THE ELECTRICAL CONDUCTIVITIES OF SOME TETRA-n-ALKYLAMMONIUM SALTS IN ACETONITRILE

1965 ◽  
Vol 43 (5) ◽  
pp. 1215-1221 ◽  
Author(s):  
A. C. Harkness ◽  
H. M. Daggett Jr.
Keyword(s):  
Dissociation Constants ◽  
Relative Order ◽  
Electrical Conductivities ◽  
Ionic Conductances ◽  
Order Of Magnitude ◽  
Alkylammonium Salts ◽  
Ion Size ◽  
Limiting Equivalent Conductances

The conductances of a number of tetra-n-alkylammonium bromides and iodides have been measured in acetonitrile. Limiting equivalent conductances and dissociation constants have been evaluated by two methods. Limiting equivalent ionic conductances have been evaluated from these results. Correlations have been made of the effect of ion size on the ionic conductances and on the relative order of magnitude of the dissociation constants. In an appendix the limiting ionic conductances of a number of other ions have been collected from the existing literature.

scholarly journals ELECTROMETRIC DETERMINATIONS OF THE DISSOCIATION OF GLYCOCOLL AND SIMPLE PEPTIDES1

1930 ◽  
Vol 14 (2) ◽  
pp. 255-275 ◽  
Author(s):  
Philip H. Mitchell ◽  
Jesse P. Greenstein
Keyword(s):  
Ionic Strength ◽  
Dissociation Constants ◽  
Hydrogen Ion ◽  
Carboxyl Groups ◽  
Relative Order ◽  
Specific Ion Effects ◽  
Ion Activity ◽  
Order Of Magnitude ◽  
Ion Effects ◽  
Basic Dissociation

1. The apparent acid and basic dissociation constants were determined potentiometrically by the methods of hydrolysis and of titration for the following ampholytes: Glycocoll, glycylglycocoll, alanylglycocoll, valylglycocoll, leucylglycocoll, methylleucylglycocoll, phenylalanylglycocoll and glycylglycylglycocoll. The constants were also determined in the presence of KCl and of K2SO4 at equal ionic strength. 2. In general, the relative order of magnitude of the constants decreased as the number of carbon atoms between amino and carboxyl groups increased. An explanation of this is offered on the basis of theories of electronic structure. 3. The application of the modern concepts of solutions to the case of the ampholytic ions is discussed. The inadequacy of the present theories is pointed out. 4. The constants were found, in general, to be functions of the hydrogen ion activity and the ionic strength of the solutions. Apparent contradictions to the Debye-Hückel theory are pointed out and partially explained on the basis of specific ion effects.

Conductimetric studies of ionic association of tetraalkylammonium halides in iso-propanol + water mixtures at 25 °C. Part II.

1988 ◽  
Vol 66 (7) ◽  
pp. 1720-1727 ◽  
Author(s):  
Auaz Ahmad Ansari ◽  
M. R. Islam
Keyword(s):  
Dielectric Constant ◽  
Association Constant ◽  
Ionic Association ◽  
Size Parameter ◽  
Solvent Interactions ◽  
Tetraalkylammonium Ions ◽  
Conductance Data ◽  
Electrical Conductivities ◽  
Ion Size ◽  
Tetraalkylammonium Halides

Electrical conductivities of Me4NBr, Et4NBr, Pr4NBr, Bu4NBr, and Bu4PBr have been measured in isopropanol + water (2-PrOH + H2O) mixtures covering the approximate range of dielectric constant (71.40 ≥ D ≥ 19.40) at 25 °C. The conductance data have been analysed by using the Fuoss-1978 (F78) conductance equation and the results compared with those obtained from the Fuoss–Onsager–Skinner (FOS) equation. The values of the limiting equivalent conductance, Λ0, the association constant, KA, and the distance of ion-size parameter [Formula: see text] are computed from these data. A better fit of the conductance data was provided by the F78 equation. Ion–solvent interactions and effective sizes of tetraalkylammonium ions are also discussed in order to understand the magnitude of the ionic association. The overall association behaviour of these salts has been found to increase with decrease in dielectric constant of the medium.

Electrocatalytic conversion of CO2 to produce solar fuels in electrolyte or electrolyte-less configurations of PEC cells

2015 ◽  
Vol 183 ◽  
pp. 125-145 ◽  
Author(s):  
C. Ampelli ◽  
C. Genovese ◽  
B. C. Marepally ◽  
G. Papanikolaou ◽  
S. Perathoner ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Gas Diffusion ◽  
Solar Fuels ◽  
The Other ◽  
Phase Cell ◽  
Relative Order ◽  
Electrocatalytic Reduction ◽  
Pec Solar Cells ◽  
Order Of Magnitude ◽  
Pec Cells

The electrocatalytic reduction of CO2 is studied on a series of electrodes (based on Cu, Co, Fe and Pt metal nanoparticles deposited on carbon nanotubes or carbon black and then placed at the interface between a Nafion membrane and a gas-diffusion-layer electrode) on two types of cells: one operating in the presence of a liquid bulk electrolyte and the other in the absence of the electrolyte (electrolyte-less conditions). The results evidence how the latter conditions allow productivity of about one order of magnitude higher and how to change the type of products formed. Under electrolyte-less conditions, the formation of >C2 products such as acetone and isopropanol is observed, but not in liquid-phase cell operations on the same electrodes. The relative order of productivity in CO2 electrocatalytic reduction in the series of electrodes investigated is also different between the two types of cells. The implications of these results in terms of possible differences in the reaction mechanism are commented on, as well as in terms of the design of photoelectrocatalytic (PEC) solar cells.

Electrical conductivities of quaternary ammonium salts in acetone.: Part III. Ion-pair formation

1968 ◽  
Vol 46 (12) ◽  
pp. 2005-2011 ◽  
Author(s):  
W. A. Adams ◽  
K. J. Laidler
Keyword(s):  
Dissociation Constants ◽  
Ion Pairs ◽  
Ion Pair ◽  
Pair Formation ◽  
Quaternary Ammonium Salts ◽  
Acetone Solution ◽  
Ammonium Salts ◽  
Electrical Conductivities ◽  
Tetraethylammonium Iodide ◽  
Kbar Pressure

The ion-pair dissociation constants determined from a Shedlovsky analysis of conductivity (see Part I) were used to calculate the enthalpy, the internal energy at constant volume, the entropy, and the volume of dissociation of tetramethylammonium iodide, tetraethylammonium iodide, and tetra-n-propylammonium iodide ion pairs in acetone solution. The sign and magnitude of these parameters over the range of conditions investigated, temperature 25 to 55 °C and atmospheric to 1.1 kbar pressure, indicated that the free ions in acetone solution are extensively solvated and that, depending on the conditions, solvent-shared or solvent-separated ion pairs are formed.

scholarly journals ON GUAIACOL SOLUTIONS

1934 ◽  
Vol 17 (4) ◽  
pp. 549-561 ◽  
Author(s):  
Theodore Shedlovsky ◽  
Herbert H. Uhlig
Keyword(s):  
Electrical Conductivity ◽  
Dissociation Constants ◽  
Dielectric Constants ◽  
Conductivity Measurements ◽  
Ionic Equilibrium ◽  
Weak Electrolytes ◽  
Ionic Mobilities ◽  
Water Saturated ◽  
Limiting Equivalent Conductances ◽  
Sodium And Potassium

1. Measurements on the densities, viscosities, dielectric constants, and specific conductances of pure anhydrous and water-saturated guaiacol at 25°C. are reported. 2. The solubility of water in guaiacol at 25°C., and its effect on the electrical conductivity of a sodium guaiacolate solution is given. 3. Electrical conductivity measurements are reported on solutions of sodium and potassium guaiacolates in water-saturated guaiacol at 25°C. 4. The decrease of electrical conductivity with increasing concentration for these salts is explained on the basis of an ionic equilibrium combined with the interionic attraction theory of Debye and Hückel. 5. The limiting equivalent conductances of sodium and potassium guaiacolates in water-saturated guaiacol at 25°C., the corresponding limiting ionic mobilities, and the dissociation constants are computed from the conductivity measurements. The salts are found to be weak electrolytes with dissociation constants of the order of 5 x 10–6.

scholarly journals Function of the Fibronectin-Binding Serum Opacity Factor of Streptococcus pyogenes in Adherence to Epithelial Cells

2004 ◽  
Vol 72 (7) ◽  
pp. 4302-4308 ◽  
Author(s):  
Sonja Oehmcke ◽  
Andreas Podbielski ◽  
Bernd Kreikemeyer
Keyword(s):  
Epithelial Cells ◽  
Streptococcus Pyogenes ◽  
Binding Proteins ◽  
Dissociation Constants ◽  
Cell Adherence ◽  
Latex Beads ◽  
Serum Opacity Factor ◽  
Order Of Magnitude ◽  
Fibronectin Binding ◽  
Adherence Inhibition

ABSTRACT The serum opacity factor (SOF) of Streptococcus pyogenes is a serotyping tool and pathogenesis factor. Using SOF-coated latex beads in cell adherence assays and antiserum directed against SOF in S. pyogenes-HEp-2 cell adherence inhibition experiments, we demonstrate SOF involvement in the fibronectin-mediated adherence of S. pyogenes to epithelial cells. SOF exclusively targets the 30-kDa N-terminal region of fibronectin. The interaction revealed association and dissociation constants 1 order of magnitude lower than those of other S. pyogenes fibronectin-binding proteins.

Reactions of 1,3-diacylthioureas with methoxide ion and with amines

1987 ◽  
Vol 52 (1) ◽  
pp. 120-131 ◽  
Author(s):  
Jaromír Kaválek ◽  
Josef Jirman ◽  
Vojeslav Štěrba
Keyword(s):  
Carbonyl Group ◽  
Rate Constants ◽  
Dissociation Constants ◽  
Equilibrium Constants ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Order Of Magnitude ◽  
Acetyl Group ◽  
Methoxide Ion ◽  
Rate Limiting

Rate constants of base-catalyzed methanolysis and dissociation constants in methanol have been determined for benzoylthiourea (II), 1,3-diacetylthiourea (III), 1,3-dibenzoylthiourea (IV), and 1-acetyl-3-benzoylthiourea (V). With the diacyl derivatives III and IV, the reaction of methoxide ion with the neutral substrate is accompanied by that of methoxide with the substrate anion (at higher alkoxide concentrations). Above 0.1 mol l-1 CH3O(-), the rate constants are also affected by medium. The rate of the reaction of neutral diacyl derivative is decreased, and that of the reaction of methoxide with the substrate anion is rapidly increased. The dissociation constant of II is higher than that of acetylthiourea (I) by about one order of magnitude, but the attack of methoxide on the carbonyl group of II is about three times slower than that in I. The benzoyl group at the N1 nitrogen exhibits a greater activating influence (in both the rate and the equilibrium constants) on the other NHCOR group than the acetyl group does. With V the ratio of methanolysis rate constants is 9 : 1 in favour of the acetyl group. The reaction of diacetyl derivative III with 1-butanamine has been followed in butanamine buffers. At the lowest butanamine concentrations, the reaction is second order in the amine, and the rate-limiting step is the proton transfer from the intermediate to the second amine molecule. At the highest butanamine concentrations the reaction becomes first order in the amine, and the rate-limiting step changes to the attack of butanamine on the carbonyl group of diacetyl derivative III.

Kinetics and mechanism of methanolysis of benzoyl derivatives of substituted phenylureas and phenylthioureas

1984 ◽  
Vol 49 (9) ◽  
pp. 2103-2110 ◽  
Author(s):  
Jaromír Kaválek ◽  
Said El Bahaie ◽  
Vojeslav Štěrba
Keyword(s):  
Nitrogen Atom ◽  
Steric Hindrance ◽  
Rate Constants ◽  
Dissociation Constants ◽  
Kinetics And Mechanism ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Order Of Magnitude ◽  
Rate Limiting ◽  
Derivatives Of

The methanolysis rate constants and dissociation constants have been measured of benzoyl derivatives of substituted phenylureas and phenylthioureas. The dissociation constants of the thio derivatives are higher by 1 order of magnitude and the rate constants are higher by 2 orders of magnitude than the respective values of the oxygen analogues. Logarithms of the rate and dissociation constants have been correlated with the Hammet σ constant; the ρ constant of the methanolysis of the oxygen derivatives is almost 2x higher than that of the thio derivatives, which is explained by a change in the rate-limiting step. Methylation of the phenyl nitrogen atom increases the acidity by almost 2 orders of magnitude. This effect is due obviously to steric hindrance to the conjugation with the adjacent carbonyl or thiocarbonyl group.

A Theoretical Investigation on the Structure of Fan Wakes

1978 ◽  
Vol 100 (1) ◽  
pp. 113-119 ◽  
Author(s):  
R. Raj ◽  
J. L. Lumley
Keyword(s):  
Decay Rate ◽  
Theoretical Investigation ◽  
Axial Velocity ◽  
Analytical Study ◽  
Turbulence Structure ◽  
Relative Order ◽  
Turbulent Characteristics ◽  
Order Of Magnitude ◽  
The Mean ◽  
Insight Into

An analytical study is presented of the mean and turbulent characteristics of axial turbulent wakes behind a rotating fan. Simplified solutions are presented governing the mean radial and axial velocity profiles and their decay rate. An estimate is made of the relative order of magnitude of various turbulence quantities. The effect of rotation on the turbulence structure is described. Sufficient physical interpretations and explanations are presented for insight into and formulation of the problem.

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