Thermodynamics of transfer of tetrabutylammonium bromide from water to aqueous urea solutions and the effects on the water structure

1972 ◽  
Vol 76 (9) ◽  
pp. 1366-1369 ◽  
Author(s):  
T. S. Sarma ◽  
J. C. Ahluwalia
Keyword(s):  
Tetrabutylammonium Bromide ◽  
Water Structure ◽  
Thermodynamics Of Transfer ◽  
Aqueous Urea

Transfer thermodynamics of p-nitroaniline in aqueous solutions of some ionic and non-ionic cosolvents and the structuredness of the solvents

1983 ◽  
Vol 61 (3) ◽  
pp. 625-631 ◽  
Author(s):  
Jayati Datta ◽  
Kiron K. Kundu
Keyword(s):  
Three Dimensional ◽  
Water Structure ◽  
Scaled Particle Theory ◽  
Aqueous Mixtures ◽  
Promoting Effect ◽  
Salting Out ◽  
Aqueous Urea ◽  
Different Temperatures ◽  
Composition Profiles ◽  
Transfer Thermodynamics

Standard free energies [Formula: see text] and entropies [Formula: see text] of transfer of p-nitroaniline (pNA) from water to aqueous mixtures of some ionic and non-ionic cosolvents like KBr, urea (U), propylene glycol (PG), glycerol (GL), dioxane (D), and 1,2-dimethoxyethane (DME) have been determined from solubility measurements at different temperatures. The observed [Formula: see text]–composition profile in KBr solution appears to result from the well known salting-out effect of the salt and those in aqueous poly-ols and ethers are the result of the combined effects of dispersion and "acid–base" type interactions but that in aqueous urea solutions is governed by the "salting-out" type interaction by the predominant zwitterionic form of urea. The observed [Formula: see text]–composition profiles as well as those obtained after correcting for the "cavity-effect", as estimated tentatively by the scaled particle theory (SPT), were examined in the light of Kundu et al.'s semi-quantitative theory proposed earlier. The latter profiles suggest that unlike isopropyl alcohol (IPA), the poly-ols and ethers as well as KBr and urea induce structure breaking of three dimensional (3D) water structure right from the initial compositions. Moreover, the observed "roller-coaster" type behaviour of the profile in aqueous urea is indicative of the effect of urea–water aggregation around 4–10 m urea. Also, the observed graded reduction of structure-promoting effect of IPA in PG and GL cosolvent systems confirms that structuring and destructuring ability of a cosolvent depends on the ratio of hydrophobicity to hydrophilicity of the cosolvent.

Modeling of transfer properties using revised HKF theory: thermodynamics of transfer of an amino acid and small peptides from water to urea–water solutions at 298.15 K

1997 ◽  
Vol 75 (4) ◽  
pp. 456-464 ◽  
Author(s):  
Andrew W. Hakin ◽  
Lori L. Groft ◽  
Jocelyn L. Marty ◽  
Matthew L. Rushfeldt
Keyword(s):  
Heat Capacities ◽  
Semiempirical Calculation ◽  
Standard State ◽  
Small Peptides ◽  
Apparent Molar Heat Capacities ◽  
Thermodynamics Of Transfer ◽  
Aqueous Urea ◽  
Transfer Thermodynamics ◽  
Transfer Properties ◽  
Calculation Procedures

Relative densities, [Formula: see text] and heat capacity ratios, [Formula: see text] have been measured for aqueous solutions of glycine, glycylglycine, and glycylglycylglycine in aqueous urea solutions containing 1–13 mol kg−1 urea. These data have been used to calculate apparent molar volumes, [Formula: see text] and apparent molar heat capacities, [Formula: see text] which in turn have been used to obtain standard state volumes, [Formula: see text] and standard state heat capacities, [Formula: see text].Volumes and heat capacities of transfer from water to urea have been calculated from our reported standard state data. Heat capacities of transfer of the investigated systems have been modeled using a procedure developed from the semiempirical calculation procedures proposed by Helgeson, Kirkham, and Flowers. Keywords: amino acids, peptides, calorimetry, transfer thermodynamics, HKF theory.

Currents and water structure north of the Vema Channel

2018 ◽  
Vol 18 (5) ◽  
pp. 1-6 ◽  
Author(s):  
E. G. Morozov ◽  
R. Yu. Tarakanov ◽  
D. I. Frey ◽  
D. G. Borisov
Keyword(s):  
Water Structure

Use of Nafion membranes in laboratory organic electrosynthesis

1988 ◽  
Vol 53 (12) ◽  
pp. 3164-3170 ◽  
Author(s):  
Jaromír Hlavatý ◽  
Jiří Volke
Keyword(s):  
Glassy Carbon ◽  
Quaternary Ammonium ◽  
Tetrabutylammonium Bromide ◽  
Nafion Membrane ◽  
Carbon Anode ◽  
Tetrabutylammonium Hydroxide ◽  
Nafion Membranes ◽  
Divided Cell ◽  
A Cell ◽  
Tetrabutylammonium Iodide

Electrolysis of quaternary ammonium bromides and iodides in a divided cell with a Nafion membrane yields quaternary polyhalogenides at a carbon anode in water-ethanolic anolytes. The electrodialysis of tetrabutylammonium iodide in a cell with a Nafion membrane enables generation of tetrabutylammonium hydroxide. In electrolytic reduction of nitrobenzene in presence of 1,3-dibromopropane, N-phenylisooxazolidine results in an approx. 60% yield. This electrosynthesis takes place in dimethylformamide with tetrabutylammonium bromide at a glassy-carbon cathode in a divided cell. In the electroreduction of lobelanine hydrogensulfate in a divided cell in acid water-ethanolic media at a lead cathode prevalently lobelanidine has been obtained.

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