Chemistry Reference
In-Depth Information
∆
G
11
∆
G
22
∆
G
33
200
100
100
100
1
75
0
3
0
50
2
-100
-100
25
-200
-200
-300
0
∆
G
12
∆
G
13
∆
G
23
0
400
-20
-25
300
-40
-50
200
-60
-75
100
-80
-100
-100
0
FIGURE 4.3
Corrected KBIs (Δ
G
ij
, Equation 4.29) for the ternary system trichloromethane(1)
+ tetrahydrofuran(2) + cyclohexane(3) at 298.15 K. Units are cm
3
mol
-1
. For all pictures,
components correspond to the three corners of the composition triangle as illustrated in the
first panel.
4.6.1 K
irKwood
-B
uFF
i
inTegrals
The main features that first appear after looking at Figure 4.1 are the very high
positive values of Δ
G
11
, which reach a maximum of 14 dm
3
mol
-1
in the cyH-rich
area of the binary Et+cyH, at
x
1
≈ 0.1. These values greatly surpass the also high
values of Δ
G
12
, which almost parallel Δ
G
11
, and the small but always positive values
of Δ
G
22
. Δ
G
33
is also positive in the whole domain, with the largest values in the Et-
rich area. Δ
G
13
is fairly strongly negative with a minimum in the cyH-rich region of
the Et+cyH binary. Δ
G
23
shows either positive or negative values, but is always very
small in magnitude like Δ
G
22
.
These trends suggest that the interaction that dominates is the associative attraction
Et-Et, which is much stronger than the hetero-association Et-THF. The relatively high
values of Δ
G
12
indicate that this association is fairly effective in spite of the strong
competition by the Et-Et H-bond association. It should be noticed that the cyH-cyH
affinity is generally stronger than the THF-THF attraction in spite of the lack in
cyH of polar functional groups; evidently, this tendency to association, as well as the
strong Et-cyH nonaffinity, are the passive result of the Et-Et and Et-THF associations.
The system MEt+THF+cyH behaves qualitatively as system I, as can be seen by
comparing the corresponding Δ
G
ij
between the two systems. However, Δ
G
11
is about
80% larger, and correspondingly Δ
G
33
and Δ
G
13
are also much larger in magnitude.
