Dimerization and continuous association including formation of cyclic dimers

Abstract

A. APELBLAT. Can. J. Chem. 69, 638 (1991). New aspects of the theory of ideal associated mixtures related to a differentiation between formed cyclic and linear dimers are discussed. A mathematical analysis is presented for the dimerization model, A + B + A', the continuous association (Mecke-Kempter) model, A + B + A 1 + A3 + A4 + . . ., both coupled with the cyclic dimer 4 linear dimer transformation and for the unsymmetrical (mixed) dimer formation model, A + B + A ? + B2 + AB. Introduction of the standard reaction enthalpies and volumes associated with transformations of dimers leads to a considerable change in behavior and symmetry properties of the excess thermodynamic functions. In terms of the modified Mecke-Kempter model, a consistent representation of the excess Gibbs energy of mixing G~, heat of mixing H E , and excess molar volume vE is reported for the acetic acid -water system at 298.15 K.Key words: association, dimerization, linear dimers, cyclic dimers, hydrogen bonding, carboxylic acids, alcohols, aqueous solutions.A. APELBLAT. Can. J. Chem. 69, 638 (1991). On discute de nouveaux aspects de la thtorie des mtlanges associts parfaits qui sont relies ?i une difftrentiation entre la formation de dimbres cycliques et lintaires. On presente une analyse mathtmatique du modble de dimtrisation, A + B + A 2 , du modble d'association continue (Mecke-Kempter), A + B + A2 + A3 + A4 + . . ., ainsi que deux modbles couplts avec la transformation du dimkre cyclique 4 dimbre lineaire et finalement du modble de formation du dimbre asymttrique (mixte), A+ B+A2+B2+AB. L'introduction des enthalpies standard de reaction et des volumes associts avec les transformations des dimbres conduit B un changement important dans le comportement et les propriites de symttrie des fonctions thermodynamiques en excbs. Pour le systbme acide acttiqueleau, ?i 298,15 K et utilisant le modtle de Mecke-Kempter modifii, on a obtenu une reprtsentation coherente de l'tnergie de mtlange de Gibbs en excbs, G~, de la chaleur de formation, HE et du volume molaire en excbs, vE.

Functional transformation of Fourier-transform mid-infrared spectrum for improving spectral specificity by simple algorithm based on wavelet-like functions

“…Dimerization of acetic acid has been widely evaluated [19] , [22] . Usually the dimerization phenomenon is easily described in dissolution of acetic acid in aprotic polar solvents; and it can be understood as the formation of molecular association by hydrogen bonds between acid proton on carboxylic acid group and electronegative oxygen on carbonyl group ( Fig.…”

“…To study dimerization of acetic acid, the following dimerization reaction is assumed 2CH 3 COOH CH 3 COOH⋯HOOCCH 3 ; where “⋯” denotes the hydrogen bond formation [19] . Thus, dimerization constant ( K D ) can be easily calculated by where x is the amount dimerized acetic acid and C 0 is the acetic acid initial concentration, and [dimer] and [monomer] are the concentrations are dimer and monomer at equilibrium, respectively.…”

“…Thus, dimerization constant ( K D ) can be easily calculated by where x is the amount dimerized acetic acid and C 0 is the acetic acid initial concentration, and [dimer] and [monomer] are the concentrations are dimer and monomer at equilibrium, respectively. From infrared data, x can be easily calculated by where a 1 and a 2 are the absorbance values associated to monomer and dimer, respectively [19] .…”

The vapour pressures over saturated aqueous solutions of cadmium chloride, cadmium bromide, cadmium iodide, cadmium nitrate, and cadmium sulphate

“…In the continuation of studies on vapour pressure of water over saturated solutions of electrolytes having industrial or biological importance [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15], a number of cadmium salts are considered. Cadmium compounds (usually very toxic) are used in metal plating, battery industry, photography, catalysis, dyeing, and printing industries [16].…”

The vapour pressures over saturated aqueous solutions of sodium and potassium acetates, chlorates, and perchlorates

“…In the continuation of studies on vapour pressure of water over saturated solutions of electrolytes having industrial or biological importance [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15], the acetates, chlorates, and perchlorates of sodium and potassium are considered. The knowledge of vapour pressures when expressed in hygroscopic terms (relative humidity) is important in handling, storage, shipping, and purity of compounds as well as in providing constant humidity in enclosed spaces.…”