J. Kozak, W. S. Knight, and W. Kauzmann,J. Chem. Phys. 48, 675 (1968).Google Scholar
  7. 7.
    H. L. Friedman and C. V. Krishnan,J. Solution Chem. 2, 119 (1973).Google Scholar
  8. 8.
    F. Franks, M. D. Pedley, and S. Reid,J. Chem. Soc. Faraday Trans. I,72, 1359 (1976).Google Scholar
  9. 9.
    J. J. Savage and R. H. Wood,J. Solution Chem. 5, 733 (1976).Google Scholar
  10. 10.
    J. E. Desnoyers, G. Perron, L. Avédikian, and J.-P. Morel,J. Solution Chem. 5, 631 (1976).Google Scholar
  11. 11.
    D. Hallén, S.-O. Nilsson, W. Rothschild, and I. Wadsö,J. Chem. Thermodyn. 18, 429 (1986).Google Scholar
  12. 12.
    G. Perron and J. E. Desnoyers,J. Chem. Thermodyn. 13, 1105 (1981).Google Scholar
  13. 13.
    E. Lange and H.-G. Markgraf,Z. Elektrochem. 54, 73 (1950).Google Scholar
  14. 14.
    W. Dimmling and E. Lange,Z. Elektrochem. 55, 322 (1951).Google Scholar
  15. 15.
    R. B. Cassel and R. H. Wood,J. Phys. Chem. 78, 2465 (1975).Google Scholar
  16. 16.
    E. Lange and K. Möhring,Z. Elektrochem. 57, 660 (1953).Google Scholar
  17. 17.
    F. Franks,Phil. Trans. Royal Soc. B278, 33 (1977).Google Scholar
  18. 18.
    A. M. Clark, F. Franks, M. D. Pedley, and D. S. Reid,J. Chem. Soc. Faraday Trans. I 73, 290 (1977).Google Scholar
  19. 19.
    A. Ben NaimHydrophobic Interactions, (Plenum Press, New York, 1980).Google Scholar
  20. 20.
    D. B. Wetlaufer, S. K. Malik, L. Stoller, and R. L. Coffin,J Am. Chem. Soc. 86, 508 (1974).Google Scholar
  21. 21.
    N. Desrosier, G. Perron, J. G. Mathieson, B. E. Conway, and J. E. Desnoyers,J. Solution Chem. 3, 789 (1974).Google Scholar
  22. 22.
    N. R. Choudhury and J. C. Ahluwalia,J. Chem. Soc. Faraday Trans. I,77, 3119 (1981).Google Scholar
  23. 23.
    A. Ben-Naim and M. Yaacobi,J. Phys. Chem. 78, 170 (1974).Google Scholar
  24. 24.
    M. Abbate, G. Barone, G. Castronuovo, P. J. Cheek, C. Giancola, T.E. Leslie, and T. H. Lilley,Thermochem. Acta 173, 261 (1990).Google Scholar
  25. 25.
    G. Barone, G. Borghesani, C. Giancola, F. Pulidori, and M. Remelli,Thermochimica Acta 162, 241 (1990).Google Scholar
  26. 26.
    W. G. McMillan Jr. and J. E. Mayer,J. Chem. Phys. 13, 276 (1945).Google Scholar
  27. 27.
    G. Barone, P. Cacace, G. Castronuovo, and V. Elia,J. Chem. Soc. Faraday Trans. I 77, 1569 (1981).Google Scholar
  28. 28.
    G. Barone, G. Castronuovo, and V.Elia,Advances in Mol. Relax. Interact. Processes 23, 279 (1982).Google Scholar
  29. 29.
    T. H. Lilley in M. N. JonesBiochemical Thermodynamics 2nd edn. (Elsevier, London. 1988). Chap. I.Google Scholar
  30. 30.
    G. Barone and C. Giancola,Pure & Appl. Chem. 62, 57 (1990).Google Scholar
  31. 31.
    G. Borghesani, R. Pedriali, F. Pulidori, and I. Scaroni,J. Solution Chem. 15, 397 (1986).Google Scholar
  32. 32.
    G. Borghesani, R. Pedriali, and F. Pulidori,J. Solution Chem. 18, 289 (1989).Google Scholar
  33. 33.
    C. Cascella, G. Castronuovo, V. Elia, R. Sartorio, and S. Wurzburger,J. Chem. Soc. Faraday Trans. 86, 85 (1990).Google Scholar
  34. 34.
    S. Andini, G. Castronuovo, V. Elia, and L. Fasano,J. Chem. Soc., Faraday Trans. 86, 3567 (1990).Google Scholar
  35. 35.
    L. Ambrosone, S. Andini, G. Castronuovo, V. Elia, and G. Guarino,J. Chem. Soc. Faraday Trans. 87, 2989 (1991).Google Scholar
  36. 36.
    G. M. Blackbum, T. H. Lilley, and P. J. Milbum,J. Chem.Soc. Faraday Trans. I 82, 2965 (1986).Google Scholar
  37. 37.
    G. Borghesani, M. Remelli, and F. Pulidori,Thermochimica Acta 137, 165 (1988).Google Scholar
  38. 38.
    E. G. Finer, F. Franks, and M. J. Tait,J. Am. Chem. Soc. 94, 4424 (1972).Google Scholar
  39. 39.
    P. Cristinziano, F. Lelj, P. Amodeo, and V. Barone,Chem. Phys. Lett. 140, 401 (1987).Google Scholar
  40. 40.
    P. Cristinziano, F. Lelj, P. Amodeo, G. Barone, and V. Barone,J. Chem. Soc. Faraday Trans. I 85, 621 (1989).Google Scholar
  41. 41.
    G. Barone,Thermochim. Acta. 162, 17 (1990). See references quoted therein.Google Scholar

Copyright information

© Plenum Publishing Corporation 1993

Authors and Affiliations

  • M. Abbate
    • 1
  • G. Barone
    • 1
  • G. Borghesani
    • 2
  • G. Cirillo
    • 1
  • C. Giancola
    • 1
  • M. Remelli
    • 2
  1. 1.Department of ChemistryUniversity of Naples ‘Federico II’NaplesItaly
  2. 2.Department of ChemistryUniversity of FerraraFerraraItaly

Personalised recommendations