Viscosity Behavior of 18-Crown-6 in Aqueous and Carbon Tetrachloride Solutions at Different Temperatures and at Ambient Pressure

Abstract

The relative viscosity (ηr) and the viscosity B-coefficients in the equation ηr = 1 + Bc + Dc 2 , with c = concentration of 18-crown-6 (18C6) in aqueous and carbon tetrachloride solutions (0.02 to 0.3 mol L-1), have been determined in the temperature range (293.15 to 308.15) K and at ambient pressure. The values of the B- and D-coefficients are found to be high compared to those obtained for simple nonelectrolyte solutions. These values are further found to decrease and increase, respectively, as a function of temperature in aqueous solutions, while the value of the B-coefficient remains more or less constant in the case of CCl4 solutions in the studied temperature range.

Compressibility studies of aqueous and CCl4 solutions of 18-crown-6 at T=298.15K

“…The density data were obtained with 1 K or 2 K or 5 K intervals in temperature range of T = 293.15 K to T = 313.15 K. The density data of aqueous 18C6 solutions at T = 298.15 K were reported [3] already; however, we now report the same but at different temperatures. The density data for (18C6 + CCl 4 ) solutions at 5 K interval in temperature range T = 293.15 K to T = 308.15 K have been published earlier by us [17] and used here to supplement the sound velocity data. Sound velocities (u) were measured at T = 298.15 ± 0.05 K operating at a fixed frequency of 2 MHz.…”

Viscosity of Urea in the Mixture of N,N-Dimethylformamide and Water

“…It has been shown that the positive values of d B /d T testify to the solvent structure-destroying tendency of solute, while d B /d T < 0 shows the solvent structure-making tendency of solute . Such a behavior is observed in the case of neutral nonelectrolytes such as 18-crown-6 or amines …”

“…44 It has been shown that the positive values of dB/dT testify to the solvent structure-destroying tendency of solute, while dB/dT < 0 shows the solvent structure-making tendency of solute. 45 Such a behavior is observed in the case of neutral nonelectrolytes such as 18-crown-6 46 or amines. 47 Table 5 contains the values of dB/dT calculated for urea in the DMF + H 2 O mixture within the whole range of mixed solvent composition at temperature ranging from (293.15 to 308.15) K. As is seen in Figure 3, one can distinguish two characteristic areas, in which dB/dT of urea in the mixture shows values with opposite signs.…”

The Water–18-Crown-6 System: Experimental Investigation and Thermodynamic Modeling

“…10 Later the osmotic coefficients and densities of aqueous solutions of 18-crown-6 in the concentration range from (0.1 to 2.0) m at 298.15 K were published. 11 The relative viscosity of aqueous solutions [(0.02 to 0.3) mol•L −1 ] containing 18-crown-6 has been determined in the temperature range from (293.15 to 308.15) K by Dagade et al 13 All published data may be used for the parametrization of liquid phase model to obtain a self-consistent set of thermodynamic properties. Unfortunately, any information about standard thermodynamic functions of 18-crown-6 hydrates is absent.…”

“…The 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6) molecule is the most extensively characterized compound because it is the prototype synthetic macrocyclic polyether and a prominent compound in supramolecular chemistry. As well-known, hydration is a key process in the stability increase of 18-crown-6 complexes, which is why such a considerable number of studies have been devoted to the water–18-crown-6 system. − …”