Abstract
The excess molar enthalpies of 1-octene + dimethylcarbonate or diethylcarbonate or 1,2-propylcarbonate have been measured at two high temperatures 363.15 K and 413.15 K and for pressures varying from 18 to 20 bar with an isothermal flow-calorimeter. All these mixtures have exhibited positive HEm.
1-octene; dimethylcarbonate; diethylcarbonate; 1,2-propylcarbonate; experimental excess molar enthalpies
EXCESS MOLAR ENTHALPIES OF 1-OCTENE + DIMETHYLCARBONATE OR DIETHYLCARBONATE OR 1,2-PROPYLCARBONATE AT 363.15 K AND 413.15 K
M. A. KRÄHENBÜHL1, R. BOELTS2 and J. GMEHLING2
1 DPQ / FEQ / UNICAMP, C.P. 6066, 13081-970 Campinas, SP - Brazil
e-mail: mak@feq.unicamp.br
2 Universität Oldenburg, TC-FB9, Postfach 2503, 26111 - Oldenburg, Germany
e-mail: gmehling@tech.chem.uni-oldenburg.de
(Received: August 25, 1997; Accepted: November 2, 1997)
Abstract - The excess molar enthalpies of 1-octene + dimethylcarbonate or diethylcarbonate or 1,2-propylcarbonate have been measured at two high temperatures 363.15 K and 413.15 K and for pressures varying from 18 to 20 bar with an isothermal flow-calorimeter. All these mixtures have exhibited positive HEm.
Keywords: 1-octene, dimethylcarbonate, diethylcarbonate, 1,2-propylcarbonate, experimental excess molar enthalpies.
INTRODUCTION
Wallis et al. (1984) said that the excess molar enthalpy HEm is a particularly exacting test of predictions based on molecular theories of liquids. The HEm values can theoretically be derived from vapor-liquid equilibrium (VLE) results for mixtures, but a calorimetric determination of HEm is the preferred method.
Thermodynamic properties of carbonated hydrocarbon mixtures are poorly reported in the literature despite their great theoretical and technical interest. There is no HEm data for these systems in the literature.
In order to be able to interpret the chemical and physical properties of these mixtures, this work reports the experimental excess molar enthalpies of 1-octene + dimethylcarbonate or diethylcarbonate or 1,2-propylcarbonate at two different temperatures: 363.15 K and 413.15 K and pressures varying from 18 to 20 bar. The mixture of the 1-octene with the 1,2-propylcarbonate (ringered compound) shows a gap of miscibility, while the mixtures of the 1-octene with the other two non-ringered carbonated compounds have no gap of miscibility. The measured data were fitted to a Redlich-Kister series expansion.
EXPERIMENTAL
All materials were supplied by Aldrich (Germany). The purities of the chemicals were greater than 99%. The liquids were stored over
activated molecular sieve and were used directly without further purification. All the liquids were subjected to GC analysis and to water determination. The results are given in Table 1. Densities of liquids were measured at T = 298.15 K using an electronic densimeter (Anton-Paar: DM 020D) and agreed well with literature values that are given also in Table 1. The values used for the densities were corrected by a polynom according to the given pressure for each system that are presented in Table 3.
A Hart Scientific isothermal flow-calorimeter was used for the measurements of excess molar enthalpies. The calorimeter and the experimental technique have been described by Ott et al. (1986). The calorimetric measurements were carried out with a total flow rate of 1.11x10-2 cm3.s-1. The energy pulse of the calorimetric method was set as 1m J for the 1-octene + diethylcarbonate system and 2m J for the 1-octene + dimethylcarbonate or 1,2-propylcarbonate systems. The uncertainty in the determination of excess enthalpies HEm was estimated to be greater than ç0.02 . HEm ç.
RESULTS AND CONCLUSIONS
The values of HEm for the studied mixtures are listed in Table 2 and plotted in Figures 1 to 3 x . They are smoothed by least squares to a Redlich-Kister series expansion, defined by the equation:
(1)
The parameters of equation (1) together with the standard deviations of the fit are given in Table 3. The 
values that were calculated by means of the RK-Model are presented in Table 4 for all the mixtures at both temperatures. The HEm values obtained for the mixture 1-octene + 1,2 propylcarbonate show partial miscibility at the experimental temperatures, and in the region of total miscibility the HEm values are positive and large. This behaviour has been explained in terms of association through dipolar interactions, additional or alternative to hydrogen bonding by Franzen and Stephens (1963) and Tomas et al. (1992). The HEm values of 1-octene + non-ringered carbonated compounds mixtures decrease with an increasing number of methyl groups.
There is very little temperature dependence of HEm for 1-octene + dimethylcarbonate or diethylcarbonate under the two measured temperatures.
a Dymond et al. (1988); b Abas-Zade et al. (1971); c Aicart et al. (1995); d De La Fuente et al. (1992); e Francesconi and Comelli (1995a); f Francesconi and Comelli (1995b,c); g Moumouzias G. et al. (1991), h Muhuri and Hazra (1994);
i Francesconi and Comelli (1995d)
T = 363.15 K
T = 413.15 K
1-Octene / Dimethylcarbonate
1-Octene / Diethylcarbonate
1-Octene / 1,2 Propylcarbonate
x1
HE m / J.mol-1
x1
HE m / J.mol-1
x1
HE m / J.mol-1
0.0000
0
0.0000
0
0.0000
0
0.0138
104.280
0.0197
53.508
0.0136
104.280
0.0278
205.062
0.0396
103.755
0.0275
205.062
0.0570
426.813
0.0800
207.188
0.0564
426.813
0.0876
648.034
0.1213
301.776
0.0866
648.034
0.1197
835.604
0.1636
385.938
0.1185
835.604
0.1535
1019.467
0.2069
463.614
0.1519
1019.467
0.1890
1095.896
0.2512
529.409
0.1872
1095.896
0.2265
1057.356
0.2965
591.621
0.2245
1057.356
0.2661
1030.014
0.3428
641.767
0.2638
1030.014
0.3080
1001.374
0.3904
683.248
0.3055
1001.374
0.3523
993.005
0.4390
719.860
0.3496
993.005
0.3993
970.672
0.4889
733.067
0.3965
970.672
0.4493
956.931
0.5400
735.456
0.4464
956.931
0.5025
956.935
0.5924
723.644
0.4996
956.935
0.5593
968.701
0.6462
698.221
0.5564
968.701
0.6200
971.174
0.7013
647.436
0.6172
971.174
0.6851
982.068
0.7579
579.720
0.6825
982.068
0.7550
985.365
0.8160
467.854
0.7528
985.365
0.8304
1009.427
0.8757
331.784
0.8287
1009.427
0.9118
772.914
0.9370
164.150
0.9108
772.914
0.9550
419.411
0.9683
74.921
0.9545
419.411
1.0000
0
1.0000
0
1.0000
0
Figure 1: Molar excess enthalpies of 1-octene / dimethylcarbonate at 363.15 K (o )
and 413.15 K ( D ).
Figure 2: Molar excess enthalpies of 1-octene / diethylcarbonate
at 363.15 K (o ) and 413.15 K (D ).
Figure 3: Molar excess enthalpies of 1-octene / 1,2-propylcarbonate
at 363.15 K (o ) and 413.15 K (D ).
Parameters of the smoothing equations (1) for molar excess enthalpies and standard deviations s [ J.mol
T = 363.15 K
Mixture (1-Octene +)
P/bar
C0
C1
C2
C3
C4
C5
s
Dimethylcarbonate
19.62
5299.0
-116.05
-181.95
-384.76
8.45
Diethylcarbonate
19.27
2900.8
326.59
628.29
54.149
-686.42
-134.87
3.68
1,2-Propylcarbonate
18.93
no suitable fit found
T = 413.15 K
Mixture (1-Octene +)
P/bar
C0
C1
C2
C3
C4
C5
s
Dimethylcarbonate
18.24
5293.8
-166.17
-313.01
528.35
-359.09
-1151.2
7.46
Diethylcarbonate
20.31
2925.1
497.7
520.12
-707.58
-969.83
-
5.14
1,2-Propylcarbonate
17.55
no suitable fit found
ACKNOWLEDGEMENT
The authors are grateful to the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) and to the Deutscher Akademischer Austauschdienst (DAAD) for financial support of M.A.K.
- Abas-Zade, A. K.; Kerimov, A. M. and Apaev, T. A., Izv. Vyssh. Uchebn. Zaved. Neft Gaz, 2: 77, (1971)
- Aicart, E.; Junqueira, E. and Letcher, T. M., J. Chem. Eng. Data, 40 (6): 1225, (1995)
- De La Fuente, I. G.; Gonzalez, J. A. and Cobos, J. C., J. Chem. Eng. Data, 37 (4): 535, (1992)
- Dymond, J. H.; Malhotra, R.; Isdale, J. D. and Glen, N. F., J. Chem. Thermodyn, 20: 603, (1988)
- Francesconi, R. and Comelli, F., J. Chem. Eng. Data, 37 (4): 811, (1995a)
- Francesconi, R. and Comelli, F., Thermochim. Acta, 258 (1): 49, (1995b) and 260: 95, (1995c)
- Francesconi, R. and Comelli, F., J. Chem. Eng. Data, 40(1): 31, (1995d)
- Franzen, J. S. and Stephens, R. E., Biochemistry, 2: 1321, (1963)
- Moumouzias, G.; Panopoulos, D. K. and Ritzoulis, G., J. Chem. Eng. Data, 36 (1): 20, (1991)
- Muhuri, P. K. and Hazra, D. K., J. Chem. Eng. Data, 39 (2): 375, (1994)
- Ott, J. B.; Stouffer, C. E.; Cornett, G. V.; Wirthlin, R. C.; Christensen, J. J. and Deiters, U. K., J. Chem. Thermodynamics, 18: 1, (1986)
- Tomas, G.; Artal, M. and Otíns, S., J. Chem. Thermodynamics, 24: 1167, (1992)
- Wallis, K. P.; Clancy, P.; Zollweg, J. A. and Streett, W. B., J. Chem. Thermodynamics, 16: 811, (1984).
Publication Dates
-
Publication in this collection
09 Oct 1998 -
Date of issue
Mar 1998
History
-
Accepted
02 Nov 1997 -
Received
25 Aug 1997
