J. Chem. Eng. Data lQ85, 30, 339-344
Vapor-Liquid Equilibria at 760 mmHg in the System Methanol-2-Propanol-Propyl Bromide and Its Binaries Jaime Wlsnlak' and Abraham Tamlr
Lbpartment of Chemical Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel 84 105
Vapor-llquid equilibrium at atmospheric pressure has been determined for the tltle ternary syslem and the blnarles d propyl bromlde with each alcohol. All system8 prewnl strong positive deviations from ideal behavior. The data were correlated by various equations, and the appropriate parameters are reported.
Table I. Physical Constants of Pure ComDounds refractive bp (760 purity index compd index at 20 O C mmHg), O C GLC (min) 1 methanol 1.3280" 64.68' 99.5 2-propanol
2
propyl bromide
3
The present work was undertaken as part of a project devoted to the determination of UNIFAC interaction parameters for bromine derivatives. There are only two publications in the literature on systems related to the ones reported here. Garber and Mironenko ( 7 ) studied the properties of azeotropes formed by propyl chloride with methanol. Lowering the pressure from 762 to 200 mmHg changed the boiling temperature of the azeotrope from 39.0 to 9.8 OC and its mole fraction composition from 0.743 to 0.813 (chloride). The system presented strong poslthre deviations from ideal behavior, and the data reported were found to be thermodynamically consistent according to the Herington (2) criterion but not consistent according to Rediich-Kister (3).Van Diemen et ai. ( 4 ) measured the excess enthalpies, excess Gibbs function, and excess volumes at 298.1 K for mixtures of 2-propanol with 2-bromopropane. They also reported vaporliquid equilibria data at 396 and 709 torr. Their resub indicated that the system presented positive deviations from Meal behavior and that a minimum Miing point azeotrope was present at a mole fraction of 2-bromopropane larger than 0.8. They interpreted their results on the excess properties as an indication that the interaction of an -OH group with a -CHBr group was of less importance than the interaction with a ketone group: alcohol associated complexes remained Intact to a greater extent with 2-bromopropane than in mixtures with acetone. Both publications report that compositions were determined by refractive index measurement. The data available on the system methanol-2-propanol have been thoroughly analyzed by Gmehiing and Onken (5). On the basis of thek analysis of the thermodynamic consistency of the different sets reported in the literature we have selected the data of Kohoutova et ai. (6) to complete the binary picture.
Experlmenlal Section Purffy of Maferlels. Analytical grade methanol and 2propanol (99 % +) were purchased from BDH. Propyl bromide (99.6%+) was supplied by Bromine Compounds Ltd., BeerSheva. The reagents were used without further puriflcation after gas chromatography failed to show any significant impurities. Properties of the pure components appear in Table I. npParetus and P". An allglass modlfied Dvorak and Boubiikova recirculation stili ( 8 ) was used in the equilibrium determination. The experimental features have been described in previous publications (9). Ail analyses were carried out by gas chromatography on a Packard-Becker Model 417 apparatus provided with a thermal conductMty detector and an Autolab Model 6300 electronic integrator. The cdumn was 20oCm long and 0.2 cm in diameter, was packed wlth Chromosorb 101 on
1.32&lb 1.3758' (25 1.3752b (25 1.4316'
OC)
"C)
1.4317b
64.70b 82.30" 82.50b 70.55'
99.5 99.4
7O.8Ob
Measured. Reference 7. Table 11. Experimental Vapor-Liquid Equilibria Data for Methanol (lkProw1 Bromide (3) at 760 mmHg temp, O C Xl Y1 71 YS 81.70 80.30 79.40 76.10 73.50 72.90 71.00 70.50 69.40 69.00 68.30 67.20 66.70 66.30
0.045 0.120 0.160 0.343 0.489 0.525 0.630 0.668 0.737 0.765 0.807 0.879 0.905 0.927
0.074 0.191 0.264 0.503 0.653 0.685 0.784 0.807 0.855 0.871 0.898 0.939 0.955 0.968
0.897 0.910 0.924 0.969 0.968 0.967 0.973 0.975 0.975 0.971 0.973 0.974 0.980 0.984
0.991 0.992 0.989 0.963 0.961 0.961 0.937 0.931 0.925 0.0936 0.928 0.924 0.886 0.833
80-100 mesh Supelcoport, and was operated isothermally at 150 OC. Injector and detector temperatures were 220 and 200 OC, respectively. Very good separation was achieved under these conditions, and calibration analyses were carried to convert the peak ratio to the weight composition of the sample. Concentration measurements were accurate to better than f 1% The accuracy in determination of pressure and temperature was AP = f 2 mmHg and At = 10.02 OC.
.
Results The temperature-"entration measurementsat 760 mmHg for the binaries and ternary systems are reported in Tables 11-IV and Figures 1 and 2. The activity coefficients were calculated from the following equations ( 10): in y, =
where
Vapor pressure PF was calculated according to Antoine's equation: (3) where the constants are reported in Table V. The virial coefficients B, and the mixed coefficient Buwere calculated by
002~-9560/05/1730-0339~0~.50/00 1985 American Chemical Sockty
340 Journal of Chemical and Englneerlng Data. Vol. 30, No. 3, 1985 i
Table 111. Experimental Vapor-Liquid Equilibria Data for 2-Propanol (2)-Propyl Bromide (3) at 760 mmHg tema O C 64.00 56.73 56.10 55.70 54.85 54.80 54.67 54.65 54.58 54.58 54.60 54.47 54.59 54.62 54.66 54.63 54.70 55.34 66.63 57.00 58.15 60.31 61.72 62.40 62.96 63.60
XO
0.020 0.090 0.135 0.195 0.260 0.285 0.350 0.365 0.405 0.485 0.515 0.550 0.575 0.590 0.610 0.615 0.630 0.735 0.780 0.880 0.915 0.950 0.965 0.978 0.985 0.990
Ye
Ye
YR
0.180 0.365 0.400 0.440 0.460 0.465 0.470 0.480 0.480 0.480 0.495 0.520 0.510 0.510 0.525 0.520 0.530 0.757 0.590 0.685 0.735 0.820 0.860 0.902 0.930 0.950
9.165 5.487 4.113 3.185 2.584 2.388 1.976 1.937 1.751 1.462 1.419 1.404 1.310 1.275 1.268 1.247 1.238 1.123 1.072 1.047 1.033 1.021 0.998 1.007 1.009 1.001
1.040 1.099 1.116 1.134 1.224 1.257 1.376 1.382 1.479 1.708 1.760 1.810 1.949 2.018 2.053 2.104 2.139 2.640 3.037 4.077 4.656 4.998 5.301 5.771 5.934 6.227
TOG
10'
'
012 ' 04 ' d.6
'
08 '
WE FRKTION 2-pRoPANoL-x,y Figm 2. Boiling point curve for 2-propanol (2)-propyl bromide (3)at 760 mmHg.
T"C '
0 2 ' 04 ' 06 ' 08 MXE FRACTION MEMAN~C-X,
'
lb
Flgure 3. Actlvity coefficients for methanol (1)-propyl bromide (3). iao- l
a!
02 '
04
a
06
d8 ' j0
MolE FRpxTi€)N METHANOL-x,y Flgure 1. Boiling point curve for methanol (1)-propyl bromide (3)at 760 mmHg.
the method of Tsonopoubs ( 7 7), using the molecular parameters suggested by the same author. For the binary systems the last two terms in eq 1 accounted for less than 5% of the activity coefficients; their influence was important only at dilute concentrations. The activity coefficients calculated according to eq 1 are reported in Tables 11-IV and Figures 3 and 4, and show that the binaries exhibit very strong positive deviations from ideal behavior and that both have a minimum boilng azeotrope. The azeotrope of the binary methanol-propyl bromide bolls at 54.6 OC and contalns 51.5% mole alcohol while that of 2propanol-propyl bromide boils at 66.6 OC and cntains 29% mole alcohol. The positive deviation from ideal behavior and presence of a minimum M n g point azeotrope is in accordance
'lo
02
a4
MXE FIICTKN
06
a8
io
2-pRoFRNM_-x2
Flgure 4. Activity coefficients for 2-propanol (2)-propyl bromMe (3).
with that of the other similar alkyl halide-alcohols systems reported above ( 7 , 4). The binary data appearlng In Tables I 1 and 111 were tested for thermodynamic consistency by the area and slope test as well as the Herington criteria (2). The consistency test parameters appear in Table V I and from it, it is concluded that the data are thermodynamically consistent.
Journal of Chemical and Engineedng Data, Voi. 30, No. 3, 1985 341
The ternary data reported in Table V were found to be thermodynamically consistent by the McDermot-Ellis method (72). According to this test, two experimental points a and b are thermodynamically consistent if the following condition is fulfilled: (4)
D
