The Journal of Physical Chemistry B
Article
Table 8. The Parameters of the Interstice Model for ILs, [Cnmim][ReO4], at 298.15 K
IL
10−24 v/cm3
∑v/ cm3
V/cm3.mol−1
102 ∑v/V
104α/K−1 (Cal)
104α/K−1 (Ex)
comparison of α/%
[C2mim][ReO4]
[C4mim][ReO4]
[C5mim][ReO4]
[C6mim][ ReO4]
16.48
18.91
20.33
21.29
19.85
22.77
24.47
25.64
167.4
198.2
217.8
232.6
11.85
11.49
11.23
11.02
5.97
5.78
5.65
5.55
5.43
5.80
5.98
6.03
−9.95
0.34
5.47
7.93
Kabo put forward a method of estimating vaporization heat
ASSOCIATED CONTENT
* Supporting Information
Additional details as described in the text. This information is
■
0
ΔlgHm (298 K) and interspace in ILs:
S
g
0
2/3 1/3
) + B
Δ H (298K) = A(γV
N
(20)
l
m
AUTHOR INFORMATION
Corresponding Author
Notes
In comparison, we can obtain
■
1/3
2/3
A = (36π) ε(l/2)
(21)
(22)
The authors declare no competing financial interest.
3
B = (P − P )(4/3)επr N
i
0
ACKNOWLEDGMENTS
■
where N is Avogadro's constant, and A and B are empirical
constants, A = 0.01121 and B = 2.4 kJ·mol−1.
The molar enthalpyies of vaporization for IL [Cnmim]-
This project was supported by NSFC (21003068, 21071073,
21101084, 21171080), the National Key Technology R&D Program
2012BAF03B02, the Education Bureau of Liaoning Province
(2009S041, 20111036) P. R. China, and Liaoning University
research funding.
[ReO4] calculated from eq 20 are listed in Table 7.
This table implies that the estimated enthalpy of vaporiza-
tion of ILs decreases with the length of aliphatic chains in the
1-alkyl-3-methylimidazoliun cation and it can be interpreted con-
sidering that longer side chains decrease the relative importance of
REFERENCES
■
(1) Wilkes, J. S.; Levisky, J. A.; Wilson, R. A.; Hussey, C. L. Inorg.
Chem. 1982, 21, 1263−1268.
(2) Robinson, J.; Osteryoung, R. A. J. Am. Chem. Soc. 1979, 101,
323−327.
(3) Robinson, J.; Bugle, R. C.; Chum, H. L.; Koran, D.; Osteryoung,
R. A. J. Am. Chem. Soc. 1979, 101, 3776−3779.
(4) Gale, R. J.; Osteryoung, R. A. Inorg. Chem. 1980, 19, 2240−2242.
(5) Endres, F. ChemPhysChem 2002, 3, 144−154.
(6) Wilkes, J. S.; Zaworotko, M. J. J. Chem. Soc., Chem. Commun.
1992, 965.
0
Coulomb forces leading to smaller values of ΔlgHm .
Rebelo et al.24 put forward a method of estimating the
hypothetical temperature of normal boiling point (NBP) of ILs,
Tb, in terms of critical temperature, Tc. They thought that the
relationship between Tb and Tc was Tb ≈ 0.6Tc for ILs. The
molar enthalpy of vaporization for the ILs at NBP, ΔlgHm0 (Tb),
can be estimated by the Trouton constant (≈ 90 J·mol−1·K−1).
0
According to Rebelo’s method, the predicted values of ΔlgHm
(Tb) of the ILs [Cnmim][ReO4] are also listed in Table 4.
(7) Dupont, J.; Souza, R. F.; de; Suarez, P. A. Z. Chem. Rev. 2002,
From Table 7, the difference between ΔlgHm0 (Tb) estimated
102, 3667−3692.
using Rebelo’s method and ΔlgHm (298 K) estimated using
0
(8) Zhou, M. D.; Zhao, J; Zang, S. L.; Fritz, K. E.; et al. Chem.Eur.
J. 2007, 13, 158−166.
Kabo’s method is very large. This is because of the heat capacity
difference between the liquid and gas phases at different tem-
peratures.22−25
(9) Zhou, M. D.; Yu, Y.; Zang, S. L.; Fritz, K. E.; et al. Chem.Asian
J. 2009, 4, 411−418.
(10) Yang, J. Z.; Jin, Y.; Xu, W. G.; Zhang, Q. G.; Zang, S. L. Fluid
Phase Equilib. 2005, 227, 41−46.
(11) Fang, D. W.; Tong, J.; Guan, W.; Wang, H.; Yang, J. Z. J. Phys.
Chem. B 2010, 114, 13808−13814.
4. CONCLUSION
In summary, a series of 1-alkyl-3-methylimidazolium perrhenate
ILs showing similar properties to conventional ILs are syn-
thesized and characterized. In terms of Glasser’s theory, the
standard molar entropy and lattice energy of the ILs are
calculated, respectively. Using Kabo’s method, the molar
(12) Tong, J.; Liu, Q. S.; Xu, W. G.; Fang, D. W.; Yang, J. Z. J. Phys.
Chem. B 2008, 112, 4381−4386.
(13) Fang, D. W.; Gu, X. J.; Xiong, Y.; Yue, S.; Li, J.; Zang, S. L.
J. Chem. Eng. Data 2010, 55, 4440−4443.
(14) Glasser, L. Thermochim. Acta 2004, 421, 87−93.
(15) Zaitsau, D. H.; Kabo, G. J.; Strechan, A. A.; Paulechka, Y. U.;
Tschersich, A.; Verevkin, S. P.; Heintz, A. J. Phys. Chem. A 2006, 110,
7303−7306.
0
enthalpy of vaporization of the IL, ΔlgHm (298 K), at 298 K
is estimated. As a new concept, the ion parachor is put forward
and applied to the ILs. The ionic volume and surface properties
of the ILs are estimated by extrapolation. The interstice model
is applied to calculate the thermal expansion coefficient of ILs
[Cnmim][ReO4] (n = 2,4,5,6), α, and the magnitude order of
its value calculated is the same as the experimental one. With
the interstice model, we have deduced the enthalpy of vaporiza-
tion equation, which is similar to Kabo’s method, and calcu-
lated the enthalpy of vaporization and vapor pressure of ILs
[Cnmim][ReO4] (n = 2,4,5,6) by the equation.
(16) Huddleston, J. G.; Visser, A. E.; Reichert, W. M.; Willauer,
H. D.; et al. Green Chem. 2001, 3, 156−164.
(17) Lide, D. R, Ed. Handbook of Chemistry and Physics, 82nd ed.;
CRC Press: Boca Raton, FL, 2001−2002.
(18) Deetlefs, M.; Seddon, K. R.; Shara, M. Phys. Chem. Chem. Phys.
2006, 8, 642−649.
(19) Knotts, T. A.; Wilding, W. V.; Oscarson, J. L.; Rowley, R. L.
J. Chem. Eng. Data 2001, 46, 1007−1012.
(20) Fang, D. W.; Guan, W.; Tong, J.; Wang, Z. W.; Yang, J. Z.
J. Phys. Chem. B 2008, 112 (25), 7499−7505.
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