Partial molar volumes of linear hydrocarbons in methanol in the very dilute region. Intermolecular interactions. H-bond effects

Partial molar volume of tertiary amines in methanol at T=298.15K. Solvation, shape and specific interactions

“…Table 4 shows that, b V values turn from positive to negative going with the increasing size of the amines. Negative values for the latter group of amines would stand for the attractive solute-solute short-range interactions as already observed in the case of linear hydrocarbons [21]. Figure 2 shows the evolution of b V values with the chain length of the amines, represented by the number of carbon atoms, n C .…”

“…These features might be the specific H-bonding interaction between the lone electron pair of the amine and the hydroxyl group of the methanol, the attractive solute-solute short range interactions and the destruction of the methanol structure. This latter effect, that was previously proved to exist for the linear hydrocarbons [21], would correspond to a considerable increase in the molar volume of methanol contained in the solvating shell of the solute. The positive and negative contributions seem to almost cancel out in the case of Bu 3 N.…”

“…In a previous study [21], where V 1 B of linear hydrocarbons (C 5 to C 10 ) in methanol were experimentally determined, we have used Lee's model [10] to show that when linear hydrocarbons are introduced in methanol there is a loss of favourable methanolmethanol interactions (H-bonds) leading to a decrease in the methanol packing density. We have also shown that this same model accounted for the experimental V 1 B values then obtained for linear hydrocarbons, provided that a correct value for the molar volume of that ''new methanol'', called by us ''non H-bonded methanol'' is introduced into the calculations.…”

“…The hard-sphere mixture model, obeying to the accurate equation of state by Mansoori et al [12] and the ''non-bonded methanol'' approach, proposed by us in a previous work [21], has been used to the end of understanding and quantifying assigned contributions for V 1 B . Quantitative measures of the volumetric interaction parameters for six tertiary amines, triethylamine, Et 3 N, tri-n-propylamine, Pr 3 N, tri-n-butylamine, Bu 3 N, tri-n-pentylamine, Pent 3 N, tri-n-hexylamine, Hex 3 N and tri-n-octylamine, Oct 3 N were obtained.…”

Volumetric Properties of Aqueous Solutions of Ethylene Glycols in the Temperature Range of 293.15–318.15 K

“…Experimental densities for the various binary mixtures in the molality ranges studied obey equation of the type [13] = + + 2 .…”