IUPAC-NIST Solubility Database
NIST Standard Reference Database 106

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 Solubility System: Methanol with 2,2,4-Trimethylpentane (isooctane) and Water

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Components:
   (1) Water; H2O; [7732-18-5]  NIST Chemistry WebBook for detail
   (2) 2,2,4-Trimethylpentane (isooctane); C8H18; [540-84-1]  NIST Chemistry WebBook for detail
   (3) Methanol (methyl alcohol); CH4O; [67-56-1]  NIST Chemistry WebBook for detail

Original Measurements:
   Buchowski, H.; Teperek, J., Rocz. Chem. 33, 1093 (1959).

Variables:
   Temperature = 291 K - 293 K

Prepared By:
   A. Skrzecz

Experimental Data:   (Notes on the Nomenclature)
  

Compositions along the saturation curve

t/°C	T/K	Mass Fraction w1	Mass Fraction w2	Mole Fraction x1 (compiler)	Mole Fraction x2 (compiler)
18	291.2	0.670	0.330	0.8786	0.1214
18	291.2	0.760	0.233	0.9071	0.0780
18	291.2	0.787	0.198	0.9054	0.0639
18	291.2	0.801	0.177	0.9002	0.0558
18	291.2	0.823	0.145	0.8940	0.0442
18	291.2	0.841	0.118	0.8880	0.0350
18	291.2	0.846	0.072	0.8359	0.0200
18	291.2	0.800	0.029	0.7192	0.0073
18	291.2	0.744	0.003	0.6227	0.0007
18	291.2	0.540	0.002	0.3985	0.0004
18	291.2	0.441	0.001	0.3076	0.0002
20	293.2	0.662	0.338	0.8747	0.1253
20	293.2	0.763	0.224	0.8988	0.0740
20	293.2	0.789	0.190	0.8970	0.0606
20	293.2	0.823	0.136	0.8811	0.0408
20	293.2	0.838	0.089	0.8441	0.0251
20	293.2	0.829	0.051	0.7845	0.0135
20	293.2	0.781	0.023	0.6875	0.0057
20	293.2	0.617	0.003	0.4769	0.0007
20	293.2	0.545	0.002	0.4033	0.0004
20	293.2	0.493	0.001	0.3538	0.0002

Compositions of coexisting phases

t/°C	T/K	Mass Fraction w1	Mass Fraction w2	Mole Fraction x1 (compiler)	Mole Fraction x2 (compiler)	Comment(s)
18	291.2	0.057	0.943	0.1773	0.8227	hydrocarbon-rich phase
18	291.2	0.032	0.968	0.1054	0.8946	hydrocarbon-rich phase
18	291.2	0.048	0.952	0.1524	0.8476	hydrocarbon-rich phase
18	291.2	0.026	0.974	0.0869	0.9131	hydrocarbon-rich phase
18	291.2	0.024	0.976	0.0806	0.9194	hydrocarbon-rich phase
18	291.2	0.020	0.980	0.0678	0.9322	hydrocarbon-rich phase
18	291.2	0.013	0.987	0.0448	0.9552	hydrocarbon-rich phase
18	291.2	0.012	0.988	0.0415	0.9585	hydrocarbon-rich phase
18	291.2	0.000	1.000	0.0000	1.0000	hydrocarbon-rich phase
18	291.2	0.670	0.330	0.8786	0.1214	hydrocarbon-poor phase
18	291.2	0.772	0.215	0.9025	0.0705	hydrocarbon-poor phase
18	291.2	0.760	0.232	0.9055	0.0775	hydrocarbon-poor phase
18	291.2	0.812	0.166	0.9045	0.0519	hydrocarbon-poor phase
18	291.2	0.831	0.137	0.8971	0.0415	hydrocarbon-poor phase
18	291.2	0.841	0.117	0.8866	0.0346	hydrocarbon-poor phase
18	291.2	0.849	0.082	0.8535	0.0231	hydrocarbon-poor phase
18	291.2	0.847	0.071	0.8363	0.0197	hydrocarbon-poor phase
18	291.2	0.804	0.024	0.7200	0.0060	hydrocarbon-poor phase
20	293.2	0.050	0.950	0.1580	0.8420	hydrocarbon-rich phase
20	293.2	0.047	0.953	0.1495	0.8505	hydrocarbon-rich phase
20	293.2	0.036	0.964	0.1175	0.8825	hydrocarbon-rich phase
20	293.2	0.030	0.970	0.0993	0.9007	hydrocarbon-rich phase
20	293.2	0.025	0.975	0.0838	0.9162	hydrocarbon-rich phase
20	293.2	0.023	0.977	0.0774	0.9226	hydrocarbon-rich phase
20	293.2	0.017	0.983	0.0581	0.9419	hydrocarbon-rich phase
20	293.2	0.006	0.994	0.0211	0.9789	hydrocarbon-rich phase
20	293.2	0.000	1.000	0.0000	1.0000	hydrocarbon-rich phase
20	293.2	0.724	0.271	0.8950	0.0940	hydrocarbon-poor phase
20	293.2	0.733	0.260	0.8505	0.0891	hydrocarbon-poor phase
20	293.2	0.753	0.235	0.8961	0.0784	hydrocarbon-poor phase
20	293.2	0.781	0.201	0.8983	0.0649	hydrocarbon-poor phase
20	293.2	0.808	0.162	0.8910	0.0501	hydrocarbon-poor phase
20	293.2	0.818	0.145	0.8848	0.0440	hydrocarbon-poor phase
20	293.2	0.822	0.138	0.8821	0.0415	hydrocarbon-poor phase
20	293.2	0.840	0.084	0.8411	0.0236	hydrocarbon-poor phase
20	293.2	0.830	0.051	0.7860	0.0135	hydrocarbon-poor phase

Method/Apparatus/Procedure:
   Solubility was measured by the titration method. Known masses of methanol and water were titrated with 2,2,4-trimethylpentane until turbidity was observed. The mass of hydrocarbon was determined from mass balance of the mixture. To obtain equilibrium data, known masses of components were shaken and allowed to stand for over 2 h. Refractive indexes of the hydrocarbon-rich phase were measured and  phase composition was read from the calibration curve of the binary methanol-2,2,4-trimethylpentane mixture. Water concentration in the hydrocarbon-rich phase was neglected because the solubility of water in 2,2,4-trimethylpentane is lower than 0.000 05 mass fraction. Concentration of the water-rich phase was determined graphically from a large scale ternary diagram from the binodal curve, composition of hydrocarbon-rich and total composition of starting mixture.

Source and Purity of Materials:
   (1) F. O. Ch. Gilwice, pure grade; boiled with I₂ and Mg to remove water, distilled; middle fraction was used; n(20°C)=1.3288, p(20°C)=1.3914, p(20°C)=0.6920 g/cm³.
   (2) Obtained from the Physical Chemistry Department of Warsaw University, high purity grade; distilled only to remove water; n(20°C)=1.3914, p(20°C)=0.6920 g/cm³
   (3) Doubly distilled.

Estimated Errors:
   Solubility: Not reported.
   Temperature: Temp. ±0.5°C.

References:
   ¹ A. Weissberger, E. S. Proskauer, I. A. Riddick, and E. E. Toops, Organic Solvents, 2nd ed. (New York, 1995).

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Last updated: February 18, 2015 (Created: August 17, 2007)