Liquid–Liquid Equilibria for the Ternary Systems of FC3283 +

Article pubs.acs.org/jced

Liquid−Liquid Equilibria for the Ternary Systems of FC3283 + HFE7300 + Hexane, FC3283 + HFE7500 + Octane, and FC72 + HFE7100 + (Acetonitrile or Ethyl Acetate) at 273.15 K, 298.15 K, and 313.15 K Sang Young Lim,† Tae Gyu Lee,‡ Kwang Ho Song,†,‡,* and Jaehoon Choe§ †

Department of Chemical & Biological Engineering, Korea University, Seoul 136-713, Korea Green School, Korea University, Seoul 136-713, Korea § LG Chem Research Park, Daejeon 305-380, Korea ‡

S Supporting Information *

ABSTRACT: The temperature-induced phase behavior of a ternary system consisting of two fluorinated solvents and an organic solvent was studied. The solubility data and liquid− liquid equilibrium data for the following ternary systems were examined: (FC3283 + HFE7300 + hexane) at 273.15 K and 298.15 K, (FC3283 + HFE7500 + octane) at 298.15 K and 313.15 K, (FC72 + HFE7100 + acetonitrile) at 273.15 K and 298.15 K, and (FC72 + HFE7100 + ethyl acetate) at 273.15 K and 298.15 K. In addition, the experimental tie line data for eight ternary systems were correlated using the NRTL and UNIQUAC models, and the corresponding binary interaction parameters were determined. polar aprotic characteristics. It is also used with fluorinated solvents for applications such as the Mitsunobu reaction in an acetonitrile/HFE7100 biphasic system,5 radical carbonylations,6 and biphasic work-ups such as that using FC72 and acetonitrile.7 When perfluoroalkanes are used as the solvents, the lengths and large numbers of perfluoroalkyl groups on the catalysts are important factors to render the catalysts preferentially soluble in a fluorinated solvent phase to ensure the separation and recycling of the precious catalysts. To increase the separation efficiency, solvent tuning that uses hydrofluoroethers in conjunction with perfluoroalkanes may be required.8,9 Hydrofluoroethers consist of molecules with amphiphilic properties, where one part of the hydrofluoroether structure is a lipophilic alkyl group and the other part comprises a fluorophilic fluoroalkyl group that is used to tune the fluorophilicity of the fluorous phase.10−12 In this study, the respective liquid−liquid equilibria of (FC3283 + HFE7500 + octane) systems were studied at two temperatures, 298.15 K and 313.15 K. The liquid−liquid equilibria of the (FC3283 + HFE7300 + hexane) and the (FC72 + HFE7100 + acetonitrile or ethyl acetate) systems were also studied at 273.15 K and 298.15 K. Moreover, the

1. INTRODUCTION Phase-transition extraction can be induced by changing temperature or composition, and it shows higher stage efficiency compared with that of a standard extraction without a phase transition. In the standard extraction process, a stable and small-sized emulsion is required to increase the mass transfer surface area; however, a stable emulsion will be difficult to demulsify, so that a centrifuge is often required to perform the separation faster. For temperature-induced phase separation, many pairs of partially miscible liquids form a single phase during the heating stage, while during the cooling stage, the single-phase solution separates into two phases within a minute, and the desired solute is dissolved in the solvent phase. Organic solvents such as hexane and octane are used with perfluoroalkanes, which are saturated compound consisting solely of carbon and fluorine or also used with perfluamine, which is the common name for the organic compound whose IUPAC name is tris(heptafluoropropyl)amine. Some examples of reactions that use phase-transition extraction with fluorinated solvents are the Knoevenagel condensation of an aldehyde with a ketone in octane using perfluorinated solvent,1 the hydrogenation of 1-octene in an hexane/FC-75 biphasic system,2 and the oxidation of benzyl alcohol in hexane using a perfluorinated biphasic solvent system.3 The liquid−liquid equilibria for the ternary and quaternary system of (perfluorodecalin + hexane + heptane or hept-1-ene) were also reported.4 Acetonitrile is frequently used as a solvent for SN2 reactions because of its © 2014 American Chemical Society

Received: January 30, 2014 Accepted: April 22, 2014 Published: May 1, 2014 1656

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phase were withdrawn using syringes; the upper organic solvent-rich phase was withdrawn through a top injection port, and the lower fluorinated solvent-rich phase was withdrawn through the lower-side injection port. For phase sample analysis, an Agilent 6890N series gas chromatograph with an Agilent 7683 series automatic injector was used. A flame ionization detector was used to analyze the ternary systems. The gas chromatograph was operated with an Agilent Technologies HP-5 fused silica capillary column (30 m × 0.32 mm ID × 0.25 μm film thickness).

temperature-induced phase behavior of the ternary systems and their tie lines were studied. Various activity coefficient models such as the nonrandom two-liquid (NRTL) model13 and Universal Quasichemical (UNIQUAC) model14 were applied to correlate the tie lines.

2. EXPERIMENTAL SECTION The solvents used in this study were tris(heptafluoropropyl)amine (FC3283), perfluorohexane (FC72), HFE7100, HFE7300, HFE7500, hexane, octane, acetonitrile, and ethyl acetate. The purities and origins of the chemicals are listed in Table 1. Their chemical structures and boiling points were listed in Supporting Information, Table S1.

3. RESULTS AND DISCUSSION Liquid−liquid phase separation was studied using common inert nonpolar solvents such as hexane or octane and a

Table 1. Chemical Information chemical namea acetonitrile ethyl acetate hexane octane FC3283 FC72 HFE7100 HFE7300 HFE7500

source Acros Organics Carlo Erba Reagents Acros Organics Acros Organics 3M 3M 3M 3M 3M

initial mole fraction purity

purification method

analysis method

> 0.99

none

GCb

> 0.99

none

GCb

> 0.99

none

GCb

> 0.99

none

GCb

0.98 0.98 0.99 0.99 0.99

none none none none none

GCb GCb GCb GCb GCb

a

The IUPAC name: acetonitrile = acetonitrile; ethyl acetate = ethyl acetate; hexane = hexane; octane = octane; FC3283 = 1,1,2,2,3,3,3heptafluoro-N,N-bis(1,1,2,2,3,3,3-heptafluoropropyl)propan-1-amine; FC72 = 1,1,1,2,2,3,3,4,4,5,5,6,6,6-tetradecafluorohexane; HFE7100 = 1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxy butane; HFE7300 = 1,1,1,2,2,3,4,5,5,5-decafluoro-4-methoxy-4-(trifluoromethyl)pentane; HFE7500 = 3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2(trifluoromethyl)hexane. bGas−liquid chromatography.

Figure 1. Ternary phase diagrams at 298.15 K: ●, (FC72 (1) + HFE7100 (2) + acetonitrile (3)) system; ○, (FC3283 (1) + HFE7500 (2) + octane (3)) system; ■, (FC72 (1) + HFE7100 (2) + ethyl acetate (3)) system; □, (FC3283 (1) + HFE7300 (2) + hexane (3)) system.

The temperature-induced phase behavior of the ternary system was studied using the cloud-point method. Mininert valve (VICI Precision Sampling, Baton Rouge, LA, USA) equipped syringes were filled with each chemical and weighed on a Mettler AB304S balance with a precision of 0.0001 g. Two chemicals were injected into a 10 mL glass cell through a Mininert screw top, and the syringe was weighed again to determine the mass of the chemical that had been injected. The third chemical was then injected by mass on a Mettler AB304S balance to the 10 mL glass cell through the Mininert screw top until the first droplets of the second phase appeared, and the clear liquid became cloudy at a given temperature. The compositional points of the ternary mixtures at their respective cloud points were measured at 273.15 K, 298.15 K, and 313.15 K. The jacket of the 10 mL glass cell was connected to a cooling/heating circulator, whose temperature was controlled within ± 0.05 K. A 20 mL jacketed glass cell with a magnetic stirrer was used as the equilibrium cell for the experiments. Chemicals were injected into the 20 mL jacketed cell through the Mininert screw top, and the temperature of the ternary mixture was controlled using a cooling/heating circulator. The jacket temperature was controlled within ± 0.05 K. The feed mixture was stirred using a magnetic stirrer for 1 h to form an emulsion, and it was then allowed to settle for 6 h. Samples from each

Figure 2. LLE of FC3283 (1) + HFE7300 (2) + hexane (3) at 0.1 MPa: ○···○, Experimental tie line data and phase transition points at 273.15 K; □―□, experimental tie line data and phase transition points at 298.15 K.

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Figure 5. LLE of FC72 (1) + HFE7100 (2) + ethyl acetate (3) at 0.1 MPa: ○···○, experimental tie line data and phase transition points at 273.15 K; □―□, experimental tie line data and phase transition points at 298.15 K.

Figure 3. LLE of FC3283 (1) + HFE7500 (2) + octane (3) at 0.1 MPa: ○···○, experimental tie line data and phase transition points at 298.15 K; □―□, experimental tie line data and phase transition points at 313.15 K.

Table 2. Structure Parameters for the UNIQUAC Model chemicals

van der Waals volume, r

van der Waals area, q

acetonitrile ethyl acetate hexane octane FC3283 FC72 HFE7100 HFE7300 HFE7500

2.94 2.94 4.50 5.85 10.57 6.85 5.58 7.60 9.29

2.4 2.4 3.856 4.936 9.752 6.44 5.228 7.068 8.528

Table 3. Parameters of the NRTL and UNIQUAC Models for the FC (1) + HFE (2) + Organic (3) System and their RMSD Values at T/K = 298.15 Ka and P = 0.1 MPa bij/K

organic

Figure 4. LLE of FC72 (1) + HFE7100 (2) + acetonitrile (3) at 0.1 MPa: ○···○, experimental tie line data and phase transition points at 273.15 K; □―□, experimental tie line data and phase transition points at 298.15 K.

acetonitrile ethyl acetate

fluorinated solvent mixture of (FC3283 + HFE7300 or HFE7500). The ternary phase diagram of the (FC3283 + HFE7300 + hexane) system shows a smaller immiscibility region than that of the (FC3283 + HFE7500 + octane) system at 298.15 K as shown in Figure 1. The binary mixture data in Supporting Information, Table S2 show that hexane is more soluble in FC3283 than octane is. For the ternary system (FC3283 + HFE7300 + hexane), a homogeneous phase can be obtained at any liquid phase composition when the mole fraction of HFE7300 is more than ca. 0.15 K at 298.15 K. However, for the ternary system (FC3283 + HFE7500 + octane) at the same temperature, the homogeneous phase can be obtained at any liquid phase composition when the mole fraction of HFE7500 is at least 0.43. The results show that octane requires more HFE7500 to form a homogeneous phase. Acetonitrile and ethyl acetate are both polar aprotic solvents and have been tested with fluorinated solvents which have low boiling points such as FC72 and HFE7100 (Supporting

hexane octane

acetonitrile ethyl acetate hexane octane a

b12 b21 b12 b21 b12 b21 b12 b21 b12 b21 b12 b21 b12 b21 b12 b21

NRTL Model =837.0 b13 = 711.0 = −523.0 b31 = 1484.4 = −440.6 b13 = 189.9 = −472.0 b31 = 1007.2 = 463.6 b13 = 79.8 = −403.4 b31 = 907.7 = 640.6 b13 = 350.1 = −430.0 b31 = 934.6 UNIQUAC Model = −403.6 b13 = −495.7 = 258.4 b31 = −62.3 = −106.2 b13 = −186.7 = 250.6 b31 = −56.1 = −219.5 b13 = −201.5 = 183.9 b31 = 34.8 = −185.1 b13 = −189.5 = 148.4 b31 = 17.6

RMSD b23 b32 b23 b32 b23 b32 b23 b32

= = = = = = = =

−18.5 585.0 −336.2 −489.0 81.6 309.1 227.1 441.9

0.0043

b23 b32 b23 b32 b23 b32 b23 b32

= = = = = = = =

−121.3 −0.1 132.7 66.4 −15.8 −25.1 −69.8 −5.8

0.0064

0.0061 0.0055 0.0062

0.0058 0.0057 0.0124

Standard uncertainty for temperature was 0.05 K.

Information, Table S1). Acetonitrile is almost immiscible with a fluorocarbon solvent, FC72, and it has a large immiscible area with FC72 and HFE7100. However, ethyl acetate is partially 1658

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Table 4. Parameters of the NRTL and UNIQUAC Models for the FC (1) + HFE (2) + Organic (3) System and their RMSD Values at T/K = 273.15 or 313.15 Ka and P = 0.1 MPa model

bij/K

organic

RMSD

273.15 K NRTL

acetonitrile ethyl acetate hexane

UNIQUAC

acetonitrile ethyl acetate hexane

b12 b21 b12 b21 b12 b21 b12 b21 b12 b21 b12 b21

= = = = = = = = = = = =

698.7 −381.8 197.5 −395.1 842.4 −423.2 −299.7 186.4 98.6 −127.8 217.8 −396.9

b12 b21 b12 b21

= = = =

723.6 −495.6 256.0 −417.0

b13 b31 b13 b31 b13 b31 b13 b31 b13 b31 b13 b31

= = = = = = = = = = = =

719.9 1432.2 281.4 1028.4 212.3 956.8 −729.3 −98.3 −314.3 −17.7 −178.6 8.2

b23 b32 b23 b32 b23 b32 b23 b32 b23 b32 b23 b32

= = = = = = = = = = = =

19.6 680.3 −174.1 19.3 152.1 462.2 −308.8 1.1 50.1 −92.9 −184.8 46.6

0.0078

b13 b31 b13 b31

= = = =

350.1 880.2 −189.4 24.3

b23 b32 b23 b32

= = = =

339.4 306.6 −180.1 81.4

0.0061

0.0030 0.0064 0.0078 0.0018 0.0072

313.15 K

a

NRTL

octane

UNIQUAC

octane

0.0112

Standard uncertainty for temperature was 0.05 K.

miscible with FC72 and has a small immiscible area as shown in Figure 1. The temperature-induced phase behaviors and liquid−liquid equilibrium data of the ternary systems were studied using nonpolar organic solvents, hexane at 273.15 and 298.15 K (Figure 2, Supporting Information, Table S3) and octane at 298.15 K and 313.15 K (Figure 3 and Supporting Information, Table S4), and also using aprotic polar solvents, acetonitrile and ethyl acetate at 273.15 and 298.15 K (Figures 4 and 5, and Supporting Information, Tables S5, S6). The standard uncertainty, u(xi), which is equal to the square root of the estimated variance u2(xi), was calculated for the data based on the definition in the NIST report.15,16 In Figures 2 to 5, the region of the ternary phase diagram where the homogeneous phase region at higher temperature separates into two liquid phases at lower temperature is called the miscibility gap. The ternary phase diagram of the (FC3283 + HFE7300 + hexane) system has a large miscibility gap as it has a temperature difference of 25 K in Figure 2. The ternary phase diagrams of the (FC3283 + HFE7500 + octane) system in Figure 3 and the (FC72 + HFE7100 + acetonitrile) system in Figure 4 both have miscibility gaps with temperature differences of 15 K and 25 K, respectively. However, the ternary phase diagram of the (FC72 + HFE7100 + ethyl acetate) system in Figure 5 has a very narrow miscibility gap even for a temperature difference of 25 K. If fluorous catalytic reactions are performed in the miscibility gap region for a fluorous biphasic system as phase separation is increasingly promoted with decreasing temperature in this miscibility gap region, a product can be separated into the organic phase from the fluorinated solvent with fluorous catalysts. The ternary system (FC72 + HFE7100 + ethyl acetate) is not an optimal ternary system to use for fluorous liquid−liquid extraction because of its very narrow miscibility gap. NRTL and UNIQUAC models are the most commonly applied activity coefficient models. The NRTL and UNIQUAC models were used to correlate the experimental tie line data of ternary systems shown in Supporting Information, Figures S1− S8. The expression for the NRTL model is given by17

ln γi =

∑j xjτjiGji ∑k xkGki

+

∑ j

⎡ ∑ x τ G ⎤ ⎢τij − m m mj mj ⎥ ∑k xkGkj ⎥⎦ ∑k xkGkj ⎢⎣ xjGij

(1)

where Gij = exp(−αijτij), αij = αji, τii = 0, Gii = 1, τij = Δgij/RT = b ij /T, and R is the gas constant. In this work, the nonrandomness parameter, αij, was set to 0.3. The expression for the UNIQUAC model is given by17 ln γi = li −

Vi xi

∑ xjlj + ln j

⎛ + qi⎜⎜1 − ⎝

∑ j

Vi F + 5qi ln i xi Vi

⎞ − ln ∑ Fjτji⎟⎟ ∑k Fkτkj j ⎠ Fjτij

(2)

where Vi = ri/Σ ri xi, Fi = qi/Σ qi xi, li = z(ri − qi)/2 + (1 − ri), τij = Δuij/RT = bij/T and R is the gas constant. The respective van der Waals volumes, ri, and surface areas, qi, of the pure chemicals with their binary interaction parameters are listed in Table 2, and these were estimated using the Bondi group contribution method.18 The interaction parameters, bij and bji, are expressed in units of Kelvin and were regressed using the Aspen Plus process simulator (Aspen Technology Inc.). Comparison of the results is expressed by the root-mean-square deviation (σ) between the experimental and calculated compositions: N

σ=

2

3

exp cal 2 ∑k ∑ j ∑i (xijk − xijk )

6N

(3)

Here, N is the number of tie lines, and the subscripts i, j, and k are the indices for the components, phases, and tie lines, respectively. In addition, xexp is the experimental mole fraction, and xcal is the mole fraction calculated using the NRTL or UNIQUAC model. The root-mean-square deviation values in Tables 3 and 4 confirm that the respective data obtained from the NRTL and UNIQUAC models are in good agreement with the experimental data (Supporting Information, Figures S1− S8). 1659

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(5) Curran, D. P.; Bajpai, R.; Sanger, E. Purification of fluorous mitsunobu reactions by liquid−liquid extraction. Adv. Synth. Catal. 2006, 348, 1621−1624. (6) Ryu, I.; Niguma, T.; Minakata, S.; Komatsu, M.; Luo, Z. Y.; Curran, D. P. Radical carbonylations with fluorous allyltin reagents. Tetrahedron Lett. 1999, 40, 2367−2370. (7) Palomo, C.; Aizpurua, J. M.; Loinaz, I.; Fernandez-Berridi, M. J.; Irusta, L. Scavenging of fluorinated N,N′-dialkylureas by hydrogen binding: A novel separation method for fluorous synthesis. Org. Lett. 2001, 3, 2361−2364. (8) Yu, M. S.; Curran, D. P.; Nagashima, T. Increasing fluorous partition coefficients by solvent tuning. Org. Lett. 2005, 7, 3677−3680. (9) Chu, Q.; Yu, M. S.; Curran, D. P. New fluorous/organic biphasic systems achieved by solvent tuning. Tetrahedron 2007, 63, 9890−9895. (10) Eum, K. W.; Gu, H.; Lee, T. G.; Choe, J.; Lee, K.; Song, K. H. Liquid−liquid equilibria for the ternary systems of perfluorohexane + methyl nonafluorobutyl ether + toluene, + 1,4-dioxane, or + dimethylformamide at 298.15 K. J. Chem. Eng. Data 2013, 58, 915− 919. (11) Lee, T. G.; Kim, S. Y.; Choe, J.; Song, K. H.; Kim, J. H. Liquid− liquid equilibria for the ternary systems of perfluorohexane or perfluamine + hydrofluoroether + tetrahydrofuran at 298.15 K or 273.15 K. J. Chem. Eng. Data 2013, 58, 2035−2043. (12) Lee, T. G.; Song, K. H.; Choe, J. Liquid−liquid equilibria for the ternary systems of perfluamine + hydrofluoroether + benzene, toluene, or xylene at 298.15 K or 313.15 K. J. Chem. Eng. Data 2013, 58, 3130− 3136. (13) Renon, H.; Prausnitz, J. M. Local compositions in thermodynamic excess function for liquid mixture. AIChE J. 1968, 14, 135−144. (14) Abrams, D. S.; Prausnitz, J. M. Statistical thermodynamics of liquid mixtures: A new expression for the excess gibbs energy of partly or completely miscible systems. AIChE J. 1975, 21, 116−128. (15) Evaluation of measurement dataGuide to the Expression of Uncertainty in Measurement [Online]; JCGM 100:2008, GUM 1995 with minor corrections; Joint Committee for guides in Metrology: Paris, 2008; http://www.bipm.org/utils/common/documents/jcgm/ JCGM_100_2008_E.pdf (accessed Jan 29, 2014). (16) Taylor, B. N.; Kuyatt, C. E. Guidelines for evaluating and expressing the uncertainty of NIST measurement results; NIST Technical Note 1297; National Institute of Standards and Technology: Gaithersburg, MD, 1994. (17) Prausnitz, J. M.; Lichtenthaler, R. N.; Azevedo, E. G. d. In Molecular Thermodynamics of Fluid- Phase Equilibria, 3rd ed.; PrenticeHall PTR: Upper Saddle River, NJ, 1999; pp 290−292. (18) Bondi, A. Physical Properties of Molecular Crystals, Liquids & Glasses; Wiley: New York, 1968.

4. CONCLUSION Phase transition extraction has been conducted in the miscibility gap region. The temperature-induced phase behaviors of the fluorinated solvents with inert nonpolar solvents such as hexane or octane were studied. The ternary system (FC3283 + HFE7300 + hexane) was studied at two temperatures, 273.15 K and 298.15 K, and showed a larger miscibility gap for a small fraction of HFE7300. The ternary system (FC3283 + HFE7500 + octane) was studied at 298.15 K and 313.15 K and the equilibrium compositions of the components were measured. The temperature-dependent miscibility data of the fluorinated solvents in combination with polar aprotic solvents such as acetonitrile and ethyl acetate at two temperatures, 273.15 K and 298.15 K, were also investigated. For the ternary system (FC72 + HFE7100 + acetonitrile), the immiscibility gap was found to increase with decreasing temperature. However, the ternary system (FC72 + HFE7100 + ethyl acetate) was much less sensitive to temperature changes and formed a narrow miscibility gap. Therefore, in FC72 + ethyl acetate system, the choice of HFE7100 as a second solvent is not recommended since the ternary composition range for the phase transition was limited. Other ternary systems showed a large miscibility gap where the phase transition takes place. The experimental tie line data were correlated using the NRTL and UNIQUAC models, and the corresponding binary interaction parameters were determined.

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ASSOCIATED CONTENT

* Supporting Information S

Tables S1 to S6 and Figures S1 to S8 as described in the text. This material is available free of charge via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*Tel.: +82-2-3290-3307. Fax: +82-2-926-6102. E-mail: [email protected]. Funding

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF2012R1A1A2044286). Notes

The authors declare no competing financial interest.

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REFERENCES

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