Thermodynamics of Ion Association of s-Acetylthiocholine Halides and Perchlorate in Acetonitrile

Abstract

Thermodynamic parameters (∆Hº, ∆Gº, ∆Sº) and the activation energy (∆Es) were calculated to explain the limiting equivalent conductance (Λ0) and ion association constant (KA) of s-acetylthiocholine halides and perchlorate in acetonitrile at different temperatures by using conductance measurements. It has been evaluated by using Fuoss-Onsager equation. It is evident that the values of (Λ0) increase regularly with increase in temperature. For all salts of s-acetylthiocholine, (Λ0) indicates less solvation or higher mobility of the ions in all solvent systems studied. The free energy change ∆Gº values are negative for all salts (Br -, Iand ClO4 -). Clearly strengthening to interionic association at higher temperatures is largely caused by a decrease in the permitivity of the solvent. The positive values of (∆Hº) for three salts (Br -, Iand ClO4 -) show that the association processes are endothermic in nature. Entropy change (∆Sº) values are positive for all salts indicate the randomness of ions in all solvent systems studied.

Electrical Conductivity of S-Acetylthiocholine Halides and Perchlorate in Ethanol at 40 ºC

“…El-Hammamy et al [2][3][4][5][6]8 , measured the conductances of Sacetylthiocholine halides and perchlorate in methanol, ethanol, n-prpanol, n-butanol, 2-propanol and acetonitrile solutions at 25 ºC. They found that the same trends of solvation (aº) for all organic solvents are in agreement with the present results.…”

“…The solvation (aº) in Table-4 increases with increased the temperature from (35-40 ºC) for salts of S-acetylthiocholine Brto ClO4 -. The same results were obtained for these salts in ethanol 13 and acetonitrile at different temperatures from (30-35 ºC) 14 .…”

“…In continuation of our conductometric studies on Sacetylthiocholine salts in simple solvents [1][2][3][4][5] , the present work aims at determing the conductance values of the solution of S-acetylthiocholine halides and perchlorate in pure ethanol at 40 ºC to throw light on the behaviour of these salts in simple solvents and to examine the validity of Fuoss-Onsager equation for 1:1 associated electrolytes 6 .…”

Zwanzig Theory Application for Bromide and Iodide Ions in Pure Solvents at 25°C

“…They expound the scattering of the points and difference between the (ri intercept) and (ri slope) values to certain specific parameters such as solvation which are neglected in the continuum model and these show a very important role in determining mobility of ions. El-Hammamy et al [8], calculated the hydrated radii and hydrodynamic radii for acetylcholine ion and ClO and s-alkylisothiouronuim ions (s-Meis + , s-n-Buis + , sn-Amis + and s-n-Heptis + ) in water, methanol, n-propanol and CH3CN at 25°C. They found that the radii obtained from the slope increase with increase in size for both cation and anions.…”

Catalytic and Viscometric Behavior of HClO4-H2O System

“…On the basis of this approach, the structure modification of the water takes place by the addition of an acid. Such an influence has been investigated by conductance measurements for S-acetylthiocholine halides and perchlorates in methanol solution 9 . Many investigations have been carried out in aqueous solution catalyzed by both acid and base [10][11][12] (1) The mechanisms of many acid and base-catalyzed reactions have been established using kinetic data in order to measure the reaction rate in a wide range of acid or base concentrations 13 .…”