Gibbs free energy of hydrogen bonding of aliphatic alcohols with liquid water at 298 K

Thermodynamics of hydrogen bonding between water and molecules of aliphatic alcohols in dilute aqueous solutions is studied. The Gibbs free energies of hydrogen bonding of normal aliphatic alcohols from methanol to octanol with liquid water are determined from experimental data. The molar fractions of free unbonded molecules of alcohols and monomeric species of water are reported. Strong cooperative effects are observed when an alcohol molecule binds to an associate of water, leading to huge negative values of the Gibbs energies and an increased aqueous solubility. Formation of the second and third hydrogen bonds of an alcohol molecule with water is much less favorable, what can be described as an anti-cooperative effect.

► ΔG of H-bonding of C1–C8 alcohols with liquid water at 298 K are determined.
► H-bond of alcohol with bulk H2O is much stronger than with a single H2O molecule.
► Second and third H-bonds of ROH molecule with water are weaker than the first one.