Ultrasonic and¹³C N.M.R. studies of isomeric octanols

Abstract

Ultrasonic and 13C N.M.R. data are reported for l-octanol, 2-octanol, 2,3-dimethyl-3-hexanol and 2,4-dimethyl-3-hexanol. The ultrasonic relaxation data indicate that in 1-and 2-octanol the observed dispersion can be attributed to hydrogen bond exchange processes associated with structural relaxation of the liquid. For 2,3-dimethyl-3-hexanol and 2,4-dimethyl-3-hexanol, an additional contribution associated with internal rotational relaxational processes has been detected. Assignments of the observed 13C spectra are compared with the predictions of the theory developed by Grant and Paul. Activation parameters obtained from the laC and ultrasonic studies are compared with those obtained from the temperature dependence of viscous flow. The conformational changes are discussed in terms of the effects of steric and polar contributions to the internal rotational potential.

Structural Properties of 1-Octanol/n-Octane Mixtures Studied by Brillouin Scattering

“…This work confirms previous literature studies 3,5 performed at room temperature and enhances the knowledge about the behavior of the 1-octanol/n-octane system in the temperature range of 5-70 °C and in the GHz domain.…”

“…The role played by the strength of H-bonding in the structure and stability of local aggregates of n -alcohols has been recognized for a long time. − It has also been established that the strength of this intermolecular interaction inversely scales with the length of the alkylic chain. More stable aggregates are found in alcohols with a shorter alkylic tail, and the bond forces due to the O−H group interactions prevail over those of the hydrocarbon chain.…”

“…In a series of articles mostly from the 1980s, − ,, the intermolecular forces of alcoholic liquid systems were explored, to distinguish the effects of hydrogen bonding from those due to the methylenic chain. The changes in molecular structure, linear or branched, were explored, and the effect of the steric hindrance of the hydrogen-bonding network was shown.…”

Comparison of Hydrogen Bonding in 1-Octanol and 2-Octanol as Probed by Spectroscopic Techniques

“…The strength of the hydrogen bond interactions, the degree of self-association, and the geometrical arrangements of local environments in the liquid state are in some way correlated with the length and branching of the hydrocarbon tail and with the different exposure of the OH group. − The same molecular factors also regulate relaxation processes and dynamical properties of the liquid systems. − In amphiphilic molecules, two types of forces take part in determining overall liquid organization, namely, the dispersion forces concentrated on the hydrocarbon tails (i.e., “hydrophobic”) and the dipolar electrostatic ones localized on the OH groups (i.e., “hydrophilic”). These forces are correlated, and their interplay, determining the structure and the dynamics of the liquid at molecular scales, modulates its macroscopic properties.…”

“…[1][2][3][4][5][6][7] The same molecular factors also regulate relaxation processes and dynamical properties of the liquid systems. [8][9][10][11] In amphiphilic molecules, two types of forces take part in determining overall liquid organization, namely, the dispersion forces concentrated on the hydrocarbon tails (i.e., "hydrophobic") and the dipolar electrostatic ones localized on the OH groups (i.e., "hydrophilic"). These forces are correlated, and their interplay, determining the structure and the dynamics of the liquid at molecular scales, modulates its macroscopic properties.…”