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The specific features of clustering in the aqueous solutions of monohydric alcohols with concentrations higher than that at the peculiar point are discussed. Clustering is a result of the formation of hydrogen bonds between water and alcohol molecules, the energy of which somewhat exceeds the energy of hydrogen bonds in the water-water and alcohol-alcohol molecular pairs. Elementary clusters are assumed to be formed, whose composition is fixed at the solution concentrations lower than that at the peculiar point and changes according to a certain law at higher concentrations. The solution clustering degree was determined as a function of the solution concentration and the temperature.K e y w o r d s: solutions, water, monohydric alcohols, elementary clusters, peculiar point. IntroductionThe properties of aqueous monohydric alcohol solutions differ substantially from the properties of ideal solutions [1][2][3]. This difference reveals itself in the optical properties of solutions, in particular, in the appearance of maxima in the abnormal light scattering [4][5][6], in the form of the concentration and temperature dependences of the adiabatic compressibility [7] and the heat capacity [8], in the emergence of large relaxation times [2,9] and other features in the volumetric behavior of those solutions [10,11], in particular, their contraction [12][13][14].The first models of solutions as associated systems were developed by D.I. Mendeleev more than 150 years ago after the systematic studies of clustering in water-alcohol solutions [15]. This concept was developed and detailed in further researches, both experimental and theoretical ones, which had been reflected in a number of reviews [1,16]. In particular, Scatchard [17], using thermodynamic methods, studied the volume change at the solution formation from its components.In works [12][13][14], the manifestation of clustering in the behavior of the simplest solution characteristic,

The dynamics of the thermodynamic equilibrium establishment in the aqueous solutions of alcohols in a vicinity of specific points is studied on the basis of dilute aqueous solutions of glycerol. At the molar fractions of alcohol 𝑥 ∼ 0.05, the systems concerned reveal characteristic anomalies testifying to the presence of structural phase transitions. However, the unreliable reproducibility of anomalous light scattering, a phenomenon typical of aqueous alcohol solutions, makes this conclusion debatable. In this work, it was shown that the parameters of aqueous glycerol solutions, which are determined with the help of light scattering phenomenon, become stable only in a certain time interval after the solution preparation. The typical dimensions of optical non-uniformities, the coefficients of scattered light depolarization, and the asymmetry of scattering indicatrix have been found as functions of the time elapsed since the solution preparation.K e y w o r d s: anomalous light scattering, dilute alcohol aqueous solutions, glycerol, thermodynamic equilibrium.

Specific features of the clustering in aqueous solutions of monoatomic alcohols have been discussed. Main attention is focused on details of the clustering in water-ethanol solutions. The clustering degree is supposed to depend on the nteraction between ethanol and water molecules, as well as on the ordering degree of the H-bond network in water, which changes with the temperature and concentration of the alcohol. The elementary cluster volume is assumed to be smaller than the sum of the molecular volumes of components that form this cluster. The clustering degree in aqueous solutions of methanol and ethanol and its concentration and temperature dependences are determined.

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