Liquid junction potentials across the interface between the aqueous saturated calomel electrode and some nonaqueous solvents, based on the tatb assumption

1983 ◽  
Vol 36 (9) ◽  
pp. 1779 ◽  
Author(s):  
J Datta ◽  
S Bhattacharya ◽  
KK Kundu
Keyword(s):  
Saturated Calomel Electrode ◽  
Nonaqueous Solvents ◽  
Aprotic Solvents ◽  
Nonaqueous Solvent ◽  
Liquid Junction ◽  
Solvent Interactions ◽  
Electrode Potentials ◽  
Protic Solvents ◽  
Liquid Junction Potentials ◽  
Dipolar Aprotic Solvents

The liquid junction potentials (Ej) across aqueous saturated KCl/nonaqueous solvent junctions have been determined within the framework of the tetraphenylarsonium tetraphenylborate (tatb) extra- thermodynamic assumption. The nonaqueous solvents comprise methanol, ethylene glycol, acetonitrile, propylene carbonate, dimethylformamide and dimethyl sulfoxide. The Ej values obtained are fairly small (below 40 mV) in the case of protic solvents and fairly large (within 100-200 mV) in the case of dipolar aprotic solvents, as expected if primarily guided by solvent-solvent interactions across the liquid junctions. The results allow the aqueous saturated calomel electrode to be used to relate electrode potentials in different solvents.

Ion–solvent interactions of some ions in dipolar aprotic solvents at 25 °C

1990 ◽  
Vol 86 (3) ◽  
pp. 489-494
Author(s):  
Natalija Schmelzer ◽  
Jürgen Einfeldt ◽  
Manfred Grigo
Keyword(s):  
Aprotic Solvents ◽  
Solvent Interactions ◽  
Dipolar Aprotic Solvents

scholarly journals A Simple and Efficient Protocol for Proline-Catalysed Asymmetric Aldol Reaction

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 649
Author(s):  
Marco Giuseppe Emma ◽  
Alice Tamburrini ◽  
Ada Martinelli ◽  
Marco Lombardo ◽  
Arianna Quintavalla ◽  
...  
Keyword(s):  
Aldol Reaction ◽  
Aprotic Solvents ◽  
Asymmetric Aldol ◽  
Protic Solvents ◽  
Asymmetric Aldol Reaction ◽  
Reaction Media ◽  
Dipolar Aprotic Solvents ◽  
Effective Reaction

The proline-catalysed asymmetric aldol reaction is usually carried out in highly dipolar aprotic solvents (dimethylsulfoxide, dimethylformamide, acetonitrile) where proline presents an acceptable solubility. Protic solvents are generally characterized by poor stereocontrol (e.g., methanol) or poor reactivity (e.g., water). Here, we report that water/methanol mixtures are exceptionally simple and effective reaction media for the intermolecular organocatalytic aldol reaction using the simple proline as the catalyst.

Estimation of transfer activity coefficients for single ions between dipolar aprotic solvents from the E.M.F. of cells with liquid junction

1983 ◽  
Vol 36 (9) ◽  
pp. 1767 ◽  
Author(s):  
SS Goldberg ◽  
O Popovych
Keyword(s):  
Activity Coefficients ◽  
Salt Bridge ◽  
Aprotic Solvents ◽  
Liquid Junction ◽  
Transfer Activity ◽  
Novel Method ◽  
Glass Electrodes ◽  
Tetraethylammonium Perchlorate ◽  
Dipolar Aprotic Solvents ◽  
Junction Potential

Transfer activity coefficients for the sodium ion, logmγNa, between pairs of dipolar aprotic solvents were estimated from the e.m.f. of cells consisting of two sodium-selective electrodes in different solvents connected by a salt-bridge of triisoamylbutylammonium tetraphenylborate [(tab+)BPh4-], or tetraethylammonium picrate (Et4NPic), or tetraethylammonium perchlorate (Et4NclO4). The solvents were: acetonitrile (MeCN), N,N-dimethylformamide (HCONMe2), dimethyl sulfoxide (Me2SO), propylene carbonate (pcar), and N-methylformamide (HCONHMe). Values of logmγNA were estimated first by neglecting the liquid-junction potential E, and then, for some systems, by applying an Ej correction from theory. A novel method of estimating transfer activity coefficients for single ions, based on the Ej equation, was demonstrated on the (tab+) and Pic-ions. Transfer activity coefficients for the hydrogen ion between MeCN and HCONMe2 as well as MeCN and Me2SO were similarly estimated from the e.m.f. of two pH (glass) electrodes immersed in buffer media in the above pairs of solvents.

A New Method for the Estimation of Transfer Activity Coefficients of Ions From the E.M.F. of Cells With Liquid Junction

1988 ◽  
Vol 41 (10) ◽  
pp. 1523 ◽  
Author(s):  
A Berne ◽  
O Popovych
Keyword(s):  
Concentration Dependence ◽  
Activity Coefficients ◽  
Salt Bridge ◽  
Liquid Junction ◽  
Transfer Activity ◽  
Liquid Junction Potentials ◽  
Solvent Component ◽  
Calculated Liquid ◽  
Dipolar Aprotic Solvents ◽  
Junction Potential

Transfer activity coefficients of the tetraalkylammonium ions, logmγR, where R+ = Me4N+, Et4N+, Pr4N+ and Bu4N+, and of the picrate ion, logmγPic, between pairs of dipolar aprotic solvents, S1 → S2, were evaluated by combining the e.m.f . of cells Ag(cryst.)|AgClO4|RX|AgClO4|Ag( cryst .)�������������������������������� S1 ������ S2with the calculated liquid-junction potentials, Ej. The salt-bridge electrolyte RX was RClO4 and R Pic for the determinations of logmγR and logmγPic, respectively, and the solvents were: acetonitrile ( MeCN ), N,N- dimethylformamide (HCONMe2), dimethyl sulfoxide (Me2SO) and propylene carbonate ( pcar ). The logmγR values showed a systematic variation with the AgClO4 concentration, apparently caused by the concentration dependence of the solvent component of the liquid-junction potential, Ej,s, neglected in the calculations. However, the above concentration dependence was virtually eliminated from the values of logmγPic when they were calculated with the aid of our concentration-dependent logmγR data. For a number of our cells it was possible to evaluate the Ej,s, with the aid of literature data. The solvent component of Ej was found to be appreciable and varied both with the AgClO4 and the RX concentration. The Ej,s, was particularly large for cells containing pcar , with a maximum of -172 mV for the pcar | MeCN junction.

Solvation of ions. XXV. Partial molal volumes of single ions in protic and dipolar aprotic solvents

1975 ◽  
Vol 28 (5) ◽  
pp. 955 ◽  
Author(s):  
MRJ Dack ◽  
KJ Bird ◽  
AJ Parker
Keyword(s):  
Propylene Carbonate ◽  
Dimethyl Sulphoxide ◽  
Aprotic Solvents ◽  
Solvent Interactions ◽  
Partial Molal Volumes ◽  
Steric Crowding ◽  
Solvation Of Ions ◽  
Molal Volumes ◽  
Solvent Molecules ◽  
Dipolar Aprotic Solvents

Partial molal volumes at 25� are reported for some 1 : 1 electrolytes, and for triphenylmethane, in dimethyl sulphoxide, N,N- dimethylformamide, acetonitrile, propylene carbonate, formamide and hexamethylphosphoramide. The assumption that ΔV�tr(Ph4As+) = ΔV�tr(BPh4-) was used to obtain ionic partial molal volumes of transfer from water to the non-aqueous solvents. Solvent compressibility appears to determine the partial molal volumes of non-electrolytes and large hydrophobic ions in solution. Values of ΔV�tr for cations and anions are discussed in terms of ion-solvent interactions, solvent-solvent interactions and steric crowding of large solvent molecules around the ions.

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