1088
VERNONW. ARNOLDAND E. ROGERWASHBURN
extended t o thirty days under supercritical conditions, no a-quartz was formed. Acknowledgments.-The author wishes to acknowledge the help of Mr. Joseph Strauch who per-
Vol. 62
formed the chemical analysis and optical work, and of Dr. Warren 0. Groves and Mr. Ralph Ferguson of the Monsanto Chemical Company, Dayton, Ohio, for the X-ray patterns and their analysis.
TERNARY SYSTEM ISOAMYL ALCOHOL-ISOPROPYL ALCOHOLWATER AT 10, 85 AND 40' BY VERNONW. ARNOLDASD E. ROGERWASHBURN Department of Chemistru and Chemical Engineering, University of Nebraska, Lincoln, Nebraska Received April 88, 1968
Isopropyl alcohol is completely miscible with water and with isoamyl alcohol at ordinary temperatures while the latter two liquids have limited miscibility in each other. The ternary solubility curves and the distribution of isopropyl alcohol between the conjugate liquids have been determiued at 10, 25 and 40".
Introduction The solubility curves were determined by an extension of Alexejeff's method' as used for ternary systems by Jones and Grigsby.2 This method, in common use for binary solubilities, has the advantage that repeated observations may be made on the same sample. The temperatures, at which cloudiness indicated the appearance of a second liquid phase, were measured with a thermistor. The proportions of water in the less dense, or water poor, phases were determined by titration with Karl Fischer reagent as was done for some solutions by Purnell and Bowden. Experimental
pany, fitted with a ground glass connector was incorporated in one of the necks of the cell and was used as a resistance thermometer to determine the temperature of the contents of the cell. Measurements had been made of the resistances of the thermistor a t temperatures determined with a platinum resistance thermometer the constants of which had been determined by the Bureau of Standards. An equation of the type
was found to be suitable. The constant C, 323.5, was found by a selected point method. The constants A and B were then determined by the method of least squares to be 2091.2 and -2.7168, respectively. The final equation was used in the form
-
2091*2 323.5 log R 2.7168 The thermistor had a resistance of 3577 ohms a t 10" and 1086.5 ohms a t 40'. The cell containing the heterogeneous mixture of isoamyl alcohol and water was heated in a variable temperaIsopropyl alcohol was then ture water-bath, to about 45'. added until homogeneity resulted, and the amount of alcohol added was determined by weight. The mixture was fihaken mechanically in the bath while the temperature was lowered slowly until a uniform cloudiness throughout the mixture indicated the appearance of a second liquid phase. The temperature then 'was raised slowly until the cloudiness disappeared. This was repeated until temperatures corresponding to the appearance and disappearance of the secqnd liquid phase showed satisfactory agreement. The amount of isopropyl alcohol in the mixture then was increased by a small addition. The described procedure was repeated to determine the new temperatures corresponding to the appearance and disappearance of the second liquid phase TABLE I for the new concentrations. Five or moresuch pairs of conB.p. (cor.), OC. d'," n%= centration-temperature measurements were determined Isoamyl alcohol A 131.0 0.8051 1.4048 over the temperature range from 10 to 40" for each of fourIsoamyl alcohol B ... .8073 1.4052 teen different weight ratios of isoamyl alcohol to water. .4 curve, mean solution temperature u s . weight per cent. 82.2 .7809 1,3748 Isopropyl alcohol of isopropyl alcohol, was then plotted for each of the fourSolubility Curves.-The compositions of ternary solutions teen ratios. In determining the mean solution temperasaturated with respect to isoamyl alcohol or water or both ture, the temperature corresponding to the appearance of B of these materials were determined in the following manner. second liquid phaw was weighted twice as heavily as that Isoamyl alcohol and water, in a known ratio by weight, corresponding to its disappearance. The concentrations were placed in a specially prepared saturation cell. This of is0 ropy1 alcohol corresponding to 10, 25 and 40" were cell was made from a 50-ml. volumetric flask by the addition read g o m these curves. The concentrations of the other of B second glass stoppered neck to the bulb of the flask. two components were calculated from their weight ratios A thermistor, Type 14B from the Western Electric Com- and the concentration of isopropyl alcohol. These results are recorded in Table 11. The solubility of isoamyl alcohol in water was determined (1) M. W.Alexejeff, Bull. SOC. china.. 38, 145 (1882). by Alexejeff's method' using sealed tubes. The solubility of (2) H.E. Jones and W. E. Grigaby, Ind. EnQ. Chem., 44, 378 (1952). water in isoamyl alcohol was determined by analyzing satu(3) J. H. Purnell and S. T. Bowden. J . Chem. Soc., 539 (1954). rated solutions at each of the temperatures with Kar (4) J. Tirnmermans and E. Hennaot-Roland, Anal. soc. espan. ]Ea. Quim. 8 1 , 400 (laan). Fisc:hrr rengcnt.
Materials.-The isoamyl alcohol, 3-methyl-1-butanol, used in most of this work was prepared from isobutyl bromide by a met,hod similar to that described by Timmermans and Hennaut-Roland .4 Isobutylmagnesium bromide was allowed to react with paraformaldehyde. The resulting compound was hydrolyzed and the alcohol which was formed was purified until the constants recorded in Table I for sample A were obtained. Some distribution measurements were made a t 40' with isoamyl alcohol, 3-methyl-1-butanol, obtained from the Fisher Scientific Company. This material had the constants listed for sample B in Table I. The optical rotation indicated the presence of some of the optically active isomer 2-methyl-1-butanol. The isopropyl alcohol was obtained from the Eastman Kodak Company. After intensive drying with active calcium oxide, the alcohol was distilled yielding material having the constants recorded in Table I.
p =
+
TERNARY SYSTEMISOAMYL ALCOHOLISOPROPYL ALCOHOL-WATER
Sept., 1958
TABLE I1 SOLUBILITIES AT 10, 25 A N D 40' The Dlait Doints are indicated with asterisks.
-
Isoamyl alc., wt. %
-
Water, wt. %
Isopropyl alc., wt. %
loo
2.8 2.0 2.0 2.7 3.5 5.2 8.3 10.8 14.0 19.7 26.1 32.1 36.7 46.4 52.3 60.6 70.9 91.0 *14
97.2 95.1 88.6 78.3 75.8 71.4 65.6 61.1 55.7 46.7 38.1 31.9 28.2 22.2 19.7 16.4 13.5 9.0 *56
2.4 2.0 2.0 2.8 3.6 5.4 8.5 11.1 14.4 20.2 26.8 32.8 37.6 47.5 53.5 62.2 72.5 90.2 "14
25' 97.6 95.1 88.6 81.0 78.5 73.8 67.5 62.9 57 . 3 47.9 39.0 33.7 28.8 22.7 20.1 16.8 13.8 9.8 *58
0.0 2.9 9.4 19 .o 20.7 23.4 26.1 28.1 30.3 33.7 35.8 36.0 35.1 31.4 28.0 23.0 15.7 0.0
*30 0.0 2.9 9.4 16.2 18.0 20.!I 24.0 26.0 28.4 32.0 34.3 34.5 33.6 29.8 26.4 21.0 13.8 0 ,0 *28
40"
2.2 2.0 2.0 2.9 3.7 5.5 8.7 11.4 14.0 20.5
27.2 33.4 38.2 48.4 54.4 63.5 74.1 Y6.G '12
97.8
95.1 88.6 83.0 80.4 75.4 68.9 64.2 58.3 48.6 39.6 33.2 29.3 23.2 20.5 17.2 14.1 10.4 "63
0.0 2.0 9.4 14.1 16.0 19.1 22.4 24.5 27.I 30.9
23.3 33.4 32.5 28.4 25.1 19.3 11.8 0.0
*25
1089
The plait points were determined by means of large scale conjugation curves on triangular plots. The values agree with those obtained by the method of Treybal, Weber and Daley6within &2.0%. There is a region in the water-rich part of the phase diagram in which the compositions of the saturated ternary solutions do not vary a measurable amount with change in temperature from 10 to 40". The solubility curves for the three temperatures are almost indistinguishable in this region. Compositions between which the three solubility curves must pass were determined. Isoamyl alcohol was added slowly, with shaking, to mixtures of isopropyl alcohol and water. When the time required for the solution of one drop of isoamyl alcohol became great, the temperature was varied from less than 10' to more than 40' without any noticeable change in the appearance of the clear solution. This composition was recorded. Two drops of isoamyl alcohol then were added causing a slight cloudiness which persisted throughout the same temperature range. This composition was recorded. The difference in composition was of the order of a tenth of one per cent. Two such pairs of determinations were made. The means of the results of each pair of these determinations aye the identical compositions recorded in tBhesecond and third rows for each of the three temperatures in Table 11.
Distribution.-Mixtures of the three componeiits were prepared in such proportions by weight that two liquid layers were present at equilibrium. The mixtures were shaken in a constant temperature bath at the desired temperature until equilibrium was reached. The layers were theh allowed t o separate. Samples of the less dense, or water poor, layers were then removed and the proportions of water were determined by analysis with Karl Fischer reagent. The original gross compositions of the mixtures then were plotted on a large scale graph of the ternary solubility data. The water content of the less dense phase of each mixture was located on t,he solubility curve. Straight tie lines were then drawn through the corresponding gross compositions and solubilities of the phases of lower density. The proportions of the other components in the less dense layers and the conipositions of the more dense conjugate layers were then read from the intersections of the tie lines with solubility curves. Because of the larger proportions of water in the more dense layers, analysis for water with the Karl Fischer Reagent was not as accurate as by the graphical method. The tie line or distribution data are recorded in Table 111. "B" refers to Sample B of isoamyl alcohol listed in Table I. The analyses of the conjugate solutions containing isoamyl alcohol B were accomplished by the use of refractive index-composition curves. Discussion Ternary systems having the same pair of partly miscible liquids, isoamyl alcohol and water, but with methyl,6 ethyl6 and n-propyl' alcohols as the consolute liquid are represented with this system in Fig. 1. As would be expected, an increase in the length of the carbon chain of the consolute alcohol increases the proportion of the consolute alcohol in the less dense, or water poor, phase. The curve representing isopropyl alcohol lies between the curves for n-propyl and ethyl alcohols. The same order of increasing tendencies for these consolute alcohols to enter the less dense phase was noted in (5) R. E. Treybal, L. D. Weber and J. F. Daley, Ind. Eno. Chem, 38, 817 (1946). (6) F. Fontein, Z. phyeik. Chem., 78. 212 (1910). (7) J. Cod1 and H. B. Hoce THISJOURNAL, 39, 967 (193.5).
VERNONW. ARNOLD AND E. ROGER WASHBURN
Vol. 62
TABLE I11 COKCENTRATIONS-CONJUGATE LIQU~DB AT 10, 25 Gross composition Isoamyl alc., Water, wt. % wt. %
~.
__
W T % CONSOLUTE ALCOHOL I N THE MORE DENSE PHA
