Volumetric properties and compressibilities of alkyltrimethylammonium bromides and sodium alkylsulphates in aqueous solution

Abstract

Density and sound velocity data for aqueous solutions at 298.2 K containing alkyltrimethylammonium bromides and sodium alkylsulphates were analysed to yield partial molar volumes and isentropic compressions. The calculated contributions of methylene groups to the properties of alkyltrimethylammonium cations and alkylsulphate anions show no dependence on position in the alkyl chains and a common contribution to the ionic partial molar volumes over the range methyl ≤ n‐octyl for the sulphates and n‐propyl ≤ n‐hexyl for the alkyltrimethylammonium ions. However, a switch in head group from trimethylammonium to sulphate changes the contribution of methylene groups to estimated partial molar isentropic compressibilities. The reasons for this sensitivity are discussed in terms of hydration characteristics. © 1998 John Wiley & Sons, Ltd.

Volumetric Properties of Alkyltrimethylammonium Bromides in Aqueous Solutions

“…In case of higher carbon-numbered surfactants (i.e., C 10 TAB, C 12 TAB, C 14 TAB, and C 16 TAB), we find that the limiting slopes of (ϕ V − A V c 1/2 ), that is, B V are positive meaning that hydrophobic interactions are predominant over the charged water dipole interaction even in very dilute concentration region. The variation of (ϕ V − 1.868c 12,17,23,26 and the ϕ V 0 values for C 12 TAB at 293.15 and 303.15 K are also in good agreement with the values reported by Zhang et al 22 The B V (deviation parameter) of eq 2 is a measure of the solute− solute/ion−ion interactions that are collected in Table 4. In general, for kosmotropic effect (structure making ions) B V is negative while for chaotropic effect (structure breaking ions) it is positive.…”

“…The alkyltrimethylammonium salts offer an opportunity to study their properties in very dilute solutions as well the property dependence on the number of hydrophobic groups form relatively simple patterns with constant increments per additional methylene group. Buwalda et al 17 have discussed that −NMe 3 + head groups have a profound influence on the hydration of linked hydrophobic alkyl groups. Considering all these points, we planned to generate systematic data for densities for aqueous solutions of quaternary salts such as hexyl-, octyl-, decyl-, dodecyl-, tetradecyl-, and hexadecyl-trimethylammonium bromides at 293.15, 298.15, and 303.15 K. The data have been used to calculate apparent molar volumes for all the systems at all the studied temperatures.…”

Molar Partial Compressibilities and Volumes, 1H NMR, and Molecular Modeling Studies of the Ternary Systems β-Cyclodextrin + Sodium Octanoate/Sodium Decanoate + Water

“…From our NaO and NaD data (Table ), the compressibility per CH 2 group would be −0.2 PPa -1 m 3 mol -1 , smaller in absolute value than that of Vikingstad. Kudryashov et al in a recent paper obtain for a homologue series of alkyltrimethylammonium bromides ( n = 8 to n = 16) −0.87 PPa -1 m 3 mol -1 , and Buwalda et al . obtain −0.54 PPa -1 m 3 mol -1 for the shorter homologues of the same series ( n = 3−6).…”

Isentropic Compressibility of Aqueous and Methanolic Sodium Thiocyanate Solutions

“…It may be presumed that the vibrational compressibility predominantly contributes to the isentropic compressibility within the concentration and temperature range of this study. Onori (1988) derived the following relation between the conventional apparent molal isentropic compressibility, K s,φ (Blandamer, 1998;Buwalda et al, 1998) and the product of the isentropic compressibility, K s,1 , and the molar volume, V 1 , of the solvent to estimate the total hydration Journal of Chemical and Engineering Data, Vol. 44, No.…”