scholarly journals Solvent Effect on Ion-pair Extraction of 2-(2-Pyridylazo)-1-naphthol-4-sulfonate Anion with Solvated Hydroxonium Ion Using Alcohols and 1-Octanol/Octane Mixed Solvents.

2001 ◽  
Vol 17 (2) ◽  
pp. 291-295 ◽  
Author(s):  
Tetsuyoshi NAITO ◽  
Yugo TSUIKI ◽  
Hiromichi YAMADA
2011 ◽  
Vol 324 ◽  
pp. 166-169 ◽  
Author(s):  
Farah Zeitouni ◽  
Gehan El-Subruiti ◽  
Ghassan Younes ◽  
Mohammad Amira

The rate of aquation of bromopentaammine cobalt(III) ion in the presence of different types of dicarboxylate solutions containing tert-butanol (40% V/V) have been measured spectrophotometrically at different temperatures (30-600°C) in the light of the effects of ion-pairing on reaction rates and mechanism. The thermodynamic and extrathermodynamic parameters of activation have been calculated and discussed in terms of solvent effect on the ion-pair aquation reaction. The free energy of activation ∆Gip* is more or less linearly varied among the studied dicarboxylate ion-pairing ligands indicating the presence of compensation effect between ∆Hip* and ∆Sip*. Comparing the kip values with respect of different buffers at 40% of ter-butanol is introduced.


1995 ◽  
Vol 73 (12) ◽  
pp. 2131-2136 ◽  
Author(s):  
Yixing Zhao ◽  
Gordon R. Freeman

The electrical conductance of LiNO3 in tert-butanol–water mixed solvents changes gradually from "normal" in pure water to "abnormal" in pure tert-butanol. In water the measured specific conductance increases with increase of temperature, and in tert-butanol the conductance decreases with increase of temperature. In pure tert-butanol, the electrical conductances of NH4ClO4 and LiClO4 increase with the salt concentration and temperature at lower temperatures, but decrease at higher temperatures. The molar conductivity Λ0(10−4 S m2 mol−1) in tert-butanol at 300 K is 5.0 for NH4ClO4 and 4.0 for LiClO4. Both activation energies EΛ0 are 17 kJ mol−1, which gives an unusual correlation between Λ0 and viscosity η(mPa s): [Formula: see text] The values of Λ0 for NH4NO3 and LiNO3 in tert-butanol could not be measured, because ion aggregation is significant even at the lowest concentrations required to obtain conductances sufficiently above that of the solvent. The measured temperature coefficient of LiNO3 conductance in tert-butanol is negative. Ion clustering of nitrate salts is attributed to poor solvation of the planar NO3− ions by the globular tert-butanol molecules. Ion aggregation in tert-butanol increases with increasing T, due to the relatively rapid decrease of the value of εT. Corrections are listed for reaction kinetics parameters for nitrate salts in pure tert-butanol solvent reported in Can. J. Chem. 73, 392 (1995). Keywords: tert-butanol, ion-pair aggregation, lithium nitrate, electrical conductance, solvent effects.


1984 ◽  
Vol 62 (11) ◽  
pp. 2245-2248
Author(s):  
Amrita Lal De ◽  
Tapas Kumar De

Thermodynamic dissociation constants (sK) of p-nitroanilinium ion (BH+) have been determined at 25 °C in aqueous mixtures of 10, 30, 50, 70, and 90 wt.% of glycerol (GL) by spectrophotometric measurements. Standard free energies, [Formula: see text], of p-nitroaniline (B) from water to mixed solvents have been evaluated from the measurement of solubilities at 25 °C. p(sK) values decrease with increase in mol% of GL and pass through a minimum and then increase very slowly. The solvent effect on the dissociation, δ(ΔG0) = 2.303RT [p(sK)N – p(wK)N] has been discussed in terms of the standard free energies of transfer [Formula: see text] from water to aqueous mixtures of GL of the uncharged base (B), the hydrochloride of the base (BHCl), hydrochloric acid (HCl), and also in terms of the individual species involved in the dissociation process. The solvent effect in trihydric alcohol – water (GL + H2O) system has been compared with those in dihydric alcohol – water (ethylene glycol + water) and monohydric alcohol – water (ethanol + water) systems available from literature. The much less solvent effect in GL + H2O has been primarily attributed to the contrasting nature of interaction of H+ and of partially charged H atoms of—NH3+ group in BH+ compared to those in other two solvent systems.


2006 ◽  
Vol 38 (1) ◽  
pp. 5-9 ◽  
Author(s):  
Xing-Mei Lu ◽  
Wei-Guo Xu ◽  
Xiao-Hong Chang ◽  
Dian-Zhen Lu ◽  
Jia-Zhen Yang
Keyword(s):  

1950 ◽  
Vol 28b (4) ◽  
pp. 140-155 ◽  
Author(s):  
C. A. Winkler ◽  
J. Halpern ◽  
G. W. Brady

Relations for the solvent effect on the rate of a unimolecular, nonionic reaction are derived, using existing theories of solutions and of chemical kinetics. The kinetics of the cis-trans isomerization of azobenzene were investigated in 16 pure solvents. A linear relation between the activation energy, E, and the square root of the internal pressure of the solvent, (P′S)1/2 was found, in agreement with the theory. Linear relations between log A and E, and between log k and (P′S)1/2 were also found, but the results for the reaction in highly polar solvents deviated significantly from these relations. The kinetics of the reaction in mixed solvents indicate that the azobenzene is preferentially surrounded by the component in which it is more readily soluble.


2002 ◽  
Vol 51 (9) ◽  
pp. 751-758 ◽  
Author(s):  
Masakazu HASEGAWA ◽  
Noriaki FURUKAWA ◽  
Tetsuyoshi NAITO ◽  
Hiromichi YAMADA

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