Ultrasonic and Volumetric Investigation of Aqueous Solutions of Amides

Abstract

The ultrasonic velocity and density of aqueous solutions of N-methylformamide, N,N-dimethylformamide, and N,N-dimethyIacetamide have been measured at 25 and 35 °C over the entire concentration range. The compressibility, excess compressibility, partial molar compressibility, partial molar volume, and pressure dependence of the partial molar volume have been calculated. The concentration dependences of the velocity and density are highly nonlinear, and the velocity maxima are observed in all the amide solutions at ca. 20 mol%. Minima in the partial molar volume exist in solutions of DMF and DMAA, but not in that of MFA. On taking account of the results for viscosity, the velocity maxima are ascribed to the complex formation, and the minima in the partial molar volume, to the competition between the volume increase due to the complex formation and the volume decrease due to the breaking-down of the water structure. The pressure dependence of the partial molar volume shows that amides and water have strong interactions, even in the low-mole-fraction regions for each component.

Molecular interactions in binary mixtures of formamide with 1-butanol, 2-butanol, 1,3-butanediol and 1,4-butanediol at different temperatures: An ultrasonic and viscometric study

“…2) for all the four binary systems over the entire mole fraction range and at all investigated temperatures and follow the order: 1-butanol > 2- butanol > 1,3-butanediol > 1,4-butanediol. The magnitude of u values has been considered as an indicator of the strength of the intermolecular interaction between unlike molecules in the mixture [34,35]. In general, the strength of interactions decrease with increasingly negative u values.…”

Volumetric properties of binary mixtures of N, N- dimethylformamide with water or water- d2 at temperatures from 277.13 K to 318.15 K

“…The complex formation gives rise to an increase in the apparent molar volume of DMF because the complex formed by the hydrogen bonding between DMF and water has a rigid, bulky structure. (89) Considering the water-rich region, the minimum in the plots of V E (DMF) against x(H 2 O or D 2 O) {figure 5(a)-5(f)} may be attributed to the competition between the volume decrease due to the breakdown of water structure in the vicinity of the DMF molecules and the volume increase due to the complex formation. (89) The degree of hydrogen bonding in liquid D 2 O is greater than in liquid H 2 O and the hydrogen bonds between D 2 O molecules are stronger than those between H 2 O molecules.…”

“…(89) Considering the water-rich region, the minimum in the plots of V E (DMF) against x(H 2 O or D 2 O) {figure 5(a)-5(f)} may be attributed to the competition between the volume decrease due to the breakdown of water structure in the vicinity of the DMF molecules and the volume increase due to the complex formation. (89) The degree of hydrogen bonding in liquid D 2 O is greater than in liquid H 2 O and the hydrogen bonds between D 2 O molecules are stronger than those between H 2 O molecules. (90) Also, the hydrogen bonds of D 2 O between DMF are stronger than those of H 2 O between DMF.…”

Ultrasonic Investigations of Inclusion Complexation of α-Cyclodextrin by DMSO in Pseudo-Binary Aqueous System

“…1). Kawaizumi et al (1997) explain the appearance of a maximum in the ultrasonic speed with the formation of free complexes in the solution, and the position of maximum velocity indicates the type and composition of the complexes.…”