- Conductivity and dissociation constants of quaternary ammonium perchlorates and picrates in 4-methyl-pentan-2-one
-
The dissociation of 14 ionophores, namely, seven symmetrical (C1 to C7) and five asymmetrical quaternary ammonium perchlorates and two tetraalkylammonium picrates (all with linear hydrocarbon chains), in 4-methyl-pentan-2-one was studied at 25 °C (εr = 12.92) using the conductance method. The values of the association constants of the quaternary ammonium cation, Ct+, with ClO4- vary from (7.4 ± 0.3) ·103 L·mol-1 for tetramethylammonium to (2.4 ± 0.1) ·103 L·mol-1 for tetrahexyl- and tetraheptylammonium; a distinct dependence on the size of the Ct+, especially for symmetrical cations, is evident. The values of the limiting molar conductivities Λ0/S·mol-1·cm2 vary from 122.8 to 90.0 (± 0.7). The plot of Λ0 versus the reciprocal cube root of the total van der Waals volume of the cations, V Ct-1/3, is close to linear up to tetrapentylammonium and hexadecyltrimethylammonium, while for larger cations (with 21 to 28 carbon atoms) the Λ0 values stay practically constant. At the same time, symmetrical and asymmetrical cations with the same VCt values possess equal mobility.
- Goga, Sergey T.,Lebed, Alexander V.,McHedlov-Petrossyan, Nikolay O.
-
body text
p. 1887 - 1892
(2011/07/30)
-
- SURFACE BEHAVIOUR OF TETRAPROPYLAMMONIUM CATION AT THE MERCURY/SOLUTION INTERFACE MEASURED BY USE OF CONTROLLED CONVECTIVE ADSORPTIVE ACCUMULATION
-
Using drop time technique with long drop times and a controlled convection of the solution the surface tension data of Hg with tetrapropylammonium perchlorate in 0.1 mol l-1 NaClO4 in the concentration range 4*10-6-3*10-3 mol l-1 have been obtained.The corresponding adsorption parameters have evaluated from the Frumkin isotherm both at constant potential E and at constant charge q.Both E and q could be chosen as an independent electrical variable.The maximum free adsorption energy amounts to approx. -36.5 kJ mol-1.The congruence of adsorption isotherms with respec t to E and with respect to q was very well fulfilled for the surface coverage Τ 0.6-0.7.
- Novotny, Ladislav,Smoler, Ivan
-
p. 2525 - 2534
(2007/10/02)
-