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INDUSTRIAL AND ENGINEERING CHEMISTRY
reported here. The values of Hickman, Hecker, and Embree and of Ratchford and Rehberg are indicated in Figure 4 along with the present values. Excellent agreement is obtained between the values reported here and those of Ratchford and Rehberg a t higher temperature, the values coinciding a t 220' C. Dicapryl phthalate decomposed very rapidly in the tensimeter. Hence, only the results obtained in the dew-point apparatus are reported. Diiso-octyl phthalate is a mixture of phthalate esters made from alcohol mixtures containing small amounts of seven- and nine-carbon alcohols, in addition to eight-carbon alcohols. Hence, any method of determining vapor pressures is subject to error because of possible fractionation. Thus, in the dew-point method, the vapor pressure equilibrium is established betxeen the condensate and a vapor composition equal to that of the original samplr. Hence, results may be lower than values determined by a static method by an amount depending on the vapor pressures and mole fractions of the constituents of the sample. I n the tensimeter method, low values would again be obtained, but the effect mould be smaller since only a small fraction of the
Vol. 44, No. 11
sample is volatilized. This discrepancy would be significant only for materials having a wide distillation range. LITERATURE CITED
(1) Burrows, G., J . SOC.Chem. I n d . ( L o n d o n ) , 6 5 , 360 (1946). (2) Gardner, G. S., and Brewer, J. E., IND.EXG. CHEM., 29, 179 11937). (3) Hihkman, K. C . D., Hecker, J. C.. a n d Embree, N. D., IND. ~ N G . CHEX, ANAL. ED.,9, 264 (1937). (4) Kapff, S. F., a n d Jacobs, R. B., Re%.Sei. I n s t r u m e n t s , 18, 581 (1947). (5) Puck, T. T., and Wise, H., J . P h y s . Chem., 50, 329 (1946). (6) Ratchford, IT*. P., and Rehberg, C. E., A n a l . Chem., 21, 1417 (1949). (7) Schicktane, S. T., J . Research .\'atZ. Bur. Standards, 14, 685 (1935). ( 8 ) Small, P. A , , Small, K . W., and Cowley, P., T r a n s . Faraday Soc., 44, 810 (1948). (9) Verhoek, F. H., and JIarshall, A. L., J . Am. Chem. Soc., 61, 2737 (1939). RECEIVED for review July 14, 1951. ACCEPTED J u n e 5 , 1952. Presented before the Fourth ~Ieetinp;-in-hliniature, Philadelphia Section, . ~ X E R I C A N CHEMICAL SOCIETY, Philadelphia, Pa., Jan. 18, 1951.
ration of J
ALLEN S. SMITH AND JOHN F. LABONTEI University of Notre Dame, Notre Dame, I n d .
M
development. 2-Methyl furan was apparently available iri ETHYL ethyl ketone is a common solvent in cloth-coating Russia in 1940 where it was obtained from a fraction of a operations. It is vaporized into an air stream in thecourse xvood distillate. Some properties of the compound were pubof the operation and recovered from the mixture by absorption in lished a t that time, including the statement that it does not water. The aqueous solution is stripped to obtain an azeotropic form azeotropes with methyl acetate, methyl ethyl ketone, or mixture from which anhydrous methyl ethyl ketone can be obpropionaldehyde ( I S ) . Other entrainers n ith known desirable tained a t normal pressure only by the addition of some third comphysical properties are isopropyl formate and 1-chloro-2-methylponent. The azeotrope cannot be resolved into its components propane. These compounds are nonazeotropic with methyl ethyl by phase separation and fractionation, as is possible with the 12butyl alcohol azeotrope for example, because of a n abnormal soluketone and, like 2-methyl furan, are azeotropic Tvith Tvater. The behavior of ternary mixtures of the possible entrainers was unbility-temperature relation. This characteristic has been disknown. The use of 2-methyl furan as a nonselective entrainer cussed recently by Newman et al. ( I S ) . They reviewed methods for the dehydration of aqueous ethyl, isopropyl, and butyl alcowhich have been suggested for breaking the azeotrope and prohols is claimed in a recent patent (4). posed the use of butyl cellosolve in extractive distillation. A liqIndustrial dehydration processes use sodium or calcium chloiide uid-liquid extraction operation with a chlorinated hydrocarbon as the third component. Justification for the use of a different was suggested for recovery of methyl ethyl ketone from a dilute aqueous solution. A method method would be based on not included in the review emthr elimination of corrosion probploys a 40% caustic solution to lems and on improved economy dehydrate the azeotrope (8). of operation. This paper pre80 Pressure distillation to effect a sents physical data on 2-methyl change in the composition of the furan mixtures with water and 0' azeotrope has been patented remethyl ethyl ketone. The data cently (9). 70 x w e obtained to evaluate a 2 The possibility of using 2process in which aqueous methyl + methyl furan as a selective enethyl ketone is concentrated by dw trainer for water in the methyl n extraction using 2-methyl furan ethyl ketone azeotrope was in260 W which then serves as a selective + vestigated several years ago. entrainer to remove residual Physical data on the system vater by azeotropic distillation. were subsequently obtained 50 The data include solubility and when this compound became 0 10 20 30 40 50 60 7 3 80 90 100 equilibrium in the system 2c o m m e r c i a 11y a v a i l a b 1e for WEIGHT % DISTILLED methyl f u r a n - w a t e r - m e t h y i Distillation Curve of Methyl Ethyl Figure 1. 1 Present address, E. I. du Pont de ethyl ketone, and vapor-liquid Ketone-%-Methyl Furan-Water a t 747 M m . Nemours & Co., Inc., Cleveland, Ohio.
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INDUSTRIAL AND ENGINEERING CHEMISTRY
2141
equilibria in the systems of 2-methyl furan-water and 2-methyl furan-methyl ethyl ketone.
2-methyl furan and methyl ethyl ketone with water to obtain a cloud point. These data, given in Table I and plotted in Figure 2, were extended and checked by titrating mixtures of water and TERNARY DISTILLATION 2-methyl furan to miscibility with methyl ethyl ketone. A variation between the two methods was particularly noticeable a t high Preliminary work was carried out with 2-methyl furan prepared methyl ethyl ketone concentrations !vhere differences of 2 % of this by dehydration of furfural alcohol Over alumina at 3900 c. (14). component persisted. Further work was done with samples of the stabilized compound Tie lines for ternary system were obtained a t 25' C. by weighing supplied gratis by E. I. du Pont de Nemours & Co. This comphases separated a t equilibrium from known mixtures and applypound and technical methyl ethyl ketone were purified by fracing the lever arm principle. The method of Bancroft and Hubard tionation in packed columns, and heart cuts were taken a t con(a) was tried but was not applicable to the system. A correlastant temperature. Physical properties of the fractions retained tion of the equilibrium data was obtained by plotting the methyl for use, given in the following table, indicated satisfactory purethyl ketone concentration in one phase against the ratio of conity. Although the Zmethyl furan fraction, presumably without centration in both phases on logarithmic coordinates as shown in the stabilizer, developed color on standing in the dark before use, Figure 3. The molecular distribution equation is K = 17.32 no change in its physical properties could be detected. a / C i = 0.57, in which Cz and CI are the conMethyl Ethyl Ketone centrations of methyl ethyl ketone in the aqueous 2-Methyl Furan Exptl. literature Exptl. literature and organic phases, respectively, in weight per Boiling point at 760 mm., C. 63.6 6 3 . 7 (16) 79 806 6 79 57 805(16) (16) cent (18). The constancy of this distribution conSpecific gravity, 20/4 0.915 0 . 9 1 5 (7) stant is shown in Table I with the equilibrium Refractive index. ngo 1.4323 1.4332 (16) ... ... Refractive index, nLo ... ... 1 3766 1.3762 (16) results. METHYL ETHYL KETONE
The distillation characteristics of a mixture of methyl ethyl ketone, 2-methyl furan, and water were determined by fractionation in a 10-mm. inside diameter column packed with 90 em. of '/*-inch glass helices, and adapted for taking off a heterogeneous distillate. Reflux was obtained from a partial condenser. A typical distillation curve is shown in Figure 1. Three plateaus are evident, corresponding to the 2-methyl furan-water azeotrope (boiling a t 58.2" C. a t 760 mm.) excess 2-methyl furan, and methyl ethyl ketone. This result indicated that no ternary azeotrope was formed; all the water and 2-methyl furan in the charge were eliminated in the first two fractions. The water content of the 2methyl furan azeotrope was estimated to be 4% by material balance from the distillation data. Although anhydrous methyl ethyl ketone could be produced in this way from the azeotrope, the large amount of entrainer required made i t desirable to investigate the possibility of concentrating the aqueous methyl ethyl ketone by a preliminary extraction with 2-methyl furan.
A
TERNARY SOLUBILITY AND EQUILIBRIUM
Binary solubility data were available for water with 2-methyl furan ( 7 ) and with methyl ethyl ketone (16). T h e ternary solubility isotherm was determined a t 25" C. by titrating mixtures of
TABLE I. SOLUBILITY AND EQUILIBRIUM I N SYSTEM %METHYL FURAN-WATER-METHYL ETHYL KETONE AT 25" C. Methyl Ethyl 2-Methyl Furan, Ketone, Wt. % Wt. % 25.3 87.5 0.0 86.6 83.2 72.2 61.0
53.7 47.0 32.2 0.0
Water, Wt. %
SOLUBILITY I~OTHERM 74.7 0.0 0.0 0.3 4.3 9.8 23.6 36.3 44.0 51.6 67.0 99.8
EQUILIBRIUM Wt. % Methyl Ethyl Ketone in Organic phase, CI Aqueous phase, CZ 16.8 0.2 32.7 1.2 50.0 4.0 58.0 6.4 69.9 12.0 SO. 1 18.4 25.3 87.5
12.5 99.7 9.1 7.0 4.2 2.7 2.3 1.4 0.8 0.2
Solubility Diagram of Methyl Ethyl Ketone2-Methyl Furan-Water at 25" C.
The selectivity of 2-methyl furan for methyl ethyl ketone indicated that aqueous methyl ethyl ketone could be concentrated from the azeotrope or from dilute solution by extraction, and anhydrous methyl ethyl ketone obtained by distillation of the extract in which the 2-methyl furan becomes a n entrainer for residual water. VAPOR-LIQUID EQUILIBRIUM
-+E'
17'32 CI 0.60 0.56 0.55 0.55 0.57 0.57 0.58
Figure 2.
%METHYL FURAN-WATER.An equilibrium still was used similar to that described by Colburn et al. (5) for partially miscible liquids. Stoppers used in the original design were eliminated, and minor modifications were made to facilitate all-glass construction. Water and 2-methyl furan were vaporized separately at controlled rates. The vapors were mixed and brought to equilibrium in the still as indicated by a variation in temperature of less than 0.2' C. Samples of liquid and condensed vapors were then withdrawn for analysis. This was accomplished by titrating a known weight of the two-component sample to miscibility with methyl ethyl ketone at 25" C. ( 1 7 ) . The composition of the sample was obtained graphically from a solubility isotherm for the ternary system.
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TABLE11. VAPOR-LIQUID EQCILIBRIA OF %METHYL FURAN-ITATER AT 740 &hi. C.
Temp.,
96.8 90.2 89.6 83.8 79.2 76.7 73.1 69.9
