Structure and Physicochemical Properties of Acetonitrile–o-Dichlorobenzene Solutions
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Based on an analysis of concentration dependences of the degree of depolarization and molecular light scattering coefficients, density, ultrasound speed, adiabatic compressibility, excess molar volume and adiabatic compressibility in acetonitrile–о-dichlorobenzene solutions, three ranges with different structures are distinguished: 0–0.2, 0.2–0.9, and 0.9–1.0. Molecular dynamics modeling is performed in each range to obtain a detailed description of the structure of the solutions. It is found that in the first range, the solvation of acetonitrile molecules is accompanied by the local reorientation of о-dichlorobenzene molecules from mainly parallel to mainly perpendicular arrangement. The acetonitrile molecules fall into less dense regions of the о-dichlorobenzene structure and are incorporated into the system of its nonvalent contacts. The second range is the region of the maximum heterogeneity of the solutions, in which an important role is played by both homo- and heteromolecular interactions, and there are agglomerates and conglomerates of the molecules of both components. In the third range, о-dichlorobenzene molecules are solvated, and the mechanism differs from that of the solvation of acetonitrile: о-dichlorobenzene weakly affects the acetonitrile structure and its structure remains virtually unchanged.
Keywords:acetonitrile о-dichlorobenzene local structure of a liquid molecular light scattering ultrasound speed isothermal compressibility radial-angular distribution function (RADF) distances radial distribution function for distances (RDF), molecular dynamics modeling
The authors thank L.V. Lanshina for her critical appraisal of the results in this work.
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