Journal of Thermal Analysis and Calorimetry

, Volume 107, Issue 3, pp 1301–1306 | Cite as

Activation energy (ΔG*), enthalpy (ΔH*), and entropy (ΔS*) of some indoles and certain of their binary mixtures

  • Mohan T. Hosamani
  • Narasimha H. Ayachit
  • D. K. Deshpande


Thermodynamic parameters, like, change of activation energy for dipole orientation (ΔG*), enthalpy (ΔH*), and entropy (ΔS*) of activation in the case of binary-, ternary-, etc. mixtures of polar molecules in pure liquid phase or in dilute solution phase in a non polar solvent helps in drawing certain quantitative conclusions regarding their relaxation behavior as to whether a single component is responsible for observed microwave absorption or a cooperative phenomenon (average) by all the dipoles of the mixture contribute to it. Dielectric relaxation behavior of polar molecules in a non-polar solvent, or mixtures of these substances at different microwave frequencies and over a range of temperatures and concentrations give a method of determining these quantities. Such an experimental investigation on verity of systems is necessary to draw quantitative conclusions regarding the system of the molecules which are not studied so as to examine if the results obtained are in favor or against the general conclusions already arrived at, in other systems. With this in view, systematic dielectric measurements in a range of temperatures are carried out at a single microwave frequency on a single weight fraction in benzene of the four substituted indoles, namely, 5-Bromoindole, 5-Fluoroindole, 2,3-Dimethylindole, 2,5-Dimethylindole and on binary (1:1) mixtures of 2,5-Dimethylindole + 5-Bromoindole and 2,3-Dimethylindole + 5-Fluoroindole in benzene as solvent at different temperatures. The results are presented and discussed.


Dielectric relaxation Enthalpy Activation energy 



The authors (NHA and MTH) acknowledge the help and encouragement shown by their respective principals and managements in carrying out this work.


  1. 1.
    Coffey WT. Dielectric relaxation: an overview. J Mol Liq. 2004; 114:5–25 and references thereinGoogle Scholar
  2. 2.
    Kollengodu-Subramanian S, McKenna GB. A dielectric study of poly(vinylacetate) using apulse probe technique. J Therm Anal Calorim. 2010;102:477–84.Google Scholar
  3. 3.
    Mészáros P, Funk DB. Measurement of moisture in grain at extreme temperatures with high frequency dielectric method. J Therm Anal Calorim. 2005;82:253–60.Google Scholar
  4. 4.
    Mano J, Lanceros-Méndez S, Nunes A, Dionísio M. Temperature measurements in dielectric measurements. J Therm Anal Calorim. 2001;65:37–49.Google Scholar
  5. 5.
    Sannaninganavar FM, Ayachit NH, Deshpande DK. On the effect of temperature on the dielectric relaxation time of some phenols and certain of their binary mixtures. J Mol Liq. 2006;124:124–6.Google Scholar
  6. 6.
    Fattepur RH, Hosamani MT, Deshpande DK, Mehrotra SC. Dielectric relaxation and structural study of aniline–methanol mixture using picosecond time domain reflectometry. J Chem Phys. 1994;101:9956–60.Google Scholar
  7. 7.
    Vasan ST, Ayachit NH, Deshpande DK. On the effect of temperature on the dielectric relaxation time of some benzene derivatives and certain of their binary mixtures. Phys Chem Liq. 2006;44:513–9.Google Scholar
  8. 8.
    Vasan ST, Ayachit NH. Dielectric behavior of some mesogenic-non-mesogenic- and organic molecules. J Mol Liq. 2007;135:38–41.Google Scholar
  9. 9.
    Fattepur RH, Hosamani MT, Deshpande DK, Mehrotra SC. Dielectric relaxation and related studies of 4-ethylphenol-methanol mixtures using time domain reflectoraetry. Pramana J Phys. 1995;44:33–44.Google Scholar
  10. 10.
    Vasan ST, Sannaninganavar FM, Ayachit NH, Deshpande DK. Dielectric relaxation in relation to viscosity of some organic molecules and some of their binary mixtures. J Mol Liq. 2007;135:115–9.Google Scholar
  11. 11.
    Ayachit NH, Sannaninganavar FM, Deshpande FM. Viscoelastic studies of some phenols from dielectric measurements. Phys Chem Liq. 2007;45:513–9.Google Scholar
  12. 12.
    Ayachit NH, Sannaninganavar FM, Deshpande DK. On the viscoelastic and dielectric behavior of two alcohols and their binary mixture. Phys Chem Liq. 2010 (in press).Google Scholar
  13. 13.
    Schallamach A. Dielectric relaxation and viscosity of long-chain dipolar liquids. Trans Faraday Soc. 1946;42:495–501.Google Scholar
  14. 14.
    Madan MP. Relaxation processes of quinoline, isoquinoline, and their mixtures. Can J Phys. 1980;58:20–4.Google Scholar
  15. 15.
    Awasti A, Rastogi M, Sukla JP. Relaxation and associative aspects of X… HO bond complexes. Phys Chem Liq. 2003;41:337–45.Google Scholar
  16. 16.
    Khirade PW, Choudhari A, Shindhe JB, Helumbe SN, Mehrotra SC. Temperature dependent dielectric relaxation of 2-ethoxyethanol, ethanol, and 1-propanol in dimethylformamide solution using the time-domain technique. J Solut Chem. 1999;28:1031–8.Google Scholar
  17. 17.
    Takaaki S, Buchner R, Fernandez S, Chiba A, Kunz W, Choudhari A. Dielectric relaxation spectroscopy of aqueous amino acid solutions: dynamics and interactions in aqueous glycine. J Mol Liq. 2005;117:93–8.Google Scholar
  18. 18.
    Koga Y, Tukahasni H, Higasi K. Dielectric relaxation and molecular structure. VII. Structure of the molecules of diphenylene dioxide type. Bull Chem Soc Jpn. 1973;24:3359–63.Google Scholar
  19. 19.
    Abd-El Messieh SL. Effect of solvent viscosity on the dielectric relaxation of some acetophenone derivatives. J Mol Liq. 2003;105:37–51.Google Scholar
  20. 20.
    Whiffin DH, Thompson HW. Sources of radiation and absorption cells. Trans Faraday Soc. 1945;41:180–8.Google Scholar
  21. 21.
    Roberts S, Von Hippel A. A new method for measuring dielectric constant and loss in the range of centimeter waves. J Appl Phys. 1946;17:610–6.Google Scholar
  22. 22.
    Dekin TW, Works CN. Microwave dielectric measurements. J Appl Phys. 1947;18:789–97.Google Scholar
  23. 23.
    Gopal Krishna KV. A method of measuring the dipole moment and relaxation time from microwave measurements. Trans Faraday Soc. 1946;53A:767–72.Google Scholar
  24. 24.
    Hennelly EJ, Heston WM, Smith CP. Microwave absorption and molecular structure in liquids. III. Dielectric relaxation and structure in organic halides. J Am Chem Soc. 1948;70:4102–11.Google Scholar
  25. 25.
    Brain FM, Smith CP. Microwave absorption, molecular structure in liquids. IX. Measurement in organic halides at 10-cm wavelength. J Chem Phys. 1952;20:4097–102.Google Scholar
  26. 26.
    Magee MD. Dielectric relaxation time, a non-linear function of solvent viscosity. J Chem Soc. 1974;70:929–38.Google Scholar
  27. 27.
    Debye P. Part I. Dielectric constant. Energy absorption in dielectrics with polar molecules. Trans Faraday Soc. 1934;30:679–84.Google Scholar
  28. 28.
    Hill NE. The ‘universal dielectric response’ in simple liquids. J Phys C. 1980;13:1121–2.Google Scholar
  29. 29.
    Barlow AJ, Erginsav A, Lamb J. Viscoelastic relaxation in liquid mixtures. Proc R Soc. 1969;A309:473–96.Google Scholar
  30. 30.
    Chitoku K, Higasi K. Dielectric relaxation and molecular structure. I Bull Chem Soc (Jpn). 1963;36:1064–71.Google Scholar
  31. 31.
    Krishnaji SL, Srivastava DN. Dielectric relaxation studies in liquids at microwave frequencies and viscoelastic relaxation behavior of the solvents. J Chem Phys. 1970;52:940–5.Google Scholar
  32. 32.
    Verstakov ES, Yastemsskii PS, Kessler YM, Goncharov VV, Kokavin VV. Dielectric and structural properties of aqueous solutions of dimethylformamide and dimethyl sulfoxide. J Struct Chem. 1980;21:636–9.Google Scholar
  33. 33.
    Kremer F, Schönhals A. Broadband dielectric spectroscopy. Berlin: Springer; 2002.Google Scholar
  34. 34.
    Buchner R. Dielectric spectroscopy of solutions. In: Samios J, V.A. Durov VA, editors. Novel approaches to the structure and dynamics of liquids: experiments, theories and simulations, NATO Science Ser. II: Mathematics, Physics and Chemistry, vol 133. Dordrecht: Kluwer; 2004. pp. 265–88.Google Scholar
  35. 35.
    Smyth CP. Dielectric polarization and relaxation. Annu Rev Phys Chem. 1966;17:433–53.Google Scholar
  36. 36.
    Sakellaridis P, Hinopoulos B. Dielectric relaxation behavior of some primary, secondary alcohols in heptane solutions. J Phys D Appl Phys. 1972;5:1815–21.Google Scholar

Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2011

Authors and Affiliations

  • Mohan T. Hosamani
    • 1
  • Narasimha H. Ayachit
    • 2
  • D. K. Deshpande
    • 3
  1. 1.Department of PhysicsP C Jabin Science CollegeHubliIndia
  2. 2.BVB College of Engineering and TechnologyHubliIndia
  3. 3.Karnataka UniversityDharwadIndia

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