Dielectric relaxation and intermolecular association for 1-decanol. Temperature and dilution dependences of monomer and three hydrogen-bonded species.

The dielectric constants and losses have been measured at frequencies from 1.35 to 4500 MHz for pure 1-decanol at 15–40 °C and for cyclohexane and heptane solutions of 1-decanol at 25°C. The absorption has been resolved into three different Debye-like dispersion regions. The assignments of the three regions were made as follows: the first region being due to a linear hydrogen-bonded chain polymer (C1), the second one to a chain dimer and trimer (C2), and the third one to a free monomer (C3). Four concentrations of these species (C1−3) and a nonpolar cyclic polymer (CR) were evaluated by applying a modified Kirkwood–Fröhlich equation to each dispersion region. Each of the four concentrations indicates a reasonable behavior regarding the temperature and dilution dependences. The C1 decreases and, mainly, the C3 increases as the temperature increases. For cyclohexane and heptane solutions, the C1 decreases rapidly and the CR increases correspondingly with decreasing alcohol concentration. The free energies of activation are 23.2 for the first region, 17.3 for the second region, and 11.9 kJ mol−1 for the third region.