Studies of partial molar volumes of 18-crown-6 in water at 25 C

Thermodynamics of complexation of aqueous 18-crown-6 with potassium ion: apparent molar volumes and apparent molar heat capacities of aqueous 18-crown-6 and of the (18-crown-6+potassium chloride) complex at temperatures (278.15 to 393.15) K, at molalities (0.02 to 0.3) mol·kg−1, and at the pressure 0.35 MPa

“…Our V / results for 18C6(aq) agree well with literature values [24][25][26][27][28][29][30][31][32][33]. We give in table 5 our calculated V 2 ¼ ð223:16 AE 0:3Þ cm 3 Á mol À1 (= V / at m* = 0) at T* = 298.15 along with V 2 from the literature [24,[26][27][28][29][30][31][32][33]. The average of the literature values is (223.4 ± 0.8) cm 3 AE mol À1 , which differs from our value by 0.2 cm 3 AE mol À1 .…”

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

“…This is as expected since non-aqueous solvents are more compressible than water due to structural differences. Earlier we reported [2] that apparent molar volume (/ V ) of solute goes through a minimum (figure 2) at about 0.04 x 2 and such a behaviour is similar to aqueous solutions of alcohols, amines, ethers etc. [26][27][28][29] which is due to hydrophobic hydration.…”

“…Recent work from our laboratory has been concerned with the interpretation of measured near infra-red (NIR) spectral and thermodynamic properties like activity coefficients and volumes in binary aqueous and CCl 4 solutions involving 18-crown-6 (1, 4, 7, 10, 13, 16 hexaoxacyclooctadecane) as a solute [1][2][3]. The 18-crown-6 (18C6) is an archetype of the family of macrocyclic polyether compounds known as crown-ethers and represent a treatable model compound [4,5].…”

Interfacial tension studies of crown ethers at air/water and hexane/water interfaces

“…Comparison of area values show that 18-crown-6 has higher area than dicyclohexano-18-crown-6 at both air/water and hexane/water interfaces. The partial molar volume of 18-crown-6 in the aqueous phase is about 220 cm 3 /mol [25] and that of dicyclohexano-18-crown-6 which was calculated from the densities of its aqueous solution is about 320 cm 3 /mol. However, the occupied molecular area of dicyclohexano-18-crown-6 at interface is less than that of 18-crown-6.…”