Ethanol with Nitromethane and Diethylamine*

Home , Nitromethane

tions on experiments of Mr. Motoyoshi Hashitani (Tokyo Met- Literature cited ropolitan University, Dr. Course) 1) Belck, L.: Chem. Ingr. Techn., 23, 90 (1951) 2) Hashitani, M., M. Hirata, & Y. Hirose: Kagaku Kogaku Nomenclature {Chem. Eng. Japan), 32, 182 (1968) 3) Hala, E., et al. : "Vapour Liquid Equilibrium", Pergamon D = percentage deviation: Press (1958) = the value of 4) Johnson, A. L, & W. F. Furter: Can. J. Technol., 34, 413 log (71/V2) dxi (1957) where?i and j2 are activity coeff. 5) Landolt-Bornstein Zahlenwerte und Funktionen aus Physik. J a function of boiling points Chemie. Astronomic Geophysik und Technik 2. Teil b (1962) 6) Meranda, D. & W. F. Furter: Can. J. Technol., 44, 298 Tnim = the lowest measured temperature [°K] (1966) x\, xi = mole fractions of acetone & methanol in liquid phase, respectively (salt free basis) 7) Proszt, J. & G. Kollar: Roczen. Chem., 32, 611 (1958) yi, j/2 = mole fractions of acetone & methanol in vapor phase, 8) Timmermans, J. : "The Physico-Chemical Constants of Binary respectively (salt free basis) Systems in Concentrated Solutions" Interscience Pub. (1959) 9) Uchida, S., S. Ogawa, & M. Yamaguchi: Jap. Set. Rev. a = relative volatility of acetone to methanol Eng. Sci.y 1, 41 (1950) as = relative volatility salt free basis including salt 10) Yamamoto, Y. et al. : Kagaku Kikai {Chem. Eng. Japan), 0 = a function of boiling points 16, 166 (1952) ll) Yoshida, F. et al. : Kagaku Kogaku {Chem. Eng. Japan), = a function of log (7-1/7*2)

VAPOR-LIQUID EQUILIBRIA OF BINARY SYSTEMS CONTAINING ALCOHOLS : ETHANOL WITH NITROMETHANE AND DIETHYLAMINE*

KOICHIRO NAKANISHl*2 RITSUJI TOBA*3 AND HIDEKO SHIRAl*4 Department of Industrial Chemistry, Shinshu University, Wakasato, Nagano-shi

Vapor-liquid equilibrium data are reported for the binary systems ethanol-nitromethane (MeNO2) and ethanol-diethylamine (Et2NH) at 73OmmHg.As expected from a strong hydrogen-bond interaction between hydroxyl group and amino base, the ethanol-Et2NH system shows negative deviation from the idea! solution law and no azeotrope can be found. The ethano!-MeNO2 system shows a positive deviation. MeNO2forms an azeotrope at 76.4°C and 75.0 mole % of ethanol. Based on these results and other activity coefficient data available, the prediction of azeotrope3 formation in binary ethanol solutions by the previously presented correlation and azeotrope diagram is discussed.

In a series of studies on the vapor-liquid equilibria direction of the deviation from the ideal solution law, of binary solutions,^12'1" we have obtained the equi- is primarily dependent on the proton accepting ability librium data for ten binary methanol solutions. We of the molecule in alcohol solution. However, the have also proposed a correlation between the limiting value of the activity coefficient is also affected by the value of the activity coefficient of various liquids in difference in size and shape of component molecules. a large excess of methanol, log?"0, and the "hydrogen- It is thus necessary to obtain detailed information on bond shift" of the stretching vibration of the O-H such size effect for the purpose of establishing a gene- bond of methanol in these liquids, Jvs.12^ It was ralized activity coefficient correlation in alcoholic and demonstrated in these studies that the sign and magni- other associated solutions. Although a survey of the tude of the activity coefficient, i. e., the degree and literature indicates that, in contrast with binary methanol systems, both isobaric and isothermal vapor-liquid Received on April 30, 1968 equilibrium data are widely available for binary ethanol Presented in part at the 1st autumn meeting, the Society of Chemical Engineers, Japan, Toyonaka, Osaka, Nov. solutions, some important information as to the activity 1967 coefficient behavior in the ethanol systems is still To whomcorrespondence should be addressed to Depart- missing. ment of Industrial Chemistry, Kyoto University, Kyoto Present address : Hitachi Seisakusho Co. Ltd., Tokyo. In this paper, wewill report the barometric vapor- Present address: The Tokyo College of Pharmacy, liquid equilibrium data of ethanol (EtOH) with nitro- Shinjuku, Tokyo methane (MeNCh) and with diethylamine (Et2NH). 4 JOURNAL OF CHEMICAL ENGINEERING OF JAPAN Based on these data and other literature values, we Table 1 Physical properties of purified liquids will further discuss the comparison of the activity and the Antoine constants used coefficients of various organic liquids in ethanol with Ethanol Nitromethane Diethylamine those in methanol and the prediction of azeotropic be- Boiling point, havior in binary ethanol solutions. Obsd. 101.2 55.4 t, °C. Lit.a 78.4 101.2 55.5 Density , Materials d Obsd. 0. 78507 1. 1309 0.69893 Lit.a 0. 78508 1.1311 0.6926 The sample liquids used in this study were of the Refractive index, Obsd. 1. 3593 1.3267 1.3824 highest purity available. They were purified further nr>25 Lit.a 1.3595 1.3267 1.3783 in the following manner. Antoine constants81 MeNO2 and Et2NH were distilled several times A 8.21337 7. 26159 7. 14099 through a 30-plate column under nitrogen. The cri- B 1652.05 1436.38 1209.9 C 231.48 226. 670 229.0 terion for purified samples was the disappearance of a trace of impurity peaks on their gas chromatogram. Literature values are taken from (8, ll, 17). Silicone DC550 was used as column and EU as carrier Table II Vapor-liquid equilibrium data at 73OmmHg. gas. EtOH was purified by dehydrating with calcium Ethanol (l) -Nitromethane (2) oxide and by distilling through the same column as trcy r.2 0.030 0.157 97.7 2.564 0.972 for the other liquids. Although the gas chromatogram 0.047 0.223 93 2.707 1.045 indicates the presence of a trace of methanol in the 0.085 0.329 2.605 1.091 final distilled sample, physical constants such as density 0.122 0.395 86 2.420 1.126 and refractive index were in good agreement with 0.166 0.453 83.6 2.240 1.166 the accepted values. Since ethanol is highly hygro- 0.256 0.529 80.6 1.910 1.252 0.318 0.563 79.2 1.725 1.329 scopic, it was re-distilled immediately before use. 0.451 0.635 77.9 1.444 1.444 Table I lists some physical properties of the final 0.539 0.669 77.0 1.324 1.615 purified samples as well as the Antoine constants used 0.589 0.686 77.1 1.237 1.712 for vapor pressure calculation. 0.646 0.705 76.5 1.188 1.909 0.724 0.740 76.4 1.113 2.159 0.787 0.773 76.6 1.063 2.428 0.819 0.794 76.5 1.053 2.602 Experimental Procedure 0.859 0.822 76.7 1.033 2.870 0.914 0.871 76.9 1.019 3.383 The vapor-liquid equilibrium data were determined 0.953 0.930 77.7 1.011 3.263 on a modified Colburn still.6) The apparatus and 0.973 0.965 77.8 1.012 3.552 procedure were described in previous papers.9>15) The density data obtained by pycnometry and used Ethanol (l) -Diethylamine (2) t [°C]» 7i for the determination of mixture composition will be 0.029 56.9 0.851 1.006 published elsewhere. 0.049 57.9 0.814 1.005 0.073 59.2 0.831 1.002 0.125 61.8 0.843 0.989 Vapor-Liquid Equilibrium Data 0.149 62.8 0.833 0.993 å 0.175 64.0 0.830 0.985 Table II lists the vapor-liquid equilibrium data ob- 0.224 65.7 0.854 0.968 tained in this work. Although the mean pressure at 0.278 67.5 0.872 0.943 0.350 69.8 0.869 0.924 which the measurementsweremadewas 730mmHg*, 0.397 70.7 0.907 0.886 temperature was corrected to the normal boiling point 0.458 72.2 0.914 0.865 by the method described in a previous paper.15) 0. 608 74.7 0.953 0.781 The activity coefficients T were calculated by the 0.682 75.8 0.967 0.733 following equation. 0.727 76.3 0. 972 0.707 0.778 76.8 0.987 0.658 r=j~-expi(V-fi-(P-n)/RTl (1) 0.814 77.1 0. 994 0.629 0.912 78.0 0.994 0.569 The correction term due to the vapor phase imperfec- 0.962 78.0 1.001 0.567 tion was calculated by Wohl's generalized correlation.45 a corrected to 760mmHg. As the t-x-y diagrams in Figs. 1 and 2 illustrate, a minimum boiling azeotrope in the EtOH-MeNCh system occurs at 76.4°C and consists of 75.0 mole % D and J values were 16.92 and 10.37 for EtOH- of ethanol, while the EtOH-Et2NH system is non- MeNO2, and 3.22 and 10.55 for EtOH-Et2NH, respec- azeotropic. tively. Therefore the data for the EtOH-Et2NH The criterion for thermodynamic consistency given system are consistent. Those for the EtOH-MeNO2 by Herington5) was tested with the present data: the system are less satisfactory ; this is partly due to a the present x-y data can be regarded approximately as sharp decrease in boiling point in the region :rEtoH< those at 760mmHg. 0.25.

VOL.2 NO.1 1969 78.1 Fig. 3 Diagram of activity coefficients vs. composition

Fig. ! Vapor-liquid equilibrium diagram Table III Limiting activity coefficients for the EtOH-MeNO2 system System (log ft).ri-»o (log ft) X2^o EtOH (l)-MeNO2 (2) +0.50 +0.58 EtOH (l)-EtaNH (2) -0.07 -0.30

Table IV Limiting activity coefficient of various liquids in methanol and ethanol Limiting activity coefficient, log J° Liquid in MeOHa in EtOH Cyclohexane - +0. 85 (20) n-Heptane - +0.75 (7) w-Hexane - +0.90 (16) CCLi +0.85 +0.80 (18) Benzene +0.80 +1.00 (19) Nitromethane +0. 62 +0. 58 Ethyl acetate +0.43 +0.35 (3) Acetone +0.26 +0.25 (1) Acetic acid -0.20 -0.30 (14) Diethylamine -0. 44 -0. 30 a Cited from Table I in Ref. (12).

from the ideal solution law is observed for the EtOH- Et2NH system and that the EtOH-MeNO2 system

Fig. 2 Vapor-liquid equilibrium diagram shows a positive deviation. These results are similar for the EtOH-Et2NH system to these for the corresponding binaries containing methanol10|1U ; the sign of log/0 is the same, but its Since the activity coefficient of ethanol in Et2NH absolute values become smaller. For the EtOH-Et2NH takes a minimum, the Margules-type equation was used system, isothermal vapor-liquid equilibrium data are for correlation. It was found that the present data available which also show a negative deviation from can be correlated fairly well by the two-constant Mar- the ideal solution law.2) gules equation, In a previous paper,12) we have showna correlation between the log/0 of various liquids in excess of logU =x\{B +204 - B)xi~] J (2) methanol and the Avs in these liquids. It is interest- where the subscript 1 refers to ethanol. A set of the ing to investigate whether or not such a correlation Margules constants were evaluated from the data and exists also for ethanol solutions. Although the isobaric tabulated in Table III, and the experimental and cal- vapor-liquid equilibrium data are abundant for binary culated T values are plotted in Fig. 3. ethanol solutions, some of them are not accurate enough to evaluate log/0. Therefore we will show selected values of logT° evaluated from the literature. Limiting Activity Coefficient Correlation Table IV lists the log/0 values in ethanol and the The present data indicate that a negative deviation corresponding ones in methanol. It is to be remarked

JOURNAL OF CHEMICAL ENGINEERING OF JAPAN that the logf in ethanol is referred to 78.5°C, the a = constant in Eq. 3 normal boiling point of ethanol. If a comparison is D, J = parameters in the Herington equation K =constantinEq.3 made at 64.5°C, where those in methanol are referred to, it will have a slightly larger value than that given P = vapor pressure of pure liquid, mmHg R = gas constant in Table IV. Thus Table IV indicates that the limit- t - boiling point, °C ing activity coefficients of various liquids in ethanol T = temperature, °K are almost the same as those in methanol. As will T° =normal boiling point, °K be discussed in the succeeding paper,13) the change in V = molar volume the Avs value from one alcohol to another is minor. x = liquid phase composition, mole fraction y = vapor phase composition, mole fraction Consequently the logf0 vs. logAvs plots for methanol /3 = second virial coefficient and ethanol binaries will overlap with each other. y = activity coefficient Y° = limiting value of activity coefficient Azeotrope Prediction

Nomenclature 20)19) Wehe,Yuan, A.H.,K. S., Coates,Lu, B. J.:C.-Y.:A /. J. Ch.Chem.E.J., Eng.1, 241Data,(1955).8, 549 (1963). A, B = Margules constants 7

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