In this study, the thermal behavior of butanediol isomers is investigated for temperatures ranging from 103 to 303 K using
differential scanning calorimetry, complemented, when necessary, by polarized light thermal microscopy. The butanediol isomers
display quite different thermal behaviors: for 1,2- and 1,3-isomers, glass transition is the only thermal event observed;
for 1,4-butanediol, crystallization occurs on cooling even at a high scanning rate and no glass formation was detected; and
for the 2,3-isomer, glass or crystal formation is dependent on the experimental conditions employed. The glass-forming ability
of the isomers is correlated with data available on their molecular symmetry.
The enthalpies, entropies and Gibbs energies of inclusion of dl-1,3-, 1,4- and meso-2,3-butanediols into α- and β-cyclodextrin cavities from ideal gas phase have been determined on the basis of newly obtained
experimental data of the butanediols. The butanediol molecules are stabilised strongly in the cavities due to interactions
with inner walls of the cavities. Entropies of the gaseous isomers are greatly decreased in the cavities. The largest decrease
is obtained for the case of 2,3-BD. Discussions concerning the1,4-butanediol given in the preceding paper have been changed
due to the adoption of new data on the butanediols.
The enthalpies of transfer 2-propanol, 1,2-butanediol (BD) and 1-hexanol from aqueous to aqueous α-cyclodextrin (CD) solutions
have been determined by microcalorimetry at various mole fractions at 298.15 K. To clarify stabilities of inclusion complexes
in aqueous solutions, hydration Gibbs energies calculation of inclusion complex of CD-alcohol were performed by using the
molecular mechanics with the MMFF94s force field in the generalized born/surface area (GB/SA) model. The largest stabilization
in Gibbs energy is obtained by the hydration (ΔhydH) of α-CD-1,2-butanediol complex among α-CD-butanediol isomers complexes.
The enthalpies of dilution of aqueous solutions of methanol, ethanol, l-propanol, 2-propanol, 1-butanol, l-pentanol, 1-hexanol,
cyclohexanol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol and poly-alcohol(cyclohexaamylose) have been determined at high
dilution as a function of the mole fraction of alcohol at 298.15 K, by a rocking twin-microcalorimeter of the heat-conduction
A smoothing equation of the enthalpies of dilution against the mole fractions of alcohols are given. The graphical comparison
of experimental results with their smoothed values or literature ones, taking into account the dependence of the mole fractions,
are also presented.
It has been found for the aqueous solutions of shorter n-alcohols than hexanol that at very high dilution, exothermic values of molar enthalpies of dilution from a definite mole
fraction of alcohols to infinite dilution with the change of mole fraction is proportional to carbon number of n-alcohols. The molar enthalpies of infinite dilution of aqueous butanediol isomers and 1-hexanol were very large. Molar enthalpies
of infinite dilution of aqueous poly-alcohol (cyclohexaamylose) were endothermic.