IUPAC-NIST Solubilities Database

IUPAC-NIST Solubility Database
NIST Standard Reference Database 106

Solubility System: 1-Propanol with heptane and Water

Components:
   (1) Water; H2O; [7732-18-5]  NIST Chemistry WebBook for detail
   (2) 1-Proponal (n-propanol, propyl alcohol, n-propyl alcohol); C3H8O; [71-23-8]  NIST Chemistry WebBook for detail
   (3) Heptane (n-heptane); C7H16; [142-82-5]  NIST Chemistry WebBook for detail

Evaluator:
   A. Skrzecz, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland (1997.03)

Critical Evaluation:

      A survey of reported compositions along the saturation curve (sat), and compositions of coexisting phases in equilibrium (eq.) for the system 1-propanol-tolene-water is given in Table 50.

Saturation curve    The ternary system 1-propanol-heptane-water forms a large miscibility gap of type 1 covering the majority of the concentration triangle The system was reported in the range 298-311 K and at the boiling point (vapor-liquid-liquid equilibria) at 101.3 kPa. Only the heptane-water binary system forms a miscibility gap. Data of this binary system were compiled and critically evaluated in a previously published SDS volume.⁶ The recommended mutual solubilities of the binary system heptane-water at 298.2 K⁶ are x"₂=4.3·10^–7 and x'₃=5.6·10^–4. The solubility of water in heptane reported by Ref. 2 is 0.0055 mole fraction (0.001 weight fraction), which differs from the recommended value by a factor of 10. This is the result of the method used by Vorobeva and Karapetyants.² The data sets at 298.2 K,^2,5 are consistent with each other, with the exception of the region close to the plait point (0.16<x₂<0.43); Letcher et al.⁵ present a slightly larger miscibility gap than Vorobeva and Karapetyants.² The temperature of 298.2 K, as a standard temperature in which various alcohol-hydrocarbon-water systems are presented, was chosen to present the behavior of this system. Saturation and equilibrium data of Refs. 2 and 5, were described by the equation: x₁=a₁·(–ln z₁)^{^a2}·z₁^{^a3}. where z₁=(x₂+0.5·x₁–x"₂₀)/(x'₂₀–x"₂₀), x'₁, x₂–mole fractions of component (1) and (2), respectively, x'₂₀, x"₂₀–values of x₂ on the binodal curve which cuts the x₁=0 axis.
   This equation has been proposed by Letcher et al., Ref. 7, for the description of saturation curves of ternary alcohol-ether-water systems. It gives better results (the smallest standard deviation) for the investigated system than any other tested equation. The parameters obtained by the least-squares method for the whole range of miscibility gap (water-rich and hydrocarbon-rich branches were described together) are: a₁=1.568 77, a₂=0.999 39, a₃=1.289 19. The standard error of estimate was 0.0138. Points for selected concentrations of heptane on the saturation curve were calculated by the proposed equation. These are presented in Table 51 and Figure 25 as calculated binodal curve (solid line). The maximum concentration of 1-propanol at this temperature is in the region of 0.470±0.025 (x₁=0.486, Ref. 5; x₁=0.448, calculated).
   Rabinovich and Pugachevich³ measured the system at 293.2 K as two phases in equilibrium. This data set presents a much larger miscibility gap particularly in hydrocarbon-rich phase; for a similar alcohol concentration (e.g. 0.390 mole fraction) the heptane concentration at saturation point differs from the value at 298.2 K² by about 0.130 mole fraction. The compositions of the water-rich phase at 293.2 K are in agreement with other data sets. McCants et al.¹ report saturation and equilibrium data at 310.9 K. At this temperature as was expected, data show a slightly smaller miscibility gap than those at 298.2 K. One point of the heptane-rich phase (x₁=0.1922 and x₂=0.7009) is an outlyer and presumably contains an experimental error. The paper of Timofeev, et al.⁴ presents equilibrium data at normal boiling points. The compositions of the heptane-rich phase are consistent with the results at 298.2 K, but the reported concentrations of heptane in the water-rich phase seem abnormal high (0.04–0.06 mole fraction); (heptane concentrations at 298.2 K were measured to be about 0.01 mole fraction and the temperature dependence is not expected to result such large changes).

Phases in equilibrium Compositions of coexisting phases in equilibrium for the ternary system 1-propanol-heptane-water were reported in all five references. The tie lines at 298.2 K (Refs. 2 and 5) are presented in Figure 25 . The distribution of 1-propanol between the phases changes slightly with the propanol concentration. This is observed in the data of Vorobeva and Karapetyants (Ref. 2) at 298.2 K. In the region x₁<0.24 the concentration of 1-propanol is slightly higher in the heptane-rich phase, while at higher alcohol concentrations, more 1-propanol is in the water-rich phase. Data of Letcher et al.⁵ confirm this behavior for the low propanol region (all three tie lines are located in this region). Other tie lines, reported at various temperatures, show similar direction as at 298.2 K with the exception of the results of McCants et al.¹ These tie lines are in nearly the opposite direction (the direction of the lines is consistent within this data set) than those presented in all other references. Plait points reported by Vorobeva and Karapetyants² at 298.2 K (x₁=0.4255 and x₂=0.3090) and Timofeev et al.⁴ at 349.4 K (x₁=0.43 and x₂=0.33) are very close to one another. All experimental tie lines as well as experimental points on saturation curve, Refs. 2 and 5, at 298.2 K, are shown in Figure 25 .

Experimental Data: (Notes on the Nomenclature)

TABLE 50. Summary of experimental data for the system 1-propanol-heptane-water
Author	T/K	DataType	Reference
McCants et al., 1953	311	sat. (15), eq. (4)	1
Vorobeva and Karapetyants, 1967	298	sat. (16), eq. (12)	2
Rabinovich and Pugachevich, 1974	293	eq. (5)	3
Timofeev et al., 1975	348,7-349.5	eq. (5)	4
Letcher et al., 1986	298	sat. (9), eq. (3)	5

TABLE 51. Calculated compositions along the saturation curve at 298.2 K
T/K	Mole Fraction x₁	Mole Fraction x₂
298.2	0.0000	0.000 000 43 Ref.6
298.2	0.2539	0.0200
298.2	0.3137	0.0400
298.2	0.3522	0.0600
298.2	0.3797	0.0800
298.2	0.4001	0.1000
298.2	0.4155	0.1200
298.2	0.4270	0.1400
298.2	0.4354	0.1600
298.2	0.4414	0.1800
298.2	0.4452	0.2000
298.2	0.4472	0.2200
298.2	0.4477	0.2400
298.2	0.4468	0.2600
298.2	0.4447	0.2800
298.2	0.4414	0.3000
298.2	0.4372	0.3200
298.2	0.4321	0.3400
298.2	0.4261	0.3600
298.2	0.4194	0.3800
298.2	0.4120	0.4000
298.2	0.4039	0.4200
298.2	0.3952	0.4400
298.2	0.3859	0.4600
298.2	0.3762	0.4800
298.2	0.3659	0.5000
298.2	0.3551	0.5200
298.2	0.3439	0.5400
298.2	0.3322	0.5600
298.2	0.3202	0.5800
298.2	0.3078	0.6000
298.2	0.2950	0.6200
298.2	0.2818	0.6400
298.2	0.2684	0.6600
298.2	0.2546	0.6800
298.2	0.2405	0.7000
298.2	0.2261	0.7200
298.2	0.2115	0.7400
298.2	0.1965	0.7600
298.2	0.1813	0.7800
298.2	0.1659	0.8000
298.2	0.1502	0.8200
298.2	0.1343	0.8400
298.2	0.1182	0.8600
298.2	0.1018	0.8800
298.2	0.0853	0.9000
298.2	0.0685	0.9200
298.2	0.0515	0.9400
298.2	0.0344	0.9600
298.2	0.0170	0.9800
298.2	0.0000	0.999 44 Ref. 6

View Figure 1 for this Evaluation

Notes:
Table 50  Number of experimental points in parentheses.

References: (Click a link to see its experimental data associated with the reference)

   1  McCants, J.F.; Jones, J.H.; Hopson, W.H., Ind. Eng. Chem. 1953, 45, 454-6.
   2  Vorobeva, A.I.; Karapetyants, M., Kh., Zh. Fiz. Khim. 41, 1144 (1967).
   3  Rabinovich, I.B.; Pugachevich, P.P., Zh. Fiz. Khim. 48, 2525 (1974).
   4  Timofeev, V.S.; Aristovich, V.Yu.; Sabylin, I.I.; Koshel'kov, V.A.; Pavlenko, T.G.; Serafimov, L. A., Izv. Vyssh, Uchebn. Zaved., Khim. Khim. Tekhnol. 18, 1219 (1975).
   5  Letcher, T.M.; Wootton, S.; Shuttleworth, B.; Heyward, C., J. Chem. Thermodyn 18, 1037 (1986).
   6  Shaw, D.G., ed., Solubility Data Series, Vol. 37, Hydrocarbons with Water and Seawater, Part I: Hydrocarbons C5 to C7 (Pergamon, New York, 1989).
   7  Letcher, T.M.; Ravindran, S.; Radloff, S.E., Fluid Phase Equilib, 69, 251 (1991).