Extraordinary Properties of Alcohols from the Homologous Series of Methanol

Abstract

Non-trivial properties of thermodynamic quantities such as the density, the critical and triple point temperatures, and their ratio, as well as the optical and dielectric properties, have been analyzed for primary alcohols from the methanol series. The aim is to reveal relationships among their values measured at the same temperatures for alcohols with different ordinal numbers m’s in the methanol series. It is shown that the non-monotonic character of the temperature dependences of alcohol densities is associated with methanol rather than ethanol, as may seem at first glance. The critical temperature of methanol also deviates from the quasilinear dependence of the critical alcohol temperatures on m. With the growing m, the ratio between the critical and triple-point temperatures for alcohols is shown to tend to the corresponding value for water. Simple linear dependences of the electronic and effective static polarizabilities of alcohol molecules on m are established. The transverse and longitudinal components of the polarizability tensor for alcohol molecules are found. The dipole moments of the closest neighbor molecules in the alcohols are proved to anticorrelate, i.e. to orient in opposite directions.

The Global Polarity of Alcoholic Solvents and Water – Importance of the Collectively Acting Factors Density, Refractive Index and Hydrogen Bonding Forces

“…In addition, the position of the OH group also seems to be characteristic. [1,3,[23][24][25] Thus, the decrease of n 20 D as a function of N is more pronounced for tertiary alcohols than for primary or secondary ones indicating a higher oscillator strength and/or a stronger coupling of the solvent oscillators with those of the solute and consequently a stronger redshift in accordance with the previous study. [8a] The high significance of the correlations is impressive and indicates reliable relationships (Figure 2).…”

“…It is assumed that the effective D HBD values for secondary and tertiary alcohols are lower than for the primary alcohols by a certain factor because of their different liquid structures [1,3,23–25] . It is predicted that a hypothetical factor f , that determines the efficiency of OH dipolar group action, depends on their position along the alkyl chain according to Ref.…”

“…It is assumed that the effective D HBD values for secondary and tertiary alcohols are lower than for the primary alcohols by a certain factor because of their different liquid structures. [ 1 , 3 , 23 , 24 , 25 ] It is predicted that a hypothetical factor f , that determines the efficiency of OH dipolar group action, depends on their position along the alkyl chain according to Ref. [1] We have assumed that this is the case and simply calculated the factor f for several monohydric secondary and tertiary as well as polyhydric alcohols from the deviation of the excellent linear relationship given by Equation (5).…”

“…The limitation of D HBD concerns the positions and arrangement of the OH substituents in a given volume, which determine their actual effectiveness, as shown by several physical studies on different types of alcohols. [ 1 , 22 , 23 , 24 , 25 ] The electromagnetic coupling of the solvent's oscillators located in the UV/Vis region with those of the dye plays an important role. [26] This aspect is treated in particular in this work, since the position of the OH group and the carbon skeleton of the alcohol derivative also strongly influence the oscillator strength.…”

“…The limitation of D HBD concerns the positions and arrangement of the OH substituents in a given volume, which determine their actual effectiveness, as shown by several physical studies on different types of alcohols [1,22–25] . The electromagnetic coupling of the solvent's oscillators located in the UV/Vis region with those of the dye plays an important role [26] .…”