Coordinating properties of pyrrolic and pyridinic nitrogen with metals in aqueous solution. A calorimetric study

1981 ◽  
Vol 34 (3) ◽  
pp. 501 ◽  
Author(s):  
R Aruga
Keyword(s):  
Equilibrium Constants ◽  
Carboxylate Ligand ◽  
Calorimetric Study ◽  
Thermodynamic Quantities ◽  
Gibbs Function ◽  
Direct Calorimetry ◽  
Enthalpy Of Complex Formation ◽  
Pyridinic Nitrogen ◽  
Enthalpy Data ◽  
Nitrogen Bond

Enthalpy of complex formation of pyrrole-2-carboxylate ligand with calcium(II), cobalt(II), nickel(II) and copper(II) cations has been determined by direct calorimetry. By means of the equilibrium constants, Gibbs function and entropy were also obtained. The measurements were carried out in aqueous medium at 25�C and an ionic strength of 1 (NaNO3). The thermodynamic quantities for pyrrole-2-carboxylate, compared with those for pyridine-2-carboxylate obtained previously, lead to the following conclusions. (A) The enthalpy factors which make the metal-pyridinic ligand complexes rather stable are absent in the case of pyrrolic ligand. The absence is probably due to the electronic structure of the pyrrole aromatic ring. (B) The enthalpy data seem to indicate, for the metal complexes of pyrazole and imidazole, a metal-pyridinic nitrogen bond rather than a metal-pyrrolic nitrogen bond.

Solute–solvent interactions in the association of hexacyanoferrate(III) with group II A cations. A calorimetric study

1982 ◽  
Vol 60 (14) ◽  
pp. 1828-1831 ◽  
Author(s):  
Roberto Aruga
Keyword(s):  
Equilibrium Constants ◽  
Ion Pairs ◽  
Ion Pair ◽  
Pair Formation ◽  
Calorimetric Study ◽  
Thermodynamic Quantities ◽  
Gibbs Function ◽  
Direct Calorimetry ◽  
Solvent Interactions ◽  
Enthalpy Of Association

Enthalpy of association of hexacyanoferrate(III) ion with Mg(II), Ca(II), Sr(II), and Ba(II) cations has been determined by direct calorimetry. Using the equilibrium constants, Gibbs function and entropy were also obtained. Measurements were carried out in aqueous medium at 25 °C and ionic strength I = 0.1 mol L−1. Examination of the thermodynamic quantities obtained and calculation of the distance of closest approach between cation and anion show the presence of different desolvation processes for the metals studied. More particularly, solvent-separated ion pairs in the case of magnesium and contact pairs in the case of barium seem to be present. The presence of desolvation processes is uncertain for calcium and strontium. The ΔH0 and ΔS0 values show also an important influence from solvent-destructuring processes on ion pair formation.

Coordinating Properties of Aromatic and Aliphatic Sulfur with Bivalent Metals in Aqueous Solution. A Calorimetric Study

1979 ◽  
Vol 32 (4) ◽  
pp. 709 ◽  
Author(s):  
R Aruga
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Complex Formation ◽  
Aqueous Medium ◽  
Formation Constants ◽  
Calorimetric Study ◽  
Thermodynamic Quantities ◽  
Direct Calorimetry ◽  
Bivalent Metals

Heats and entropies of complex formation of the thiophen-2-carboxylate ion with Ni2+, Cu2+, Zn2+ and Cd2+ have been determined by direct calorimetry, the formation constants being known from the literature. The measurements were carried out in aqueous medium at 25�C and an ionic strength of 1. The values of the thermodynamic quantities for thiophen-2-carboxylate, compared with those for (ethylthio)acetate and (phenylthio)acetate obtained previously, indicate a greater tendency for aromatic sulfur to form bonds with the above metals than for aliphatic sulfur. The causes of this behaviour are discussed.

Proton dissociation of aqueous organic acids studied by multivariate chemometrics

1995 ◽  
Vol 73 (12) ◽  
pp. 2170-2177 ◽  
Author(s):  
Roberto Aruga
Keyword(s):  
Principal Component Analysis ◽  
Factor Analysis ◽  
Organic Acids ◽  
Principal Component ◽  
Component Analysis ◽  
Acid Dissociation ◽  
Multivariate Techniques ◽  
Thermodynamic Quantities ◽  
Gibbs Function ◽  
Proton Dissociation

Thermodynamic data of proton dissociation of 75 organic acids belonging to four classes (protonated amines, aliphatic carboxylic acids, benzoic acids, phenols) have been processed by multivariate chemometric techniques. The variables consist of conventional thermodynamic quantities (Gibbs function, enthalpy, entropy) and of partial components of these quantities (internal and external, electrostatic and nonelectrostatic components). The above data refer to the aqueous medium, at 25 °C and I = 0 mol dm−3. The Gibbs function of deprotonation in the gas phase and the Hammett σ constant have also been considered. Multivariate techniques include Principal Component Analysis, Factor Analysis, and feature selection. Factor Analysis and related concepts have proved to be useful in defining the causes of differences in acid strengths and their respective importance. Keywords: acid dissociation data, chemometrics of; chemometrics of acid dissociation data; factor analysis of acid dissociation data; principal component analysis of acid dissociation data; thermodynamics of acid dissociation.

scholarly journals Kinetics and Mechanistic Study of Permanganate Oxidation of Fluorenone Hydrazone in Alkaline Medium

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Ahmed Fawzy ◽  
Saleh A. Ahmed ◽  
Ismail I. Althagafi ◽  
Moataz H. Morad ◽  
Khalid S. Khairou
Keyword(s):  
Ionic Strength ◽  
Alkaline Medium ◽  
Equilibrium Constants ◽  
Activation Parameters ◽  
Active Species ◽  
Mechanistic Study ◽  
Thermodynamic Quantities ◽  
Rate Limiting Step ◽  
Expression Rate ◽  
Reaction Constants

The oxidation kinetics of fluorenone hydrazone (FH) using potassium permanganate in alkaline medium were measured at a constant ionic strength of 0.1 mol dm−3 and at 25°C using UV/VIS spectrophotometer. A first-order kinetics has been monitored in the reaction of FH with respect to [permanganate]. Less-than-unit order dependence of the reaction on [FH] and [OH−] was revealed. No pronounced effect on the reaction rate by increasing ionic strength was recorded. Intervention of free radicals was observed in the reaction. The reaction mechanism describing the kinetic results was illustrated which involves formation of 1 : 1 intermediate complex between fluorenone hydrazones and the active species of permanganate. 9H-Fluorenone as the corresponding ketone was found to be the final oxidation product of fluorenone hydrazone as confirmed by GC/MS analysis and FT-IR spectroscopy. The expression rate law for the oxidation reaction was deduced. The reaction constants and mechanism have been evaluated. The activation parameters associated with the rate-limiting step of the reaction, along with the thermodynamic quantities of the equilibrium constants, have been calculated and discussed.

Equilibrium constants for σ-complex formation between cyanide ion and 1,3,5-trinitrobenzene in alcoholic solvents

1969 ◽  
Vol 47 (22) ◽  
pp. 4129-4133 ◽  
Author(s):  
E. Buncel ◽  
A. R. Norris ◽  
W. Proudlock ◽  
K. E. Russell
Keyword(s):  
Complex Formation ◽  
Equilibrium Constant ◽  
Equilibrium Constants ◽  
Primary Factor ◽  
Aprotic Solvents ◽  
Kcal Mole ◽  
Cyanide Ion ◽  
Direct Calorimetry ◽  
Entropy Changes ◽  
Enthalpy Changes

Equilibrium constants have been determined spectrophotometrically for the reaction of cyanide ion with 1,3,5-trinitrobenzene in methanol, ethanol, n- and iso-propanol, and n- and t-butanol. The equilibrium constants at 25 °C vary from 39 1 mole−1 for the reaction in methanol to 500 000 1 mole−1 with t-butanol as solvent. Enthalpy changes, determined from equilibrium measurements and by direct calorimetry, vary from 0 to −15.5 kcal mole−1 and the calculated entropy changes decrease from 7 to −26 cal deg−1mole−1 as the solvent is changed from methanol to t-butanol. These results are interpreted on the basis that desolvation of the small cyanide ion is the primary factor influencing enthalpies and entropies of reaction. The equilibrium constant in t-butanol is comparable to the values observed for aprotic solvents such as chloroform and acetone.

The sorption of krypton and xenon in zeolites at high pressures and temperatures II. Comparison and analysis

1972 ◽  
Vol 326 (1566) ◽  
pp. 331-345 ◽  
Keyword(s):  
High Pressures ◽  
Equilibrium Constants ◽  
Sorption Isotherms ◽  
Rare Gas ◽  
Thermodynamic Quantities ◽  
Zeolite A ◽  
Temperature Coefficients ◽  
High Pressures And Temperatures ◽  
High Temperature High Pressure ◽  
Gas Pressures

Absolute and Gibbs excess sorption isotherms of Kr and Xe have been measured at a range of temperatures between 0 and 450 °C and at high pressures in zeolites X and Y (near-faujasites); zeolite A; H-Zeolon and Na-Zeolon (near mordenites); chabazite; and an active carbon, to compare their efficiencies in reducing the rare gas pressures in high-temperature, high-pressure systems. At 450 °C the best sorbents for the purpose were chabazite and the carbon. The isotherms have been analysed to give distribution equilibrium constants for absolute sorption and associated standard thermodynamic quantities (Δ A ⊖ , Δ E ⊖ and Δ S ⊖ ). Isosteric heats have been derived and compared as functions of amount sorbed both for absolute and for Gibbs excess uptakes. These heats differ substantially for larger uptakes, but converge as the uptake decreases. Differential entropies of the intracrystalline rare gas have been calculated for absolute sorption. They decline monotonically with amount sorbed and have temperature coefficients which appear not very different from values expected for classical oscillators.

Ion Pairing and the Reaction of Alkali Metal Ferrocyanides and Persulfates

1971 ◽  
Vol 49 (18) ◽  
pp. 2943-2947 ◽  
Author(s):  
R. W. Chlebek ◽  
M.W. Lister
Keyword(s):  
Alkali Metal ◽  
Rate Constants ◽  
Equilibrium Constants ◽  
Ion Pairs ◽  
Activation Parameters ◽  
Ion Pairing ◽  
Similar Rate ◽  
Thermodynamic Quantities ◽  
Kinetics Of

Osmometric measurements have been made on the alkali metal persulfates, and these are interpreted in terms of formation of ion pairs, MS2O8−, by means of the method of Masterton and Berka (5). Equilibrium constants, and the derived thermodynamic quantities are deduced for the reactions [Formula: see text]. These results are applied to the interpretation of the kinetics of the reactions[Formula: see text]With M = K+, Rb+, and Cs+, the reacting species are MFe(CN)63− + MS2O8−, with very similar rate constants; with M = Li+, Na+ the species are MFe(CN)63− + S2O82−; and for lithium the reaction of Fe(CN)64− + S2O82− is also important. Rate constants and activation parameters are deduced.

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