Phase Behavior of the Ternary System ... - ACS Publications

Article pubs.acs.org/jced

Phase Behavior of the Ternary System Acetylferrocene, The Ionic Liquid 1‑Butyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide, and Carbon Dioxide To Be Applied in Friedel−Crafts Acylation Reactions Somayeh Kazemi,† Cor J. Peters,†,‡ and Maaike C. Kroon*,† †

Department of Chemical Engineering and Chemistry, Separation Technology Group, Eindhoven University of Technology, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands ‡ Chemical Engineering Program, The Petroleum Institute, P.O. Box 2533, Abu Dhabi, United Arab Emirates ABSTRACT: To investigate the possibility of applying the miscibility switch phenomenon to perform Friedel−Crafts acylation reaction, the high-pressure phase behavior of the ternary system containing acetylferrocene, the ionic liquid 1-butyl-3methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][Tf2N]) and carbon dioxide (CO2) is studied experimentally. Acetylferrocene is the product of the acylation reaction of ferrocene and has applications as an intermediate in the production of functional groups, in polymers, as combustion catalysts for propellants, and in medical chemistry. The experiments are performed using a synthetic method in the Cailletet apparatus within a pressure range of 0.25 MPa up to 10 MPa and in a temperature range of 278 K up to 368 K. Five different concentrations of CO2 [(10, 20, 31, 40, and 50) mol % of CO2] were investigated. In a Cailletet apparatus, temperature (or pressure) is kept constant at preset values, and the pressure (or the temperature) is varied until a phase change is visually observed for a sample with a constant overall composition. Changing the preset temperature (or pressure) allows measuring another point of the same sample. The solute effect on the phase behavior is studied by comparing the experimental results of the binary system [bmim][Tf2N] + CO2, which were collected previously, with those of the ternary system ferrocene + [bmim][Tf2N] + CO2. It is shown that the addition of an acetyl group to the ferrocene molecule dramatically changes the phase behavior of the binary system. The homogeneous liquid phase region is also determined experimentally, for which data are used to study the acylation in this work. This study indicates that performing the acylation reaction of ferrocene to acetylferrocene in the presence of [bmim][Tf2N] and CO2 in the occurrence of a homogeneous liquid phase is feasible.

1. INTRODUCTION Friedel−Crafts acylation is an important reaction with increasing application in many fields such as material science, catalysis, bio-organometallic chemistry, and the pharmaceutical industry.1,2 One of the well-known examples is the acylation reaction of ferrocene to acetylferrocene. This reaction has been identified as playing a significant role in organometallic chemistry, materials science, and in asymmetric and electrocatalysis.3,4 The traditional method of acylation reactions makes use of toxic volatile organic compounds such as dichloromethane or carbon disulfide, resulting in environmental and human health risks.5 Moreover, corrosion issues and, depending on the Lewis acid used as the catalyst, considerable quantities of harmful waste can be dealt with. To rectify the shortcomings of conventional organic solvents, ionic liquids (ILs) have been introduced in chemical reactions as a solvent. ILs are salts consisting of an organic cation and an organic or inorganic anion which are generally liquid at room temperature. There © 2013 American Chemical Society

are several advantages of using ILs as solvents instead of conventional organic compounds, for example, no measurable vapor pressure at room temperature, low flammability, and high solvency power.6 Recently, a comprehensive investigation of the acylation of ferrocene into acetylferrocene has been conducted in the presence of ILs as a solvent instead of the conventional organic solvents.7 The promising results show that up to 100% conversion and yield could be reached using imidazoliumbased ILs, especially 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][Tf2N]) as a solvent with scandium triflate (Sc(OTf)3) as a catalyst (Figure 1). In spite of the mentioned advantages over IL application as reaction media, the following extraction stage normally uses organic solvents. As a result, even though one step of the Received: November 19, 2012 Accepted: February 20, 2013 Published: March 6, 2013 951

dx.doi.org/10.1021/je301241k | J. Chem. Eng. Data 2013, 58, 951−955

Journal of Chemical & Engineering Data

Article

reported on the ternary phase behavior of IL + CO2 + organic systems, where the organic compound is a solid.23,24 It is our intention in this work to measure the phase behavior of the ternary system containing the solid organometallic compound of acetylferrocene in the presence of IL [bmim][Tf2N] and CO2. Acetylferrocene is an intermediate in the production of functional groups in polymers, combustion catalysts for propellants, and in medical chemistry.2,25 Measurements are carried out at temperature range of 278 K to 368 K and pressures up to 10 MPa. To find optimum reaction and separation conditions, a comparison of the results from this study is made with the results from our previous study on phase behavior of the ternary system of ferrocene + [bmim][Tf2N] + CO2. Also to better understand the effect of addition of acetylferrocene to the binary system [bmim][Tf2N] + CO2, ternary data obtained in this work are compared to the phase behavior of the binary system [bmim][Tf2N] + CO2.

Figure 1. Friedel−Crafts acylation reaction of ferrocene to acetylferrocene.

process is being performed in more environmentally benign solvent, the whole process cannot be considered as environmentally friendly since it still suffers from the involvement of volatile organic solvents. Furthermore, it has been shown that supercritical carbon dioxide (scCO2) can be used to extract the product from the reaction mixture with ILs as a solvent.8 The reason is that the solubility of CO2 in ILs is generally very high, but CO2 is not able to dissolve most ILs.9 The straightforward spinoff of this finding is to extract an organic compound from an IL using scCO2 without any contamination by the IL.10 ScCO2, possessing a mild critical pressure (7.38 MPa) and temperature (304.25 K), has received much attention compared to other supercritical fluids because of their remarkable properties such as nonflammability and nontoxicity as well as low price and ease of recycling.11 Furthermore, it is possible to tune the solvency power of scCO2 by adjusting the pressure, which makes it a good candidate for the extraction processes. One of the interesting characteristics of CO2 in ternary systems (known as the miscibility switch phenomenon) is that it can force two immiscible liquid phases into one homogeneous phase.12 Based on this phenomenon, it is possible to combine reactions and separations in the presence of ILs and CO2, in which the reaction is performed in the homogeneous phase and after completion of the reaction, changing the conditions, resulting in a phase split in which one of the phases is substantially free of IL allowing the recovering of the product.13,14 To apply above-mentioned process concept, it is crucial to locate the homogeneous and heterogeneous region in the ternary systems containing reactants or products in the presence of ILs and CO2. Therefore, ternary phase behavior data are necessary to find the optimum reaction and separation conditions. Although there have been many studies conducted on the measurement of the binary phase behavior of systems containing ILs and CO2,13−16 studies on multicomponent systems containing ILs are still very limited. Fortunately, there is a steadily growing interest in investigations of the phase behavior of ternary systems containing ILs and CO2. A number of studies have been conducted to measure the phase behavior of ternary IL + CO2 + organics systems, where the organic compound is an alcohol, a ketone, or an ether, either liquid or solid at room temperature.17−24 Different types of phase transitions have been observed in the studied systems, of course, depending on the type of organic molecules, type of IL, and their concentrations.17−22 It also has been shown that the solutes with similar molecular structure can have different influences on the phase behavior of the ternary systems.20,24 Interestingly, most of the studied systems have been focused on the measurement of liquid solutes, and only a few studies have been

2. EXPERIMENTAL SECTION Materials. Acetylferrocene of 98 % purity was purchased from Acros Organics N.V. and was used as received. The IL [bmim][Tf2N] was purchased from Iolitec with 99 % purity and was further dried under vacuum in desiccator. The water content was measured to be less than 0.01 % using Karl Fischer. CO2 was supplied by HoekLoos B.V., with 99.99 % purity. Sample Preparation and Measurements. To keep the concentration of the solute constant in all experiments, a solution of 5.0 mol % of acetylferrocene in the IL [bmim][Tf2N] was prepared prior to the sample preparation. A synthetic method using the Cailletet apparatus was used to measure the phase behavior of the ternary system acetylferrocene + [bmim][Tf2N] + CO2. The main part of the apparatus is a Pyrex glass tube, which is called the Cailletet tube. The samples were dosed in the top of the Cailletet tube using a gas rack, and then the tube was mounted in the stainless steel Cailletet apparatus. The samples were stirred adequately using a stainless steel ball inside the tube which is activated by moving magnets. During all of the experiments, the temperature was kept constant, and the pressure was adjusted until a phase change occurred. The phase transitions of a sample with constant composition were observed visually. Experiments with water as a heat-transferring fluid were carried out in a temperature range of 278 K to 368 K. The Cailletet apparatus allows pressure measurements up to 15 MPa. The temperature was measured with an accuracy of ± 0.01 K, and pressures were taken with an accuracy of ± 0.003 MPa. Further information on sample preparation and experimental procedures is described in detail elsewhere.26 3. RESULTS AND DISCUSSION The phase behavior data for the ternary system containing acetylferrocene + [bmim][Tf2N] + CO2 in a temperature range of 278.36 K to 368.57 K and pressures up to 10.05 MPa are presented in Table 1. The concentration of acetylferrocene in [bmim][Tf2N] was maintained at a constant value of 5.0 mol % in all of the measurements. These data are graphically depicted in Figure 2. This figure shows the five different isopleths (10, 20, 31, 40, and 50 mol % of CO2) in a pressure-versustemperature diagram. Also, it is possible to recognize two different regions of liquid−vapor (LV) and liquid (L) in the acetylferrocene + [bmim][Tf2N] + CO2 system. From this figure, it can be seen that the LV → L transition moves to 952

dx.doi.org/10.1021/je301241k | J. Chem. Eng. Data 2013, 58, 951−955

Journal of Chemical & Engineering Data

Article

Table 1. Experimental Bubble-Point Data for Different Molar Fractions of CO2 (xCO2) in the System [bmim][Tf2N] + CO2 + 5.0 mol % Acetylferrocene (with Respect to the IL)a xCO2

T/K

P/MPa

T/K

P/MPa

0.1010

278.36 283.36 288.40 293.29 298.33 303.39 308.38 313.40 318.36 323.37 278.37 283.31 288.38 293.38 298.33 303.32 308.39 313.36 318.35 323.38 278.36 283.31 288.29 293.36 298.34 303.33 308.33 313.33 318.34 323.27 278.43 283.45 288.39 293.44 298.41 303.45 308.47 313.46 318.42 323.49 278.39 283.38 288.34 293.45 298.37 303.42 308.42 313.48 318.41 323.44

0.257 0.307 0.327 0.347 0.387 0.408 0.466 0.498 0.542 0.587 0.783 0.852 0.919 1.003 1.075 1.154 1.233 1.320 1.418 1.513 1.158 1.262 1.380 1.519 1.652 1.800 1.948 2.106 2.309 2.481 1.766 1.927 2.101 2.316 2.528 2.741 3.033 3.303 3.573 3.848 2.152 2.402 2.678 2.971 3.297 3.612 3.927 4.298 4.689 5.099

328.42 333.49 338.44 343.43 348.45 353.45 358.39 363.51 368.41

0.622 0.672 0.727 0.784 0.833 0.893 0.933 0.988 1.038

328.34 333.37 338.43 343.32 348.30 353.40 358.47 363.39 368.43

1.608 1.712 1.829 1.938 2.051 2.174 2.292 2.412 2.540

328.32 333.34 338.43 343.40 348.36 353.34 358.32 363.39 368.46

2.659 2.852 3.039 3.232 3.435 3.637 3.844 4.062 4.284

328.50 333.49 338.48 343.52 348.52 353.54 358.52 363.53 368.48

4.119 4.414 4.699 5.000 5.310 5.625 5.940 6.290 6.606

328.45 333.49 338.49 343.44 348.52 353.48 358.47 363.54 368.57

5.525 5.981 6.456 6.941 7.457 7.942 8.458 9.028 10.059

0.1997

0.3076

0.4010

0.5004

Figure 2. Experimental isopleths for the system acetylferrocene + [bmim][Tf2N] + CO2 at different CO2 concentrations: ◊, 10.10 mol %; □, 19.97 mol %; △, 30.76 mol %; +, 40.10 mol %; ○, 50.04 mol %.

temperature and pressure conditions, no solid−liquid or solid− vapor transitions were observed. To explore the effect of the addition of acetylferrocene to the binary system, Figure 3 illustrates the comparison between the

Figure 3. Comparison between isotherms for the binary system [bmim][Tf2N] + CO2 (filled symbols connected with dashed lines) and the ternary system acetylferrocene + [bmim][Tf2N] + CO2 (open symbols): □ and ■, 313.15 K; △ and ▲, 333.15 K; ○ and ●, 353.15 K. Dashed lines are polynomial fits to help the comparison.

binary system of [bmim][Tf2N] + CO213 and the ternary system acetylferrocene + [bmim][Tf2N] + CO2. Third-order polynomial equations were used to fit the data from Table 1, and interpolations at three different temperatures were used to plot isotherms. Figure 3 shows that the addition of acetylferrocene to the binary system of [bmim][Tf2N] + CO2 slightly decreases the solubility of CO2 in the ternary system. Moreover, it indicates that higher pressures are necessary to dissolve CO2 in the acetylferrocene + [bmim][Tf2N] system compared to [bmim][Tf2N] only. This behavior could be due to the reason that the acetylferrocene molecule and the IL [bmim][Tf2N] form stronger (polar) interactions compared to the interaction of [bmim][Tf2N] with CO2. This behavior of different organic compounds in presence of ILs and CO2 has been reported previously in literature.20,24 Additionally, from this figure one can clearly see the effect of the CO 2 concentrations on the pressure necessary to obtain a homogeneous phase. Previously, the phase behavior of ternary system ferrocene + [bmim][Tf2N] + CO2 was studied experimentally.28 As

a

Standard uncertainties u are u(T) = 0.01 K, u(p) = 0.003 MPa, and u(xCO2) = 0.005.

higher pressures with increasing CO2 concentrations. In other words, a higher pressure has to be applied to achieve a homogeneous liquid phase when more CO2 is added to the system. During these experiments and for the mentioned 953

dx.doi.org/10.1021/je301241k | J. Chem. Eng. Data 2013, 58, 951−955

Journal of Chemical & Engineering Data

Article

In summary, it can be concluded that the miscibility windows principle provides a useful tool to perform the acylation reaction of ferrocene into acetylferrocene in presence of IL [bmim][Tf2N] and CO2.

mentioned before, ferrocene is the reactant to produce acetylferrocene in the acylation reaction. To establish the optimum conditions to carry out the reaction and separation, it is essential to collect and to compare the phase behavior data for both systems. In Figure 4, a comparison between the

4. CONCLUSIONS In this work, the phase behavior of the ternary system consisting of the organometallic compound acetylferrocene in presence of the IL [bmim][Tf2N] and CO2 was studied for five different concentrations of CO2, ranging from 10 mol % up to 50 mol %. Acetylferrocene is the product of the Friedel−Crafts acylation reaction of ferrocene. From the results it was possible to recognize two regions (LV and L). By increasing the CO2 concentration the LV → L transition shifts to higher pressures. Comparison of the obtained ternary data with the binary data of [bmim][Tf 2 N] + CO 2 indicated that addition of acetylferrocene decreases the solubility of CO2 in the [bmim][Tf2N]. The reason could be due to the presence of stronger interactions between acetylferrocene and [bmim][Tf2N] compared to interactions between CO2 and [bmim][Tf2N]. A comparison between the ternary phase behavior data of acetylferrocene + [bmim][Tf2N] + CO2 with the ternary data of the system ferrocene + [bmim][Tf2N] + CO2, which we measured in our pervious study, elucidated that ternary systems containing solutes with similar molecular structure may show a completely different phase diagram. The experimental results of this study were also used to locate the homogeneous region for the reaction of ferrocene to acetylferrocene in IL + CO2 systems according to miscibility switch phenomenon. For example at 30 mol % of CO2, temperatures higher than 330 K and pressures higher than 5 MPa should be applied to maintain a homogeneous phase during the acylation reaction. In conclusion, the optimal operating conditions for the acylation reaction in IL + CO2 systems were successfully determined.

Figure 4. Comparison between isopleths for the ternary system acetylferrocene + [bmim][Tf2N] + CO2 (△, 30.76 mol % CO2; ○, 50.04 mol % CO2) and the ternary system ferrocene + [bmim][Tf2N] + CO228 (□, 29.98 mol % CO2; ◊, 50.05 mol % CO2). Open symbols represent SLV→SL transitions, solid symbols represent SL→L transitions, and dotted symbols represent LV→L transitions. Dashed lines are guide to the eye.

ternary system of ferrocene + [bmim][Tf2N] + CO2, which data were obtained in our previous study,28 and the ternary system acetylferrocene + [bmim][Tf2N] + CO2 is shown graphically. It was found before that four different phase regions are detectable in the ternary system of ferrocene + [bmim][Tf2N] + CO2: (i) a homogeneous liquid (L) phase, (ii) a twophase liquid−vapor (LV) region, (iii) a two-phase solid−liquid (SL) region, and (iv) a three-phase solid−liquid−vapor (SLV) region.27 However, only two regions were observed for the ternary system acetylferrocene + [bmim][Tf2N] + CO2. In other words, ferrocene precipitates as a solid by lowering the temperature while acetylferrocene is soluble in the solution at the same conditions. This behavior can be explained by the fact that acetylferrocene is more polar and has a lower melting point than ferrocene. The solubility of acetylferrocene in the pure [bmim][Tf2N] is higher than the solubility of ferrocene in the same IL, because of its higher polarity. Therefore, the low polar CO2 is expected to show higher interactions with ferrocene than with acetylferrocene. Indeed, the addition of CO2 results in an increase in ferrocene solubility28 and a decrease in acetylferrocene solubility. Moreover, it can be seen from Figure 4 that higher pressures are necessary to dissolve CO2 in the ternary system acetylferrocene + [bmim][Tf2N] + CO2 compared to the ternary system ferrocene + [bmim][Tf2N] + CO2. This behavior indicates the importance of studying the phase behavior of both reactant and product simultaneously in order to find the homogeneous region for the acylation reaction. Consequently, the best conditions to carry out the acylation reaction of ferrocene to acetylferrocene strongly depends on the CO2 concentrations in the system. For example, for a CO2 concentration of 30 mol % and temperatures higher than 330 K, and pressures higher than 5 MPa should be applied to maintain a homogeneous phase during the acylation reaction. Afterward, during the separation process the phase split could be achieved by pressure reduction.

■

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Phone: +31-40-2475289. Fax: +3140-2463966. Funding

Financial support by Agentschap NL is gratefully acknowledged. Notes

The authors declare no competing financial interest.

■ ■

ACKNOWLEDGMENTS The authors would like to thank Eugene Straver for technical support. REFERENCES

(1) Plazuk, D.; Zakrzewski, J. Friedel-Crafts acylation of ferrocene with alkynoic acids. J. Organomet. Chem. 2009, 694 (12), 1802−1806. (2) Fouda, M. F. R.; Abd-Eizaher, M. M.; Abdelsamaia, R. A.; Labib, A. A. On the medicinal chemistry of ferrocene. Appl. Organomet. Chem. 2007, 21 (8), 613−625. (3) Gao, Z. N.; Ma, J. F.; Liu, W. Y. Electrocatalytic oxidation of sulfite by acetylferrocene at glassy carbon electrode. Appl. Organomet. Chem. 2005, 19 (11), 1149−1154. (4) Gómez Arrayás, R.; Adrio, J.; Carretero, J. C. Recent applications of chiral ferrocene ligands in asymmetric catalysis. Angew. Chem., Int. Ed. 2006, 45 (46), 7674−7715.

954

dx.doi.org/10.1021/je301241k | J. Chem. Eng. Data 2013, 58, 951−955

Journal of Chemical & Engineering Data

Article

(5) Hu, R. J.; Lei, M.; Xiong, H. S.; Mu, X.; Wang, Y. G.; Yin, X. F. Highly selective acylation of ferrocene using microfluidic chip reactor. Tetrahedron Lett. 2008, 49 (2), 387−389. (6) Wasserscheid, P.;Welton, T. Ionic Liquids in Synthesis, 2nd ed.; Wiley-VCH: Weinheim, Germany, 2003. (7) Berardi, S.; Conte, V.; Fiorani, G.; Floris, B.; Galloni, P. Improvement of ferrocene acylation. Conventional vs. microwave heating for scandium-catalyzed reaction in alkylmethylimidazoliumbased ionic liquids. J. Organomet. Chem. 2008, 693 (18), 3015−3020. (8) Blanchard, L. A.; Gu, Z.; Brennecke, J. F. High-pressure phase behavior of ionic liquid/CO2 systems. J. Phys. Chem. B 2001, 105 (12), 2437−2444. (9) Blanchard, L. A.; Hancu, D.; Beckman, E. J.; Brennecke, J. F. Green processing using ionic liquids and CO2. Nature 1999, 398 (6731), 28−29. (10) Blanchard, L. A.; Brennecke, J. F. Recovery of organic products from ionic liquids using supercritical carbon dioxide. Ind. Eng. Chem. Res. 2001, 40 (1), 287−292. (11) Ram, B.; Gupta, J.-J. S. Solubility in Supercritical Carbon Dioxide; CRC Press: Boca Raton, FL, 2007. (12) Peters, C. J.; Gauter, K. Occurrence of Holes in Ternary Fluid Multiphase Systems of Near-Critical Carbon Dioxide and Certain Solutes. Chem. Rev. 1999, 99 (2−3), 419−431. (13) Raeissi, S.; Peters, C. J. Carbon dioxide solubility in the homologous 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide family. J. Chem. Eng. Data 2009, 54 (2), 382−386. (14) Shiflett, M. B.; Niehaus, A. M. S.; Elliott, B. A.; Yokozeki, A. Phase Behavior of N2O and CO2 in Room-Temperature Ionic Liquids [bmim][Tf2N], [bmim][BF4], [bmim][N(CN)2], [bmim][Ac], [eam][NO3], and [bmim][SCN]. Int. J. Thermophys. 2012, 1−25. (15) Keskin, S.; Kayrak-Talay, D.; Akman, U.; Hortaçsu, O. A review of ionic liquids towards supercritical fluid applications. J. Supercrit. Fluids 2007, 43 (1), 150−180. (16) Wang, W.; Yin, J. CO2/ionic liquids phase behaviors and its applications for reaction and separation. Prog. Chem. 2008, 20 (4), 441−449. (17) Aki, S. N. V. K.; Scurto, A. M.; Brennecke, J. F. Ternary phase behavior of ionic liquid (IL)-organic-CO2 systems. Ind. Eng. Chem. Res. 2006, 45 (16), 5574−5585. (18) Chobanov, K.; Tuma, D.; Maurer, G. High-pressure phase behavior of ternary systems (carbon dioxide + alkanol + hydrophobic ionic liquid). Fluid Phase Equilib. 2010, 294 (1−2), 54−66. (19) Kroon, M. C.; Florusse, L. J.; Peters, C. J. Phase behavior of the ternary 1-hexyl-3-methylimidazolium tetrafluoroborate + carbon dioxide + methanol system. Fluid Phase Equilib. 2010, 294 (1−2), 84−88. (20) Kühne, E.; Witkamp, G. J.; Peters, C. J. High-pressure phase behavior of ternary mixtures with ionic liquids, part I: The system bmim[BF4]+4-isobutylacetophenone + CO2. Green Chem. 2008, 10 (9), 929−933. (21) Kroon, M. C.; Florusse, L. J.; Kühne, E.; Witkamp, G. J.; Peters, C. J. Achievement of a homogeneous phase in ternary ionic liquid/ carbon dioxide/organic systems. Ind. Eng. Chem. Res. 2010, 49 (7), 3474−3478. (22) Kühne, E.; Calvo, E. S.; Witkamp, G. J.; Peters, C. J. Fluid phase behaviour of the ternary system bmim[BF4] + 1-(4-isobutylphenyl)ethanol + carbon dioxide. J. Supercrit. Fluids 2008, 45 (3), 293−297. (23) Kroon, M. C.; Toussaint, V. A.; Shariati, A.; Florusse, L. J.; Van Spronsen, J.; Witkamp, G. J.; Peters, C. J. Crystallization of an organic compound from an ionic liquid using carbon dioxide as anti-solvent. Green Chem. 2008, 10 (3), 341−344. (24) Kühne, E.; Perez, E.; Witkamp, G. J.; Peters, C. J. Solute influence on the high-pressure phase equilibrium of ternary systems with carbon dioxide and an ionic liquid. J. Supercrit. Fluids 2008, 45 (1), 27−31. (25) Kalenda, P. Ferrocene and some of its derivatives used as accelerators of curing reactions in unsaturated polyester resins. Eur. Polym. J. 1995, 31 (11), 1099−1102.

(26) Raeissi, S.; Peters, C. J. Bubble-point pressures of the binary system carbon dioxide + linalool. J. Supercrit. Fluids 2001, 20 (3), 221− 228. (27) Kazemi, S.; Baeta Martín, A.; Kroon, M. C.; Sordi, D.; Peters, C. J.; Arends, I. W. C. E. Vanadium-catalyzed Epoxidation Reaction of Cinnamyl Alcohol in Ionic Liquids. Green Process. Synth. 2012, 1, 509− 516. (28) Kazemi, S.; Peters, C. J.; Kroon, M. C. High pressure phase equilibria of the ternary system 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide + carbon dioxide + ferrocene. J. Supercrit. Fluids 2012, 69, 8−12.

955

dx.doi.org/10.1021/je301241k | J. Chem. Eng. Data 2013, 58, 951−955