Article
Samiey and Zafari
ethanol-water binary mixtures17 respectively.
Table 2. n, k1 , k-1 , k2 and Ea(k1) values of MG+ fading
reaction in various water-ethanol-1-propanol ternary
mixtures in constant concentrations of 1-propanol
obtained from SESMORTAC model at 283-303 K
As given in Table 2, in these ternary solutions: (a) At
each temperature, with increase in weight percentage of 1-
propanol, k1 values increase. (b) In each weight percentage
of 1-propanol, k2 values decrease with increase in tempera-
ture which is according to the trend of hydroxide ion nu-
cleophilic parameter, N+, values. (c) Fundamental rate con-
stants of reaction at each certain temperature change as
k2 >> k1 >> k-1.
T (K)
n
k1
k-1
k2
Ea (k1)
water-ethanol-1-propanol(5%)
283
293
303
1.502
1.600
1.610
8.30
15.07
29.41
2.31E-3
1.43E-3
7.43E-4
1.29E7
9.85E6
6.96E6
45.1
water-ethanol-1-propanol(10%)
283
293
303
1.982
1.674
1.679
4.92
15.42
29.89
4.00E-4
5.03E-4
2.82E-4
1.62E7
9.75E6
6.91E6
64.5
57.2
58.1
52.4
CONCLUSIONS
The rate constant of MG+ fading reaction increases in
ternary mixtures of water-ethanol-1-propanol. The results
show that in each certain temperature, rate constant of reac-
tion in ternary mixtures are greater than that of binary aque-
ous mixtures involving similar alcohol concentrations. The
fundamental rate constants of MG+ fading reaction in the
used ternary solvent systems are obtained by SESMORTAC
model. It was observed that at constant concentration of
one alcohol and variable concentrations of the second one,
with increase in temperature, k1 values increase and this in-
dicates that presence of ethanol (or 1-propanol) may in-
creases disssolution of 1-propanol (or ethanol) in ACSM.
At each temperature, due to increase in alcohol content of
ACSM, n values of the used ternary mixtures are less than
those of the related alcohol-water binary mixtures. Also, in
each certain zone and temperature, fundamental rate con-
stants of reaction change as k2 >> k1 >> k-1.
water-ethanol-1-propanol(15%)
283
293
303
1.796
1.722
1.627
9.65
21.93
48.07
1.81E-4
1.85E-4
1.98E-4
1.21E7
8.10E6
5.04E6
water-ethanol-1-propanol(20%)
283
293
303
1.853
1.527
1.607
12.94
39.46
65.66
5.64E3
2.58E-5
4.96E-6
1.06E7
5.61E6
1.01E5
water-ethanol-1-propanol(25%)
283
293
303
1.731
1.680
1.646
20.52
45.59
89.07
2.62E-4
2.82E-4
4.49E-5
8.50E6
4.46E6
7.35E5
MG+ fading reaction in water-ethanol-1-propanol(5%) is two-
zone which in the first zone, reaction rate is constant and para-
meters of the second region are given in Table 2. Ea(k1) values
are activation energy of k1 values. Dimensions of k1 and k-1
k2 and Ea(k1) are M-(n+1) min-1, M-n min-1, min-1 and kJ mol-1,
respectively.
,
placed by each other.
REFERENCES
It is found that in the used concentration range of eth-
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in 5 weight percentage of 1-propanol and two-zone in 10,
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¹
¹
S6-S10. As shown in Figs. 9 and 10, DS and DH values
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¹
¹
with more increase in ethanol concentration DS and DH
values become more negative and less positive, respec-
tively which has been explained before in the case of add-
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In each certain temperature, the observed rate con-
stant values of reaction in ternary mixtures are greater than
those of binary aqueous mixtures involving similar ethanol
concentrations, and n and k1 values of these ternary mix-
tures, Tables S6-S10, are less than and greater than those of
7. Pandit, N. K., Connors, K. A. J. Pharm. Sci. 1982, 71, 485.
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© 2012 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
J. Chin. Chem. Soc. 2012, 59, 32-39
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