J Solution Chem (2009) 38: 557–570 DOI 10.1007/s10953-009-9392-5 Dipole moments of Flourobenzene and its Mesogenic Derivative in 1,4-Dioxane and 1-Butanol Solutions A. Ghanadzadeh Gilani · A. Ranjkesh · M.S. Beevers Received: 2 October 2008 / Accepted: 6 January 2009 / Published online: 10 March 2009 © Springer Science+Business Media, LLC 2009 Abstract Experimental data from dielectric investigations of solutions of flourobenzene (FB) and its mesogenic derivative (1-fluoro-4-(4-pentylcyclohexyl) benzene (FPCHB) in 1,4-dioxane are reported for various mole fractions and temperatures. The molecular di- pole moments were determined using the Guggenheim-Debye method in the temperature range of 298.2 to 318.2 K. Both fluorinated compounds show a positive and small tem- perature coefficient for the effective dipole moment. Variations of the effective dipole mo- ment and correlation factor, g, with mole fraction in these mixtures were investigated using the Kirkwood-Frohlich equation. Dielectric measurements were also carried out on binary mixtures of FPCHB with 1-butanol for various concentrations at 318.2 K. The Kirkwood correlation factor, the Bruggeman factor, and the excess permittivity were determined. Keywords Fluorinated compounds · Permittivity · Dipole moment · Molecular association · Kirkwood factor · Polar binary mixtures 1 Introduction Measurement of the dielectric constant (relative permittivity) is a useful technique for char- acterizing molecular structure, solute-solute and solvent-solute interactions, and molecular ordering in solutions. The value of the dielectric constant is strongly related to molecular structure and intermolecular interactions [1–3]. Valuable information about the nature and strength of molecular interactions in liquid solutions, over a range of mole fractions or tem- peratures, can be obtained using dielectric studies. A large number of dielectric measurements have been carried out on polar solutions with various molecular structures and different functional groups, in order to understand and A. Ghanadzadeh Gilani ( ) · A. Ranjkesh Department of Chemistry, Faculty of Science, University of Guilan, Rasht, Iran e-mail: aggilani@guilan.ac.ir M.S. Beevers Department of Chemical Engineering and Applied Chemistry, Aston University, Birmingham B4 7ET, UK