METHOD FOR PREPARING CYCLIC CARBONATE

Abstract

The present invention provides a method for preparing a cyclic carbonate, which has the advantages of high yield, mild reaction conditions, high catalytic efficiency under room temperature and 1 atm pressure conditions, and wide substrate scopes. It is not only suitable for monosubstituted epoxides, but also suitable for disubstituted epoxides. The method comprises the step of reacting epoxides of Formula (I) with carbon dioxide in the presence of a quaternary ammonium salt and a catalyst, to obtain a cyclic carbonate of Formula (II). The reaction formula is:

##STR00001##

Claims

1. A method for preparing a cyclic carbonate, comprising a step of: reacting an epoxide of Formula (I) with carbon dioxide in the presence of a quaternary ammonium salt and a catalyst, to obtain a cyclic carbonate of Formula (II), the reaction formula being: ##STR00007## and the catalyst being an ethylenediamino bridged tetra(phenolate) rare earth-zinc heterobimetallic compound of Formula (III), ##STR00008## wherein: R.sub.1 and R.sub.2 are independently selected from the group consisting of hydrogen, an alkyl, alkoxy, aryl and ester group; or R.sub.1 and R.sub.2 are independently selected from alkyl and alkoxy, and R.sub.1 and R.sub.2, together with the atoms to which they are attached, form a ring; Ln is a rare earth metal ion.

2. The method for preparing a cyclic carbonate as claimed in claim 1, wherein the rare earth metal is yttrium, ytterbium or samarium.

3. The method for preparing a cyclic carbonate as claimed in claim 1, wherein the quaternary ammonium salt is selected from the group consisting of tetrabutylammonium iodide, tetrabutylammonium bromide, tetraoctylammonium bromide, bis(triphenylphosphine)ammonium chloride and any combination thereof.

4. The method for preparing a cyclic carbonate as claimed in claim 1, wherein the alkyl group is a substituted or non-substituted linear or branched C.sub.1-18 alkyl group, and the alkoxy group a substituted or non-substituted linear or branched C.sub.1-8 alkoxy group.

5. The method for preparing a cyclic carbonate as claimed in claim 1, wherein the aryl group is a substituted or non-substituted C.sub.6-14 aryl group; and the ester group is —COO—R.sub.3, in which R.sub.3 is H, C.sub.1-10 alkyl or aryl group.

6. The method for preparing a cyclic carbonate as claimed in claim 4, wherein the alkyl, alkoxy, or aryl group has one or more substituent(s) that is/are nitro, cyano, hydroxyl or halo, in which the halo is fluoro, chloro, bromo or iodo.

7. The method for preparing a cyclic carbonate as claimed in claim 1, wherein: R.sub.1 and R.sub.2, together with the atoms to which they are attached, form a C.sub.3-18 carbocyclic ring or a C.sub.2-17 heterocyclic ring containing an oxygen atom.

8. The method for preparing a cyclic carbonate as claimed in claim 1, wherein the temperature of addition reaction is 25-90° C.

9. The method for preparing a cyclic carbonate as claimed in claim 1, wherein a molar ratio of the bridged tetra(phenolate) rare earth-zinc heterobimetallic compound to the epoxide of Formula (I) is 1:100-500.

10. The method for preparing a cyclic carbonate as claimed in claim 1, wherein the catalyst of ethylenediamino bridged tetra(phenolate) rare earth-zinc heterobimetallic compound is synthesized by steps of: 1) synthesis of ethylenediamino bridged tetra(phenol) LH.sub.4: heating ethylenediamine, formaldehyde and 2,4-di-tert-butylphenol at 75-85° C. for 60-72 h to obtain the ethylenediamino bridged tetra(phenol) LH.sub.4, wherein the molar ratio of ethylenediamine, formaldehyde and 2,4-di-tert-butylphenol is 1:4:6-1:4:8; and the reaction formula is: ##STR00009## 2) synthesis of bridged tetra(phenolate) rare earth metal compound LLn (THF): reacting the ethylenediamino bridged tetra(phenol) with LnCp3(THF) in ether at 20-50° C. for 4-12 h in the absence of water and oxygen, to obtain the bridged tetra(phenolate) rare earth metal compound LLn(THF), wherein the molar ratio of the ethylenediamino bridged tetra(phenol) to LnCp.sub.3(THF) is 1:1-1:1.05, and the reaction formula is: ##STR00010## and 3) synthesis of bridged tetra(phenolate) rare earth-zinc heterobimetallic compound LnZnL(THF): reacting a solution of diethyl zinc in hexane or toluene with a solution of LnL(THF) in tetrahydrofuran at −5-50° C. for 8-12 h in the absence of water and oxygen, to obtain the bridged tetra(phenolate) rare earth-zinc heterobimetallic compound LnZnL(THF), wherein the molar ratio of diethyl zinc to LnL(THF) is 1:1-1.05:1, and the reaction formula is: ##STR00011##

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0050] The invention will be further illustrated in more detail with reference to the accompanying drawings and embodiments. It is noted that, the following embodiments only are intended for purposes of illustration, but are not intended to limit the scope of the present invention.

Embodiment 1

[0051] Preparation of bridged tetra(phenolate) rare earth metal compound YbL(THF):

[0052] (1) LH.sub.4 (2.80 g, 3.00 mmol) was dissolved in tetrahydrofuran, which was added to a solution of YCp.sub.3(THF) (1.31 g, 3.00 mmol) in tetrahydrofuran. The resulting solution was left for 4 h under stirring at room temperature, which gave a clear yellow solution.

[0053] (2) The solvent was removed, and hexane (10 mL) and tetrahydrofuran (0.5 mL) were added. The resulting solution was heated at 60° C., and centrifuged. The supernatant was transferred and allowed to stand at room temperature until yellow crystals (2.82 g, 2.39 mmol) precipitated (yield 80%). Melting point: 188-190° C. Element analysis: C, 67.50; H, 8.94; N, 2.47. IR spectrum (KBr, cm.sup.−1): 3423(s), 2960(w), 2904(s), 2869(s), 1603(s), 1479(s), 1442(s), 1411(s), 1362(s), 1304(s), 1282(s), 1238(s), 1204(s), 1166(s), 1132(s), 1026(s), 973(s), 912(s), 877(s), 833(s), 806(s), 759(s), 745(s), 671(s), 529(s), 458(s).

Embodiment 2

[0054] Preparation of Bridged Tetra(Phenolate) Rare Earth Metal Compound YL(THF):

[0055] (1) LH.sub.4 (2.80 g, 3.00 mmol) was dissolved in tetrahydrofuran, which was added to a solution of YCp.sub.3(THF) (1.07 g, 3.00 mmol) in tetrahydrofuran. The resulting solution was left for 4 h under stirring at room temperature, which gave a clear pale yellow solution.

[0056] (2) The solvent was removed, and toluene (15 mL) and tetrahydrofuran (0.5 mL) were added. The resulting solution was heated at 60° C., and centrifuged. The supernatant was transferred and allowed to stand at room temperature until colorless crystals (2.59 g, 2.37 mmol) precipitated (yield 79%). Melting point: 178-180° C. Element analysis: C, 72.59; H, 9.65; N, 2.62. IR spectrum (KBr, 3437(s), 2953(w), 2904(s), 2867(s), 1603(s), 1479(s), 1442(s), 1414(s), 1362(s), 1304(s), 1271(s), 1238(s), 1202(s), 1167(s), 1132(s), 1108(s), 974(s), 912(s), 875(s), 837(s), 805(s), 770(s), 744(s), 669(s), 533(s), 457(s). .sup.11-1 NMR spectrum (C.sub.6D.sub.6, δ): 7.52 (s, 4H, ArH), 6.93 (s, 4H, ArH) 4.32 (s, 4H, ArCH.sub.2N), 4.10 (br, 4H, ArCH.sub.2N), 2.93 (br, s, 4H, N—CH.sub.2—CH.sub.2—N), 1.53-1.36 (m, 72H, C(CH.sub.3).sub.3).

Embodiment 3

[0057] Preparation of Bridged Tetra(phenolate) Rare Earth Metal Compound SmL(THF):

[0058] (1) LH.sub.4 (2.80 g, 3.00 mmol) was dissolved in tetrahydrofuran, which was added to a solution of SmCp.sub.3(THF) (1.25 g, 3.00 mmol) in tetrahydrofuran. The resulting solution was left for 4 h under stirring at room temperature, which gave a clear yellow solution.

[0059] (2) The solvent was removed, and hexane (14 mL) and tetrahydrofuran (0.5 mL) were added. The resulting solution was heated at 60° C., and centrifuged. The supernatant was transferred and allowed to stand at room temperature until yellow crystal (2.50 g, 2.16 mmol) precipitated (yield 72%). Melting point: 199-201° C. Element analysis: C, 68.52; H, 8. 69; N, 2.53. IR spectrum (KBr, cm.sup.−1): 3423(s), 2960(w), 2904(s), 2869(s), 1603(s), 1477(s), 1440(s), 1414(s), 1362(s), 1301(s), 1276(s), 1240(s), 1202(s), 1167(s), 997(s), 969(s), 959(s), 913(s), 875(s), 833(s), 808(s), 770(s), 741(s), 691(s), 523(s), 435(s).

Embodiment 4

[0060] Preparation of Bridged Tetra(phenolate) Rare Earth-Zinc Heterobimetallic Compound ZnYL(THF):

[0061] (1) YL(THF) (3.27 g, 3.00 mmol) was dissolved in tetrahydrofuran, which was added to a solution of 3 mL diethyl zinc in hexane (1 mol/L). The resulting solution was left for 10 h under stirring at room temperature, which gave a clear yellow solution.

[0062] (2) The solvent was removed, and tetrahydrofuran (15 mL) was added. The resulting solution was heated at 60° C., and centrifuged. The supernatant was transferred and allowed to stand at room temperature until colorless crystal (2.59 g, 2.16 mmol) precipitated (yield 72%). Melting point: 205-207° C. Element analysis: C, 68.78; H, 9.00; N, 2.37. IR spectrum (KBr, cm.sup.-1): 3442(s), 2953(w), 2904(s), 2866(s), 1604(s), 1476(s), 1444(s), 1414(s), 1361(s), 1309(s), 1232(s), 1204(s), 1168(s), 1130(s), 1059(s), 1018(s), 972(s), 916(s), 872(s), 836(s), 803(s), 776(s), 745(s), 672(s), 613(s), 524(s), 444(s).

Embodiment 5

[0063] Catalytic Reaction of 1,2-Epoxyhexane with Carbon Dioxide in the Presence of 0.2% ZnYL(THF) and 0.8% Tetrabutylammonium Bromide

[0064] To a reaction flask, 1,2-epoxyhexane (2 mL, 0.0164 mol), ZnYL(THF) (0.0398 g, 3.36×10.sup.−5 mol), and tetrabutylammonium bromide (0.0443 g, 1.33×10.sup.−4 mol) were added, and a balloon containing carbon dioxide was connected. The reaction was heated for 24 h in an oil bath at 40° C. After reaction, a sample was taken and the yield was determined as 81% after analyzing by .sup.1H NMR spectroscopy.

Embodiment 6

[0065] Catalytic Reaction of 1,2-Epoxyhexane with Carbon Dioxide in the Presence of 0.2% ZnYL(THF) and 0.8% Tetraoctylammonium Bromide

[0066] To a reaction flask, 1,2-epoxyhexane (2 mL, 0.0164 mol), ZnYL(THF) (0.0398 g, 3.36×10.sup.−5 mol), and tetraoctylammonium bromide (0.0728 g, 1.33×10.sup.−4 mol) were added, and a balloon containing carbon dioxide was connected. The reaction was heated for 24 h in an oil bath at 40° C. Then the reaction flask was cooled in an ice bath, and the remaining carbon dioxide gas was discharged. A sample was taken and the yield was determined as 63% after analyzing by .sup.1H NMR spectroscopy.

Embodiment 7

[0067] Catalytic Reaction of 1,2-Epoxyhexane with Carbon Dioxide in the Presence of 0.2% ZnYL(THF) and 0.8% Tetrabutylammonium Iodide

[0068] To a reaction flask, 1,2-epoxyhexane (2 mL, 0.0164 mol), ZnYL(THF) (0.0398 g, 3.36×10.sup.−5 mol), and tetrabutylammonium iodide (0.0518 g, 1.33×10.sup.−4 mol) were added, and a balloon containing carbon dioxide was connected. The reaction was heated for 24 h in an oil bath at 40° C. Then the reaction flask was cooled in an ice bath, and the remaining carbon dioxide gas was discharged. A sample was taken and the yield was determined as 51% after analyzingby .sup.1HNMR spectroscopy.

Embodiment 8

[0069] Catalytic Reaction of 1,2-Epoxyhexane with Carbon Dioxide in the Presence of 1% ZnYL(THF) and 4% Tetrabutylammonium Bromide

[0070] To a reaction flask, 1,2-epoxyhexane (2 mL, 0.0164 mol), ZnYL(THF) (0.1942 g, 1.64×10.sup.−4 mol), and tetrabutylammonium bromide (0.2180 g, 6.56×10.sup.−4 mol) were added, and a balloon containing carbon dioxide was connected. The reaction was continued for 24 h in an oil bath at 25° C. The remaining carbon dioxide gas was discharged. A sample was taken and the yield was determined as 98% after analyzing by .sup.1H NMR spectroscopy.

Embodiment 9

[0071] Catalytic Reaction of 1,2-Epoxyhexane with Carbon Dioxide in the Presence of 0.5% ZnYL(THF) and 2% Tetrabutylammonium Bromide

[0072] To a reaction flask, 1,2-epoxyhexane (2 mL, 0.0164 mol), ZnYL(THF) (0.0971 g, 8.20×10.sup.−5 mol), and tetrabutylammonium bromide (0.1057 g, 3.28×10.sup.−4 mol) were added, and a balloon containing carbon dioxide was connected. The reaction was continued for 24 h in an oil bath at 25° C. The remaining carbon dioxide gas was discharged. A sample was taken and the yield was determined as 76% after analyzing by .sup.1H NMR spectroscopy.

Embodiment 10

[0073] Catalytic Reaction of 1,2-Epoxyhexane with Carbon Dioxide in the Presence of 1% ZnYL(THF) and 3% Tetrabutylammonium Bromide

[0074] To a reaction flask, 1,2-epoxyhexane (2 mL, 0.0164 mol), ZnYL(THF) (0.1942 g, 1.64×10.sup.−4 mol), and tetrabutylammonium bromide (0.1586 g, 4.92×10.sup.−4 mol) were added, and a balloon containing carbon dioxide was connected. The reaction was continued for 24 h in an oil bath at 25° C. The remaining carbon dioxide gas was discharged. A sample was taken and the yield was determined as 96% after analyzing by .sup.1H NMR spectroscopy.

Embodiment 11

[0075] Catalytic Reaction of 1,2-Epoxypropyl p-tert-butylbenzoate with Carbon Dioxide in the Presence of 1% ZnYL(THF) and 3% Tetrabutylammonium Bromide:

[0076] To a reaction flask, 1,2-epoxypropyl p-tert-butylbenzoate (2 mL, 0.0092 mol), ZnYL(THF) (0.1087 g, 9.20×10.sup.−5 mol), and tetrabutylammonium bromide (0.0914 g, 2.76×10.sup.−4 mol) were added, and a balloon containing carbon dioxide was connected. The reaction was continued for 40 h in an oil bath at 25° C. The remaining carbon dioxide gas was discharged. The reaction solution was mixed with dichloromethane (5 mL), and the product was isolated by flask column chromatography as a white solid (2.06 g, yield 80%).

Embodiment 12

[0077] Catalytic Reaction of 1,2-epoxydodecane with Carbon Dioxide in the Presence of 1% ZnYL(THF) and 3% Tetrabutylammonium Bromide

[0078] To a reaction flask, 1,2-epoxycyclododecane (1.8 mL, 0.0083 mol), ZnYL(THF) (0.0981 g, 8.30×10.sup.−5 mol), and tetrabutylammonium bromide (0.0825 g, 2.49×10.sup.−4 mol) were added, and a balloon containing carbon dioxide was connected. The reaction was continued for 40 h in an oil bath at 25° C. The reaction solution was mixed with dichloromethane (5 mL), the product was isolated by flask column chromatography as a white solid (1.78 g, yield 94%).

Embodiment 13

[0079] Catalytic Reaction of Epichlorohydrin with Carbon Dioxide in the Presence of 1% ZnYL(THF) and 3% Tetrabutylammonium Bromide

[0080] To a reaction flask, epichlorohydrin (1 mL, 0.0127 mol), ZnYL(THF) (0.1512 g, 1.27×10.sup.−4 mol), and tetrabutylammonium bromide (0.1266 g, 3.81×10.sup.−4 mol) were added, and a balloon containing carbon dioxide was connected. The reaction was continued for 24 h in an oil bath at 25° C. The reaction solution was mixed with dichloromethane (3 mL), the product was isolated by flask column chromatography as a colorless oil (1.21 g, yield 70%).

Embodiment 14

[0081] Catalytic Reaction of Styrene Oxide with Carbon Dioxide in the Presence of 1% ZnYL(THF) and 3% Tetrabutylammonium Bromide

[0082] To a reaction flask, styrene oxide (1 mL, 0.0084 mol), ZnYL(THF) (0.0992 g, 8.40×10.sup.−5 mol), and tetrabutylammonium bromide (0.0835 g, 2.52×10.sup.−4 mol) were added, and a balloon containing carbon dioxide was connected. The reaction was continued for 24 h in an oil bath at 25° C. The reaction solution was mixed with dichloromethane (3 mL), the product was isolated by flask column chromatography as a white solid (1.16 g, yield 84%).

Embodiment 15

[0083] Catalytic Reaction of 2,3-epoxypropyl n-propyl Ether with Carbon Dioxide in the Presence of 1% ZnYL(THF) and 3% Tetrabutylammonium Bromide

[0084] To a reaction flask, 2,3-epoxypropyl n-propyl ether (1.8 mL, 0.0152 mol), ZnYL(THF) (0.1795 g, 1.52×10.sup.−4 mol), and tetrabutylammonium bromide (0.1511 g, 4.56×10.sup.−4 mol) were added, and a balloon containing carbon dioxide was connected. The reaction was continued for 24 h in an oil bath at 25° C. The reaction solution was mixed with dichloromethane (5 mL), the product was isolated by flask column chromatography as a white solid (1.69 g, yield 84%).

Embodiment 16

[0085] Catalytic Reaction of Cyclopentene Oxide with Carbon Dioxide in the Presence of 1% ZnYL(THF) and 3% Tetrabutylammonium Bromide

[0086] To a reaction flask, cyclopentene oxide (1.8 mL, 0.0206 mol), ZnYL(THF)(0.1795 g, 2.06×10.sup.−4 mol), and tetrabutylammonium bromide (0.1511 g, 6.18×10.sup.−4 mol) were added. The mixed solution was added to a high-pressure reactor, which was sealed and into which 10 atm of carbon dioxide was then introduced. The reaction was continued for 24 h in an oil bath at 70° C. The reactor was cooled in an ice bath. The reaction solution was mixed with dichloromethane (5 mL), and the product was isolated by flask column chromatography as a colorless oil (2.32 g, yield 88%).

Embodiment 17

[0087] Catalytic Reaction of Stilbene Oxide with Carbon Dioxide in the Presence of 1% ZnYL(THF) and 3% Tetrabutylammonium Bromide

[0088] To a reaction flask, stilbene oxide (1 g, 0.0050 mol), the solvent n-butyl ketone (2 mL), ZnYL(THF)(0.0435 g, 5.01×10.sup.−5 mol), and tetrabutylammonium bromide (0.0498 g, 1.50×10.sup.−4 mol) were added. The mixed solution was added to a high-pressure reactor, which was sealed and into which 10 atm of carbon dioxide was then introduced. The reaction was continued for 40 h in an oil bath at 90° C. After reaction, the reactor was cooled in an ice bath. The product was isolated by flask column chromatography as a white solid (0.60 g, yield 50%).

Embodiment 18

[0089] Catalytic Reaction of 1,2-epoxytetrahydrofuran with Carbon Dioxide in the Presence of 1% ZnYL(THF) and 3% Tetrabutylammonium Bromide

[0090] To a reaction flask, 1,2-epoxytetrahydrofuran (0.8602 g, 0.0101 mol), ZnYL(THF) (0.0871 g, 1.00×10.sup.−4 mol), and tetrabutylammonium bromide (0.0996 g, 3.01×10.sup.−4 mol) were added. The mixed solution was added to a high-pressure reactor, which was sealed and into which 10 atm of carbon dioxide was then introduced. The reaction was continued for 24 h in an oil bath at 70° C. After reaction, the reactor was cooled in an ice bath. The product was isolated by flask column chromatography as a white solid (1.20 g, yield 92%).

[0091] The above description is only preferred embodiments of the present invention and not intended to limit the present invention. It should be noted that those of ordinary skill in the art can further make various modifications and variations without departing from the technical principles of the present invention, and these modifications and variations also should be considered to be within the scope of protection of the present invention.