Novel Electron-Rich and Sterically Hindered Phosphonium as a

Article Cite This: Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

pubs.acs.org/IECR

Novel Electron-Rich and Sterically Hindered Phosphonium as a Highly Efficient and Recyclable Heterogeneous Catalyst for CO2 Cycloaddition Xiaoming Yan, Rong Fu, Feng Liu, Yu Pan, Xuan Ding, and Gaohong He* State Key Laboratory of Fine Chemicals, School of Petroleum and Chemical Engineering, Dalian University of Technology, 2 Dagong Road, Panjin, Liaoning 124221, China ABSTRACT: A highly efficient heterogeneous catalyst is badly in need for producing cyclic carbonate by means of the CO2 cycloaddition. Here, a novel electron-rich and sterically hindered phosphonium heterogeneous catalyst was prepared by the functionalization of chloromethylated polystyrene particles with (2, 4, 6-trimethoxy phenyl) phosphine. Nine methoxyl groups not only endow the phosphonium with high electron density, which is demonstrated in X-ray photoelectron spectra, but also provide large steric hindrances between the anion and the cation. The unique phosphonium catalyst shows higher catalytic activities than all other reported ionic liquid based heterogeneous catalysts. It also exhibits a high selectivity and a good cycle performance. All these suggest that the phosphonium heterogeneous catalyst has the potential for practical applications in cycloadditions of CO2.

1. INTRODUCTION Carbon dioxide (CO2) is considered as good carbon feedstock to produce valuable chemicals because of the low cost, abundant reserves, and nontoxicity.1−3 Producing cyclic carbonates by means of the CO2 fixation is a desirable application.4,5 These five-membered ring products served as polar solvents, precursors in fine chemicals and polymers, electrolytes in lithium-ion secondary batteries, and so on.6 Since CO2 is thermodynamically inert, high-performance catalysts are required for the atom-economic coupling of CO2 with epoxides.7,8 In the past few years, numerous homogeneous catalysts, including functionalized ionic liquids (ILs),9 metallic catalysts,10−12 and alkali metal salts,13,14 were explored for this coupling reaction. With high tunability, good thermal stability, and negligible vapor pressure,15,16 IL catalysts attracted great attentions. It was indicated that some ILs could achieve high catalytic activities.17−24 However, these homogeneous catalysis processes have the issues in the terms of the catalyst recovery and product purification. The heterogeneous catalysis process enables an easy solid/ liquid separation,25 which can simplify the product purification process and also allow the convenient catalyst recycling. Recently, numbers of ILs, including ammnoum, imidazolium, and phophonium, were immobilized on the supporters to develop heterogeneous catalysts for coupling CO2 into epoxides.26−34 The catalytic activities of these heterogeneous catalysts are of concern, especially in the mild reaction condition (at low temperature or CO2 pressure). The introduction of cofunctional groups, such as amine, 35 hydroxide,36 and carboxyl groups,37 could improve the catalytic © XXXX American Chemical Society

activity. It is because hydrogen bond interactions between hydrogen atom in these cofunctional groups and the oxygen atom in epoxides could extend the C−O bond of epoxides, promoting the ring opening reaction of epoxides. The multifunctionalization per pendent chain in the supporter surface could also enhance the catalytic activity.21,38 In addition, making the IL groups far away from the supporter via the insertion of a long linking chain could increase the active area, thus accelerating the cycloaddition reaction.39 Although many efforts were made so far, developing highly active catalysts, especially for the epoxides containing electron-attracting or sterically hindered groups, is still a challenge. In the present work, a novel electron-rich and sterically hindered phosphonium heterogeneous catalyst was proposed for efficient productions of cyclic carbonates by means of the CO2 fixation. Compared to the phosphonium functionalized with triphenylphosphine, this unique phosphonium has nine methoxyl groups, which not only endow the phosphonium cation with high electron density, but also provide additional steric hindrances between the anion and the cation. This type of structure has two effects: one is enhancing the electronegativity of the anions; the other is weakening the bounding force between Br− and P+. Both of them could promote the attack of the anions on the epoxides. The high electron density also could facilitate the insertion of CO2. In addition, the weak bounding force between −OCOO− and P+ might promote the Received: Revised: Accepted: Published: A

January 3, 2018 February 1, 2018 February 7, 2018 February 7, 2018 DOI: 10.1021/acs.iecr.7b05419 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

Article

Industrial & Engineering Chemistry Research

Figure 1. Synthesis of phosphonium funtionalized catalyst.

the reactor was cooled to −10 °C, and the residual carbon dioxide was emancipated. The mixture was membrane-filter to get the product. The products were measured by Techcomp 7900 gas chromatograph equipping a FID detector and a DBwax capillary column (30 m × 0.25 mm × 0.25 μm).21 The procedure for the CO2 fixation reaction is shown in Figure 2.

cyclization reaction. On the basis of all these advantages, the unique phosphonium catalyst shows higher catalytic activity compared to other IL based heterogeneous catalysts.

2. EXPERIMENTAL SECTION 2.1. Materials. Spherical chloromethtlated polystyrene resin (CMPS, average diameter: 1 mm) with a Cl content of 17% was obtained from the Chemical Plant of NanKai University (China). Butylene oxide (BO), cyclohexene oxide (CO), 3chloropropylene oxide (ClPO), styrene oxide (SO), and triphenylphosphine (PPh3) were obtained from J&K Chemical. Propylene oxide (PO) was obtained from Sinopharm Chemical Reagent Co., Ltd. and purified by distillation prior to use. Tris (2,4,6-trimethoxyphenyl) phosphine (TTMPP) was obtained from Sigma-Aldrich Co, and 99.999% carbon dioxide and other chemical solvents were commercially available. 2.2. Catalyst Preparations. First, 1 g of CMPS microspheres was added into 30 mL of acetonitrile and preswelled overnight, and then the 5 mmol TTMPP was added. The mixture was stirred at 80 °C for another 12 h. Then the product microspheres were washed five times with ethyl acetate and then vacuum-dried at 60 °C for 12 h to get the product PS immobilized phosphonium chloride ([TTMPP-PS]Cl). The catalysts with the anion of Br− ([TTMPP-PS]Br) were obtained by the ion-exchange in saturated NaBr aqueous solution overnight. The catalysts with the anion of I − ([TTMPP-PS]I) were prepared by immersing the [TTMPPPS]Cl in saturated NaI solution at room temperature for 12 h. The [PPh3-PS]Cl catalyst was prepared using the same method to [TTMPP-PS]Cl except TTMPP replaced by PPh3. The synthesis of [TTMPP-PS]Br is presented in Figure 1. 2.3. Catalyst Characterizations. NOVA NanoSEM 450 microscope was used to observe scanning electron microscopic (SEM) images of samples. An accessory (INCA 250) of the NOVA NanoSEM 450 instrument captured the energy dispersive X-ray spectroscopy (EDX) spectra of samples. Mettler Toledo TGA/DSC instrument was used to obtain thermal gravimetric analysis (TGA) curves of samples at a heating rate of 10 °C min−1 in a N2 flow. The ESCALAB 250Xi spectrometer was used to perform X-ray photoelectron spectroscopy (XPS) of samples. 2.4. General Procedure for CO2 Fixation Reaction. For this procedure, 0.05, 0.15, 0.25, 0.45, 0.60, or 0.75 mol % (the ratio of catalyst active group to epoxide) catalyst was added into a 100 mL stainless-steel reactor. Next, the reactor was filled with CO2 and then exhausted when the pressure reached 4 MPa. This treatment process was repeated three times to remove the air in the reactor. Then 14.3 mmol epoxide (CO, BO, ClPO, SO, or PO) was added. The reactor was refilled with CO2 to 0.5, 1.0, 1.5, 2.0, 2.5, or 3 MPa. After heating at 90, 100, 110, 120, 130, or 140 °C for 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, or 3.5 h,

Figure 2. Procedure for the CO2 fixation reaction.

3. RESULTS AND DISCUSSION 3.1. Structure Characterizations. The Fourier transform infrared (FT-IR) spectra of CMPS and functionalized spheres are shown in Figure 3. In Figure 3a, the characteristic peak for

Figure 3. FT-IR spectra. (a) CMPS; (b) [PPh3-PS]Br; (c) [TTMPPPS]Br.

the C−H stretching vibration of the −CH2Cl appeared at 1265 cm−1. It disappeared in Figure 3b and c. The signals at 1441 and 1418 cm−1 in Figure 3b and c could be ascribed to stretching vibrations of P−C (Ar). The signals at 1090, 1125, 1211, and 1231 cm−1 in Figure 3c were assigned to C−O−C stretching vibrations. The signals at 1340 and 1455 cm−1 in Figure 3c were ascribed to the C−H stretching vibration of −CH3. The signals at 1570 and 1600 cm−1 in Figure 3c were attributed to the Ph−O vibrational modes. All these confirmed the successful syntheses of [PPh3-PS]Br and [TTMPP-PS]Br. Figure 4 shows SEM images of CMPS and [TTMPP-PS]Br. The surface of the resin was harshened with the introduction of [TTMPP]Br groups. The EDX surface element distributions of B

DOI: 10.1021/acs.iecr.7b05419 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

Article


Figure 4. SEM images. (a) CMPS and (b) [TTMPP-PS]Br.

Figure 5. EDX spectra: (a) P element image of [TTMPP-PS]Cl; (b) Br element image of [TTMPP-PS]Br; (c) I element image of [TTMPP-PS]I; (d) P and Cl contents of [TTMPP-PS]Cl; (e) P, Cl, and Br contents of [TTMPP-PS]Br; (f) P, Cl, and I contents of [TTMPP-PS]I.

be noted that although the I− has a poor stability under lighting conditions as we know, it has no effect on the thermal stability of the catalyst. Figure 7a shows the XPS surveys of the main chemical components. The O 1s peak of [TTMPP-PS]Br was at 531.8 eV, accompanied by a small amount of oxygen from the absorbed water of [PPh3-PS]Br and [TMA-PS]Br. The P 2p peak of [TTMPP-PS]Br appeared at 130.6 eV. The new peaks at 68.5 and 181.2 eV observed in the characteristic region could be assigned to the Br 3d5 and Br 3p3, respectively. The N 1s peak of the quaternary ammonium salt of [TMA-PS]Br appeared at 398.4 eV. To further elucidate the detailed chemical states of three heterogeneous catalysts, the deconvolutions of Br 3d spectra have been conducted, and the results are presented in Figure 7b−d, respectively. The Br spectra were separated into several peaks, the main and sharp signals are 3d5/2 and 3d3/2. In addition, the signal with the highest binding energy is associated with the oxidation Br that represented the Br−. [TTMPP-PS]Br shows the largest Br− peak area, suggesting the highest electronegativity of Br− for [TTMPP-PS]Br, thus the positive electricity of P+ and the forces between the cation and anion are both weakest for [TTMPP-PS]Br. On the basis of these, the nucleophilic performance of Br− for [TTMPP-PS]Br is strongest. 3.2. Catalytic Performances. The cycloaddition catalytic performances of the [TTMPP-PS]Brs on different types of epoxides with CO2 in the mild condition were investigated, and the results with the [TTMPP-PS]Br as the catalyst are listed in Table 1. The [TTMPP-PS]Br possesses catalytic activities for diversified epoxides. The cycloaddition reactions for all the

[TTMPP-PS]I, [TTMPP-PS]Br, and [TTMPP-PS]Cl were shown in Figure 5. The distributions of P, Br, and I elements in Figure 5a−c confirmed the successful functionalization and ionexchange processes. From Figure 5d−f, it could be seen that the molar ratios of I/Cl and Br/Cl are both above 99%, suggesting the nearly complete conversion from Cl− to Br− (or I−). Figure 6 shows the TGA curves of phosphonium functionalized catalysts. All three catalysts possess similar onset decomposition temperatures (∼150 °C) that can match the requirements for the application in the cycloaddition reactions. In addition, it can

Figure 6. TGA curves of [TTMPP-PS]Cl, [TTMPP-PS]Br, and [TTMPP-PS]I. C


Article


Figure 7. XPS spectra. (a) XPS surveys; (b) Br 3d XPS spectra of [TTMPP-PS]Br; (c) Br 3d XPS spectra of [PPh3-PS]Br; (d) Br 3d XPS spectra of [TMA-PS]Br.

Table 1. Fixation of CO2 with Different Epoxides Catalyzed by [TTMPP-PS]Bra

a

PO 14.3 mmol, catalyst 0.45 mol %, 120 °C, 2.5 h, and 1.0 MPa.

PO was selected as a representative compound to study cycloaddition catalytic performances of different catalysts. Table 2 listed the activities and selectivities of the reactions in a mild condition of 120 °C, 1.0 MPa, and 1.5 h. No activity and selectivity were observed for the cycloaddition reaction with the pristine CMPS as catalyst. The monomer of TTMPP produced a very low yield of 5.3%. [PPh3-PS]Cl accomplished a high selectivity of 99.4% but a yield of only 53.1%. In contrast, the [TTMPP-PS]Cl achieved a high yield of 85.5% that was much higher than that of [PPh3-PS]Cl, suggesting that [TTMPPPS]Cl had a much higher activity than [PPh3-PS]Cl. The [TTMPP-PS]Cl also exhibited a very high selectivity of 99.8%. The coupling reactivities of [TTMPP-PS]Xs with Cl, Br, and, I

epoxides show high selectivity of above 99%. The cycloaddition reaction for the propylene oxide exhibits the highest reactivity. The yield is a little lower for butylene oxide than for propylene oxide because of the bigger molecular weight of butylene oxide. The existence of the electron-attracting chloride atom at γ-C in the 3-chloropropylene oxide had a slightly negative effect on the reactivity. In contrast, the introduction of a highly electronattracting benzene at α-C or the large steric hindrance at β-C reduces the reactivity of epoxides. However, it should be noted that the yields for styrene oxide and cyclohexene oxide were still up to 98.4% and 85.7%, respectively, as the cycloaddition period was extended to 5 h. It again suggested the catalytic activity of [TTMPP-PS]X. D


Article

Industrial & Engineering Chemistry Research Table 2. Catalytic Performances of Various Catalystsa

a

entry

catalyst

yield (%)

selectivity (%)

1 2 3 4 5 6 7 8

CMPSb TTMPP [PPh3-PS]Cl [PPh3-PS]Br [TTMPP-PS]Cl [TTMPP-PS]Br [TTMPP-PS]I [TMA-PS]Br

5.3 53.1 60.1 85.5 90.4 93.1 45.6

98.5 99.4 99.5 99.8 99.8 99.8 99.0

cyclic carbonate.39−41 The yields for the catalysts with I− and Br− anions both exceed 90%. As we know, I− is unstable under lighting conditions. Therefore, the catalyst with Br− was selected in the further studies for convenience. [TTMPPPS]Br shows higher catalytic activity than [PPh3-PS]Br. Table 3 lists the catalytic performances of [TTMPP-PS]Br and other catalysts for CO, SO, and PO. [TTMPP-PS]Br shows the highest catalytic performances for all three epoxides in a moderate reaction condition, respectively. 3.3. Possible Explanation for High Efficiencies of [TTMPP-PS]X Catalysts. The high reactivity of [TTMPPPS]X catalysts might be explained from the CO2 cycloaddition reaction mechanism. A common mechanism is shown in Figure 8. First, the phosphonium cation activates the epoxide by the attack of the cation at the epoxide O to form an intermediate product (1). Then the nucleophilic X− anion attacks the β-C atom of the epoxide, which has less steric hindrance compared to the α-C. This attack leads to the epoxide ring opening to form an intermediate product (2). Afterward, CO2 is inserted

Catalyst 0.45 mol %, 120 °C, 1.5 h, and 1.0 MPa. bCMPS 0.1 g.

anions were compared. The catalysts with I− and Br− showed higher activities than that with Cl−, suggesting the catalytic activity depended on the halide’s nucleophilicity and leaving ability.39 The strongly nucleophilic anion gives an easy attack at the less sterically hindered β-C of the epoxide, and the leaving ability of halides is also indispensable for the generation of the

Table 3. Catalytic Performances of [TTMPP-PS]Br and Other Catalysts for CO, SO, and PO catalyst

a

this work

[TTMPP-PS]Br

Dai et al.42

PNPs-HPIL-3

Chen et al.20

CS-[BuPh3P]Br

Song et al.19

fluorous polymers R3P+X−

Sun et al.43

PS-HEIMX

Deng et al.21

[BisAm−OH-i-PS]Br2

Zhang et al.26

PDVB-CEIMBr

Zhang et al.24

FDU-HEIMBr

Watile et al.17

PS-DFILX

Paola Agrigento38

SiO2−octane−I

Zhang44 Liu et al.28

TBD/SiO2 NH2-Zn/SBA-15

Liu et al.45 Wu et al.31 Fu et al.46 Seok et al.47

Zn-SBA-15/KI HBimCl-NbCl5/HCMC Pd/C F-MIL-53-MeI

Kuruppathparambil et al.48

ZIF-67

Zhang et al.30

GO-HEIMBr

reaction conditions 120 120 120 140 140 120 120 120 150 150 120 120 125 130 130 130 140 140 140 110 110 110 130 130 150 150 150 120 130 150 120 130 120 120 120 120 120 140

°C, 1.0 MPa, 2.5 h °C, 1.0 MPa, 5 h °C, 1.0 MPa, 5 h °C, 2.0 MPa, 5 h °C, 2.0 MPa, 24 h °C, 2.5 MPa, 4 h °C, 2.5 MPa, 6 h °C, 2.5 MPa, 24 h °C, 8 MPa, 8 h °C, 8 MPa, 8 h °C, 2.5 MPa, 4 h °C, 2.5 MPa, 6 h °C, 2.5 MPa, 20 h °C, 1.2 MPa, 2.5 h °C, 1.2 MPa, 5 h °C,1.2 MPa, 5 h °C, 2 MPa, 4 h °C, 2 MPa, 4 h °C, 2 MPa, 4 h °C, 1 MPa, 3 h °C, 1 MPa, 5 h °C, 2 MPa, 24 h °C, 2 MPa, 3 h °C, 2 MPa, 15 h °C, 8 MPa, 3 h °C, 8 MPa, 3 h °C, 2 MPa, 20 h °C, 3 MPa, 12 h °C, 3 MPa, 12 h °C, 3 MPa, 18 h °C, 2.0 MPa, 12 h °C, 1.5 MPa, 3 h °C, 2 MPa, 8 h °C, 1.2 MPa, 6 h °C, 1.2 MPa, 6 h °C, 1.0 MPa, 6 h °C, 1.0 MPa, 6 h °C, 2.0 MPa, 4 h

epoxide PO SO CO SO CO PO SO CO PO SO PO SO CO PO SO CO PO SO CO PO SO CO PO CO SO CO PO PO SO CO CO PO PO CO PO SO CO PO

catalyst

30 30

30 30

0.45 mol % 0.45 mol % 0.45 mol % 0.47 mol % 0.47 mol % 1.5 mol % 1.5 mol % 1.5 mol % 1 mol % 1 mol % 1.6 mol % 1.6 mol % 1.6 mol % 0.75 mol % 0.75 mol % 0.75 mol % 0.44 mol % 0.44 mol % 0.44 mol % 0.5 mol % 0.5 mol % 0.5 mol % 0.2 g/25 mmol 0.2 g/25 mmol mg/14 mmol mg/14 mmol 0.8 g/12.45g 0.1 g/2.0 g 0.1 g/2.0 g 0.1 g/2.0 g 0.05 g + 0.3 mmol KI/34.5 mmol 0.1 g/10 mmol 0.1 mol %+ cocatalyst 0.4 mol % 1.6 mol % 1.6 mol % mg/25 mmol mg/25 mmol 0.35 mol %

yield (%) 99.6 98.4 85.7 90.7 46.8 96.3 96.9 74.3 98 95 98 93 80 99.1 94.4 64.7 97.4 93.8 70.4 99 95 70 97 85 85a 10 99.5a 93 71 13 36 98.1 98.8 6.3 92.0 73a 8a 99a

Conversion. E


Article


3.4. Effect of Reaction Parameters. The yield of PC at different temperatures for [TTMPP-PS]Br is presented in Figure 9a. At < 120 °C, the PC yield showed a dramatic increase with temperature, and then grew at a slow speed at > 120 °C. The influence of initial CO2 pressure on the catalytic performance of [TTMPP-PS]Br was studied. As shown in Figure 9b, the yield increased from 97.8% to 99.7% with the pressure rising from 0.5 to 1.0 MPa, but deceased at >1.5 MPa. A possible explanation for this trend is increasing the pressure could increase the CO2 concentration in the reaction mixture; however, too high CO2 concentration would isolate the catalysts from the POs, causing a decline of the reaction rate.21 Figure 9c represents PC yield and selectivity as a function of reaction time. The yield increased with the cycloaddition time, and the reaction reached thermodynamic equilibrium at 2.5 h. As presented in Figure 9d, increasing catalyst dosage could improve the PC yield. An appropriate dosage is 0.45 mol %. In addition, it can be noted that the selectivity was always above 99.7% in all reaction conditions, suggesting that the temperature, pressure, reaction time, and catalyst dosage had no significant effects on the selectivity. Since [TTMPP-PS]Cl may have a better long-term stability, the influences of reaction parameters on the reactions with [TTMPP-PS]Cl as catalyst were also investigated. It was found that the yield reached 97.3% under the condition: PO 14.3 mmol, [TTMPP-PS]Br 0.45 mol %, 130 °C, 2.5 h, and 1.5 MPa. 3.5. Catalyst Recovery. The long-term stability of catalysts is very important for the practical applications. The recyclabilities of [TTMPP-PS]Br and [TTMPP-PS]Cl were carried out. The catalysts were retrieved by filtration after the cycloaddition. Figure 10 showed that the selectivity was always above 99.7%. The PC yield had almost no change for the first six consecutive cycles, and then slightly decreased for the next four cycles. The PC yield was still up to 97.1% after 10 cycles, suggesting that the [TTMPP-PS]Br catalyst had a good recyclability of the cycloaddition reaction. As shown in Figure 11, the PC yield for the reaction with [TTMPP-PS]Cl as catalyst showed no obvious change for 10 cycles. It indicates

Figure 8. Mechanism for the cycloaddition reaction.

into the intermediate by the reaction between the −O− and the C atom of CO2, forming the carbonate intermediate (3). Finally, the PC is produced through the intramolecular cyclization reaction, and the catalyst [TTMPP-PS]X is regenerated. Compared to [PPh3-PS]X, [TTMPP-PS]X has nine electron-donating methoxyl groups in three benzene rings of phosphonium groups. The existence of these methoxyl groups not only dramatically enhances the electron density of the phosphonium cation, but also provides additional steric hindrance between anion and cation. This type of structure has two interactions: one is enhancing the electronegativity of the anions; the other is weakening the bounding force between the anion and the center cation. According to the reaction mechanism, both of them could promote the attack of the anions on the epoxides, accelerating the formation of the intermediate product (2). The high electron could also weaken the bounding force between the center P+ and the −O−, which makes the insertion of CO2 easier. In addition, the weak binding force of the P+ to the −OCOO− might promote the cyclization reaction. All these positive effects contributes to the high catalytic activity of the [TTMPP-PS]X catalyst.

Figure 9. Effects of different parameters on PC selectivity and yield: (a) reaction temperature (catalyst 0.45 mol %, 1.0 MPa, 2.5 h); (b) reaction pressure (catalyst 0.45 mol %, 120 °C, 2.5 h); (c) reaction time (catalyst 0.45 mol %, 120 °C, 1.0 MPa); (d) catalyst dosage (120 °C, 1.0 MPa, 2 0.5 h). F



■

Article

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Phone: +86 427 2631803. Fax: +86 427 2631803. ORCID

Xiaoming Yan: 0000-0002-5263-9952 Gaohong He: 0000-0002-6674-8279 Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS The authors thank the National Natural Science Foundation of China (Grant Nos. 21406031, 21404018, and U1663223) and the Changjiang Scholars Program (Grant No. T2012049) for financial support.

Figure 10. Recyclability of [TTMPP-PS]Br (catalyst 0.45 mol %, 120 °C, 1.0 MPa, 2.5 h).

■

REFERENCES

(1) North, M.; Pasquale, R.; Young, C. Synthesis of cyclic carbonates from epoxides and CO2. Green Chem. 2010, 12, 1514−1539. (2) Lan, D. H.; Wang, H. T.; Chen, L.; Au, C. T.; Yin, S. F. Phosphorous-modified bulk graphitic carbon nitride: Facile preparation and application as an acid-base bifunctional and efficient catalyst for CO2 cycloaddition with epoxides. Carbon 2016, 100, 81−89. (3) Li, C.; Wang, W.; Yan, L.; Wang, Y.; Jiang, M.; Ding, Y. Phosphonium salt and ZnX2−PPh3 integrated hierarchical POPs: tailorable synthesis and highly efficient cooperative catalysis in CO2 utilization. J. Mater. Chem. A 2016, 4, 16017−16027. (4) Whiteoak, C. J.; Kielland, N.; Laserna, V.; Escudero-Adan, E. C.; Martin, E.; Kleij, A. W. A Powerful Aluminum Catalyst for the Synthesis of Highly Functional Organic Carbonates. J. Am. Chem. Soc. 2013, 135, 1228−1231. (5) Peng, J.; Yang, H. J.; Geng, Y.; Wei, Z.; Wang, L.; Guo, C. Y. Novel, recyclable supramolecular metal complexes for the synthesis of cyclic carbonates from epoxides and CO2 under solvent-free conditions. J. CO2 Util. 2017, 17, 243−255. (6) Laserna, V.; Fiorani, G.; Whiteoak, C. J.; Martin, E.; EscuderoAdan, E.; Kleij, A. W. Carbon Dioxide as a Protecting Group: Highly Efficient and Selective Catalytic Access to Cyclic cis-Diol Scaffolds. Angew. Chem., Int. Ed. 2014, 53, 10416−10419. (7) Maeda, C.; Miyazaki, Y.; Ema, T. Recent progress in catalytic conversions of carbon dioxide. Catal. Sci. Technol. 2014, 4, 1482− 1497. (8) Lu, X. B.; Darensbourg, D. J. Cobalt catalysts for the coupling of CO2 and epoxides to provide polycarbonates and cyclic carbonates. Chem. Soc. Rev. 2012, 41, 1462−1484. (9) He, Q.; O’Brien, J. W.; Kitselman, K. A.; Tompkins, L. E.; Curtis, G. C. T.; Kerton, F. M. Synthesis of cyclic carbonates from CO2 and epoxides using ionic liquids and related catalysts including choline chloride-metal halide mixtures. Catal. Sci. Technol. 2014, 4, 1513− 1528. (10) Alhashmialameer, D.; Collins, J.; Hattenhauer, K.; Kerton, F. M. Iron amino-bis(phenolate) complexes for the formation of organic carbonates from CO2 and oxiranes. Catal. Sci. Technol. 2016, 6, 5364− 5373. (11) Verma, S.; Kureshy, R. I.; Roy, T.; Kumar, M.; Das, A.; Khan, N.-u. H.; Abdi, S. H. R.; Bajaj, H. C. Immobilization of cationic Al(III) salen in the interlayers of montmorillonite clay for the synthesis of cyclic carbonate. Catal. Commun. 2015, 61, 78−82. (12) Ramidi, P.; Sullivan, S. Z.; Gartia, Y.; Munshi, P.; Griffin, W. O.; Darsey, J. A.; Biswas, A.; Shaikh, A. U.; Ghosh, A. Catalytic Cyclic Carbonate Synthesis Using Epoxide and Carbon Dioxide: Combined Catalytic Effect of Both Cation and Anion of an Ionic Cr-v(O) Amido Macrocyclic Complex. Ind. Eng. Chem. Res. 2011, 50, 7800−7807. (13) Calo, V.; Nacci, A.; Monopoli, A.; Fanizzi, A. Cyclic carbonate formation from carbon dioxide and oxiranes in tetrabutylammonium halides as solvents and catalysts. Org. Lett. 2002, 4, 2561−2563.

Figure 11. Recyclability of [TTMPP-PS]Cl (catalyst 0.45 mol %, 130 °C, 1.5 MPa, 2.5 h).

that the [TTMPP-PS]Cl has a better stability than [TTMPPPS]Br. The recyclability of the catalyst was also investigated in another mode. A second batch of PO was put into the reactor without taking out the reaction mixture and the catalyst after the reaction. Then the reaction was conducted again under the same condition. The yield for the second batch was 96.8% that was a little lower than that for the first (99.7%). The reason for the decreased yield might be that the concentration of PO for the second batch was 1/2 that for the first.

4. CONCLUSIONS A novel electron-rich and sterically hindered phosphonium ([TTMPP-PS]X) heterogeneous catalyst was prepared by the reaction of chloromethylated polystyrene particles and (2,4,6trimethoxy phenyl) phosphine for the CO2 fixation reaction. XPS spectra indicate that the Br− of [TTMPP-PS]Br has the highest electron density. The unique phosphonium catalyst exhibited high catalytic performance in a moderate condition. The cycloadditions of propylene oxide, styrene oxide, and cyclohexene oxide under 1.0 MPa at 120 °C for 2.5 h showed the yields of 99.6%, 98.4%, and 85.7% that were higher than those using other reported IL based heterogeneous catalysts, respectively. The phosphonium catalyst also exhibited high selectivity (>99%) for the cycloadditions of all selected epoxides. In addition, [TTMPP-PS]Br possessed a good cycle performance, and both the selectivity and yield for propylene carbonate were more than 99% after six times recycled. G


Article

Industrial & Engineering Chemistry Research (14) Song, J.; Zhang, Z.; Han, B.; Hu, S.; Li, W.; Xie, Y. Synthesis of cyclic carbonates from epoxides and CO2 catalyzed by potassium halide in the presence of beta-cyclodextrin. Green Chem. 2008, 10, 1337−1341. (15) Xie, H.; Zhang, S.; Li, S. Chitin and chitosan dissolved in ionic liquids as reversible sorbents of CO2. Green Chem. 2006, 8, 630. (16) Xie, H.; Li, S.; Zhang, S. Highly active, hexabutylguanidinium salt/zinc bromide binary catalyst for the coupling reaction of carbon dioxide and epoxides. J. Mol. Catal. A: Chem. 2006, 250, 30−34. (17) Watile, R. A.; Deshmukh, K. M.; Dhake, K. P.; Bhanage, B. M. Efficient synthesis of cyclic carbonate from carbon dioxide using polymer anchored diol functionalized ionic liquids as a highly active heterogeneous catalyst. Catal. Sci. Technol. 2012, 2, 1051−1055. (18) Wang, W.; Li, C.; Yan, L.; Wang, Y.; Jiang, M.; Ding, Y. Ionic Liquid/Zn-PPh3 Integrated Porous Organic Polymers Featuring Multifunctional Sites: Highly Active Heterogeneous Catalyst for Cooperative Conversion of CO2 to Cyclic Carbonates. ACS Catal. 2016, 6, 6091−6100. (19) Song, Q. W.; He, L. N.; Wang, J. Q.; Yasuda, H.; Sakakura, T. Catalytic fixation of CO2 to cyclic carbonates by phosphonium chlorides immobilized on fluorous polymer. Green Chem. 2013, 15, 110−115. (20) Chen, J. X.; Jin, B.; Dai, W. L.; Deng, S. L.; Cao, L. R.; Cao, Z. J.; Luo, S. L.; Luo, X. B.; Tu, X. M.; Au, C. T. Catalytic fixation of CO2 to cyclic carbonates over biopolymer chitosan-grafted quarternary phosphonium ionic liquid as a recylable catalyst. Appl. Catal., A 2014, 484, 26−32. (21) Deng, Q.; He, G.; Pan, Y.; Ruan, X.; Zheng, W.; Yan, X. Bisammonium immobilized polystyrenes with co-catalyzing functional end groups as efficient and reusable heterogeneous catalysts for synthesis of cyclic carbonate from CO2 and epoxides. RSC Adv. 2016, 6, 2217−2224. (22) Motokura, K.; Itagaki, S.; Iwasawa, Y.; Miyaji, A.; Baba, T. Silicasupported aminopyridinium halides for catalytic transformations of epoxides to cyclic carbonates under atmospheric pressure of carbon dioxide. Green Chem. 2009, 11, 1876−1880. (23) Amaral, A. J. R.; Coelho, J. F. J.; Serra, A. C. Synthesis of bifunctional cyclic carbonates from CO2 catalysed by choline-based systems. Tetrahedron Lett. 2013, 54, 5518−5522. (24) Zhang, W.; Wang, Q.; Wu, H.; Wu, P.; He, M. A highly ordered mesoporous polymer supported imidazolium-based ionic liquid: an efficient catalyst for cycloaddition of CO2with epoxides to produce cyclic carbonates. Green Chem. 2014, 16, 4767−4774. (25) Zhu, A.; Jiang, T.; Han, B.; Zhang, J.; Xie, Y.; Ma, X. Supported choline chloride/urea as a heterogeneous catalyst for chemical fixation of carbon dioxide to cyclic carbonates. Green Chem. 2007, 9, 169−172. (26) Zhang, Y.; Yin, S.; Luo, S.; Au, C. T. Cycloaddition of CO2 to Epoxides Catalyzed by Carboxyl-Functionalized Imidazolium-Based Ionic Liquid Grafted onto Cross-Linked Polymer. Ind. Eng. Chem. Res. 2012, 51, 3951−3957. (27) Xiao, L. F.; Li, F. W.; Peng, H. H.; Xia, C. G. Immobilized ionic liquid/zinc chloride: Heterogeneous catalyst for synthesis of cyclic carbonates from carbon dioxide and epoxides. J. Mol. Catal. A: Chem. 2006, 253, 265−269. (28) Liu, M.; Liu, B.; Liang, L.; Wang, F.; Shi, L.; Sun, J. Design of bifunctional NH3I-Zn/SBA-15 single-component heterogeneous catalyst for chemical fixation of carbon dioxide to cyclic carbonates. J. Mol. Catal. A: Chem. 2016, 418-419, 78−85. (29) Xu, J.; Xu, M.; Wu, J.; Wu, H.; Zhang, W. H.; Li, Y. X. Graphene oxide immobilized with ionic liquids: facile preparation and efficient catalysis for solvent-free cycloaddition of CO2 to propylene carbonate. RSC Adv. 2015, 5, 72361−72368. (30) Zhang, W. H.; He, P. P.; Wu, S.; Xu, J.; Li, Y.; Zhang, G.; Wei, X. Y. Graphene oxide grafted hydroxyl-functionalized ionic liquid: A highly efficient catalyst for cycloaddition of CO2 with epoxides. Appl. Catal., A 2016, 509, 111−117. (31) Wu, X.; Wang, M.; Xie, Y.; Chen, C.; Li, K.; Yuan, M.; Zhao, X.; Hou, Z. Carboxymethyl cellulose supported ionic liquid as a

heterogeneous catalyst for the cycloaddition of CO2 to cyclic carbonate. Appl. Catal., A 2016, 519, 146−154. (32) Roshan, K. R.; Mathai, G.; Kim, J.; Tharun, J.; Park, G. A.; Park, D. W. A biopolymer mediated efficient synthesis of cyclic carbonates from epoxides and carbon dioxide. Green Chem. 2012, 14, 2933−2940. (33) Song, J.; Zhang, Z.; Hu, S.; Wu, T.; Jiang, T.; Han, B. MOF-5/nBu4NBr: an efficient catalyst system for the synthesis of cyclic carbonates from epoxides and CO2 under mild conditions. Green Chem. 2009, 11, 1031−1036. (34) Liu, Z. L.; Teng, Y.; Zhang, K.; Chen, H. G.; Yang, Y. P. CO2 adsorption performance of different amine-based siliceous MCM-41 materials. J. Energy Chem. 2015, 24, 322−330. (35) Lee, S. D.; Kim, B. M.; Kim, D. W.; Kim, M. I.; Roshan, K. R.; Kim, M. K.; Won, Y. S.; Park, D. W. Synthesis of cyclic carbonate from carbon dioxide and epoxides with polystyrene-supported quaternized ammonium salt catalysts. Appl. Catal., A 2014, 486, 69−76. (36) Ma, J.; Liu, J.; Zhang, Z.; Han, B. The catalytic mechanism of KI and the co-catalytic mechanism of hydroxyl substances for cycloaddition of CO2 with propylene oxide. Green Chem. 2012, 14, 2410− 2420. (37) Cheng, W.; Chen, X.; Sun, J.; Wang, J.; Zhang, S. SBA-15 supported triazolium-based ionic liquids as highly efficient and recyclable catalysts for fixation of CO2 with epoxides. Catal. Today 2013, 200, 117−124. (38) Agrigento, P.; Al-Amsyar, S. M.; Sorée, B.; Taherimehr, M.; Gruttadauria, M.; Aprile, C.; Pescarmona, P. P. Synthesis and highthroughput testing of multilayered supported ionic liquid catalysts for the conversion of CO2and epoxides into cyclic carbonates. Catal. Sci. Technol. 2014, 4, 1598−1607. (39) Yan, X. M.; Ding, X.; Pan, Y.; Xu, X. W.; Hao, C.; Zheng, W. J.; He, G. H. Quaternary-ammonium-immobilized polystyrenes as efficient and reusable heterogeneous catalysts for synthesis of cyclic carbonate: Effects of linking chains and pendent hydroxyl group. Chin. J. Catal. 2017, 38, 862−871. (40) Castro-Gomez, F.; Salassa, G.; Kleij, A. W.; Bo, C. A DFT study on the mechanism of the cycloaddition reaction of CO2 to epoxides catalyzed by Zn(salphen) complexes. Chem. Chem. - Eur. J. 2013, 19, 6289−98. (41) Sun, H.; Zhang, D. J. Density functional theory study on the cycloaddition of carbon dioxide with propylene oxide catalyzed by alkylmethylimidazolium chlorine ionic liquids. J. Phys. Chem. A 2007, 111, 8036−8043. (42) Dai, W. L.; Zhang, Y.; Tan, Y.; Luo, X. B.; Tu, X. M. Reusable and efficient polymer nanoparticles grafted with hydroxyl-functionalized phosphonium-based ionic liquid catalyst for cycloaddition of CO2 with epoxides. Appl. Catal., A 2016, 514, 43−50. (43) Sun, J.; Cheng, W.; Fan, W.; Wang, Y.; Meng, Z.; Zhang, S. Reusable and efficient polymer-supported task-specific ionic liquid catalyst for cycloaddition of epoxide with CO2. Catal. Today 2009, 148, 361−367. (44) Zhang, X.; Zhao, N.; Wei, W.; Sun, Y. Chemical fixation of carbon dioxide to propylene carbonate over amine-functionalized silica catalysts. Catal. Today 2006, 115, 102−106. (45) Liu, M.; Gao, K.; Liang, L.; Sun, J.; Sheng, L.; Arai, M. Experimental and theoretical insights into binary Zn-SBA-15/KI catalysts for the selective coupling of CO2 and epoxides into cyclic carbonates under mild conditions. Catal. Sci. Technol. 2016, 6, 6406− 6416. (46) Fu, X. Y.; Zhou, D. G.; Wang, K.; Jing, H. W. Pd/C as a high efficient and reusable catalyst for cycloaddition of CO2 to epoxides. J. CO2 Util. 2016, 14, 31−36. (47) Seok, H. G.; Kim, D. W.; Yang, J. G.; Kim, M. I.; Park, D. W. Catalytic Performance of Microwave Functionalized NH2-MIL-53 for Cyclic Carbonate Synthesis from CO2 and Epoxides. J. Nanosci. Nanotechnol. 2016, 16, 4612−4619. (48) Kuruppathparambil, R. R.; Jose, T.; Babu, R.; Hwang, G. Y.; Kathalikkattil, A. C.; Kim, D. W.; Park, D. W. A room temperature synthesizable and environmental friendly heterogeneous ZIF-67 H


Article

Industrial & Engineering Chemistry Research catalyst for the solvent less and co-catalyst free synthesis of cyclic carbonates. Appl. Catal., B 2016, 182, 562−569.

I


Novel Electron-Rich and Sterically Hindered Phosphonium as a

Recommend Documents