CATALYSTS FOR SYNTHESIZING CYCLIC CARBONATES, PREPARATION METHODS AND USES THEREOF

Abstract

The present invention provides a catalyst for synthesizing a cyclic carbonate and a preparation method and use thereof. A diamine compound X, a salicylaldehyde-containing compound and a metal source M are subjected to reaction, and then added with a phenothiazine compound Y for continuous reaction to obtain a phenothiazine metal Schiff base catalyst. The formation of phenothiazine free radicals by phenothiazine compounds with a central metal can protect the central metal in the course of reaction and inhibit inactivation caused by the self-polymerization of the central meta, thus improving the activity and stability of a catalyst. Phenothiazine compounds can be present as a polymerization inhibitor to inhibit the generation of by-products such as polycarbonates and polyethylene glycol and enhance the selectivity of the catalyst during the reaction. The phenothiazine compounds are alkaline and can adsorb and activate carbon dioxide during reaction, which helps to improve the reaction efficiency. The phenothiazine metal Schiff base catalyst prepared in the present invention has high activity, strong stability and good selectivity and thus, can achieve the efficient catalyzed synthesis of cyclic carbonates under mild conditions.

Claims

1. A catalyst for synthesizing an ethylene carbonate, having a structural formula of: ##STR00020## in the formula, Mis a metal ion; X is one of the following structures: ##STR00021## the represents connection bounding to N atoms Y is a phenothiazine structure; R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are H, alkyl, halogen, or nitryl; wherein R.sub.1=R.sub.4, R.sub.2=R.sub.3;.

2. The catalyst for synthesizing an ethylene carbonate according to claim 1, wherein Y is one or more of the following structural formulas: ##STR00022## the represents connection bounding to N atoms.

3. A method for preparing the catalyst for synthesizing an ethylene carbonate according to claim 1, comprising the following steps: 1) under the protection of nitrogen, dissolving a diamine compound and a salicylaldehyde-containing compound into an organic solvent, adding a metal source, and adding an organic acid as a catalyst, and heating for reflux reaction; and 2) adding a phenothiazine compound Y to continue the reaction, and conducting separation and purification to obtain the catalyst for synthesizing the ethylene carbonate; wherein the metal source is selected from one of Al.sup.3+, Zn.sup.2+, Fe.sup.3+, Co.sup.2+, Mn.sup.2+, Ni.sup.2+, Mg.sup.2+, Cr.sup.3+, or Ca.sup.2+.

4. The preparation method according to claim 3, wherein the diamine compound, the salicylaldehyde-containing compound, the metal source, the organic acid, and the phenothiazine compound have a molar ratio of 1:2:1:0.0001-0.02:1-1.5.

5. The preparation method according to claim 3, wherein the salicylaldehyde-containing compound has a structural formula of: ##STR00023## R.sub.1 and R.sub.2 in the structural formula are selected from H, CH.sub.3, C(CH.sub.3).sub.3, F, Cl, Br, NO.sub.2; or OCH CH.sub.3; and R.sub.1 and R.sub.2 are the same or different.

6. (canceled)

7. The preparation method according to claim 3, wherein the organic acid is selected from formic acid, acetic acid, propionic acid, butyric acid, ethanedioic acid, butanedioic acid, tartaric acid, benzoic acid, or oxalic acid.

8. The preparation method according to claim 3, wherein in the step 2), the phenothiazine compound is added to continue the reaction for 1-12 h.

9. (canceled)

10. (canceled)

11. A method of making an ethylene carbonate with the catalyst according to claim 1, comprising the following steps: 1) mixing the catalyst for synthesizing the ethylene carbonate with a quaternary ammonium salt cocatalyst in a high-pressure reactor, replacing air in the reactor with carbon dioxide, the molar ratio of the integral molar quantity of the catalyst for synthesizing the ethylene carbonate and the quaternary ammonium salt cocatalyst to the molar quantity of ethylene oxide is 1:500-1:500,000; introducing carbon dioxide after adding the ethylene oxide, the reaction system is maintained at a pressure of 0.1-5.0 MPa, stirred and heated up to 20-180 C. for reaction for 1-72h; 2) stopping the stirring, cooling to room temperature, emptying unreacted carbon dioxide, and isolating reactor liquid via distillation under reduced pressure to obtain a ethylene carbonate product.

12. The method according to claim 11, wherein the quaternary ammonium salt cocatalyst is tetrabutylammonium bromide, the catalyst for synthesizing a the ethylene carbonate and the quaternary ammonium salt cocatalyst have a molar ratio of 1:1-1:100; the epoxide is ethylene oxide.

Description

DESCRIPTION OF THE EMBODIMENTS

[0042] To make the objectives, technical solutions and advantages of the examples of the present invention clearer, the technical solutions in the examples of the present invention will be described with reference to the examples of the present invention clearly and completely. Obviously, the described examples are a portion of examples in the present invention instead of all the examples. Based on the examples of the present invention, all the other examples obtained by those skilled in the art without any inventive effort fall within the protection scope of the present invention.

[0043] Test materials, reagents and the like used in the following examples may be all commercially available, unless otherwise specified.

Comparative Example 1

[0044] A method for preparing a catalyst for synthesizing a cyclic carbonate, includes the following steps: [0045] 1) Under the protection of nitrogen, 1 mol o-phenylenediamine and 2 mol 3,5-di-tert-butyl salicylaldehyde were dissolved into 3 L methanol, 1 mol zinc acetate was added, and then 0.02 mol acetic acid was added as a catalyst, and heated for reflux reaction for 1 h at 80 C. [0046] 2) At the end of the reaction, the reaction system was cooled to room temperature, and methanol was removed via distillation under reduced pressure, and then the obtained product was dried and recrystallized in a hot acetonitrile to obtain the catalyst for synthesizing a cyclic carbonate.

[0047] The structure of the catalyst for synthesizing a cyclic carbonate is as follows:

##STR00007##

Example 1

[0048] A method for preparing a catalyst for synthesizing a cyclic carbonate, includes the following steps: [0049] 1) Under the protection of nitrogen, 1 mol o-phenylenediamine and 2 mol 3,5-di-tert-butyl salicylaldehyde were dissolved into 3 L methanol, 1 mol zinc acetate was added, and then 0.02 mol acetic acid was added as a catalyst, and heated for reflux reaction for 1 h at 80 C., and then 1 mol phenothiazine was added to continue the reaction for 1 h. [0050] 2) At the end of the reaction, the reaction system was cooled to room temperature, and methanol was removed via distillation under reduced pressure, and then the obtained product was dried and recrystallized in a hot acetonitrile to obtain the catalyst for synthesizing a cyclic carbonate.

[0051] The structure of the catalyst for synthesizing a cyclic carbonate is as follows:

##STR00008##

Example 2

[0052] A method for preparing a catalyst for synthesizing a cyclic carbonate, includes the following steps: [0053] 1) Under the protection of nitrogen, 1 mol o-phenylenediamine and 2 mol 3,5-dibromo-salicylaldehyde were dissolved into 3 L methanol, 1 mol zinc acetate was added, and then 0.001 mol formic acid was added as a catalyst, and heated for reflux reaction for 6 h at 50 C., and then 1.1 mol phenothiazine was added to continue the reaction for 6 h. [0054] 2) At the end of the reaction, the reaction system was cooled to room temperature, and ethanol was removed via distillation under reduced pressure, and then the obtained product was dried and recrystallized in a hot cyclohexane to obtain the catalyst for synthesizing a cyclic carbonate.

[0055] The structure of the catalyst for synthesizing a cyclic carbonate is as follows:

##STR00009##

Example 3

[0056] A method for preparing a catalyst for synthesizing a cyclic carbonate, includes the following steps: [0057] 1) Under the protection of nitrogen, 1 mol diphenylethylenediamine and 2 mol salicylaldehyde were dissolved into 3 L dichloromethane, 1 mol manganese acetate was added, and then 0.0001 mol oxalic acid was added as a catalyst, and heated for reflux reaction for 12 h at 20 C., and then 1 mol 2-(trifluoromethyl) phenothiazine was added to continue the reaction for 12 h. [0058] 2) At the end of the reaction, the reaction system was cooled to room temperature, and dichloromethane was removed via distillation under reduced pressure, and then the obtained product was dried and recrystallized in a hot acetonitrile to obtain the catalyst for synthesizing a cyclic carbonate.

[0059] The structure of the catalyst for synthesizing a cyclic carbonate is as follows:

##STR00010##

Example 4

[0060] A method for preparing a catalyst for synthesizing a cyclic carbonate, includes the following steps: [0061] 1) Under the protection of nitrogen, 1 mol 1,2-cyclohexanediamine and 2 mol 3,5-di-tert-butyl salicylaldehyde were dissolved into 3 L methanol, 1 mol zinc acetate was added, and then 0.003 mol oxalic acid was added as a catalyst, and heated for reflux reaction for 6 h at 50 C., and then 1.3 mol phenothiazine was added to continue the reaction for 6 h. [0062] 2) At the end of the reaction, the reaction system was cooled to room temperature, and methanol was removed via distillation under reduced pressure, and then the obtained product was dried and recrystallized in a hot acetonitrile to obtain the catalyst for synthesizing a cyclic carbonate.

[0063] The structure of the catalyst for synthesizing a cyclic carbonate is as follows:

##STR00011##

Example 5

[0064] A method for preparing a catalyst for synthesizing a cyclic carbonate, includes the following steps: [0065] 1) Under the protection of nitrogen, 1 mol ethylenediamine and 2 mol 3-fluoro-salicylaldehyde were dissolved into 3 L toluene, 1 mol nickel acetate was added, and then 0.005 mol benzoic acid was added as a catalyst, and heated for reflux reaction for 12 h at 60 C., and then 1.1 mol 2-acetyl phenothiazine was added to continue the reaction for 12 h. [0066] 2) At the end of the reaction, the reaction system was cooled to room temperature, and toluene was removed via distillation under reduced pressure, and then the obtained product was dried and recrystallized in a hot acetonitrile to obtain the catalyst for synthesizing a cyclic carbonate.

[0067] The structure of the catalyst for synthesizing a cyclic carbonate is as follows:

##STR00012##

Example 6

[0068] A method for preparing a catalyst for synthesizing a cyclic carbonate, includes the following steps: [0069] 1) Under the protection of nitrogen, 1 mol 4-bromo-o-phenylenediamine and 2 mol 3,5-di-tert-butyl salicylaldehyde were dissolved into 3 L acetone, 1 mol zinc acetate was added, and then 0.004 mol tartaric acid was added as a catalyst, and heated for reflux reaction for 12 h at 80 C., and then 1.5 mol 2-bromophenothiazine were added to continue the reaction for 12 h. [0070] 2) At the end of the reaction, the reaction system was cooled to room temperature, and acetone was removed via distillation under reduced pressure, and then the obtained product was dried and recrystallized in a hot acetonitrile to obtain the catalyst for synthesizing a cyclic carbonate.

[0071] The structure of the catalyst for synthesizing a cyclic carbonate is as follows:

##STR00013##

Example 7

[0072] A method for preparing a catalyst for synthesizing a cyclic carbonate, includes the following steps: [0073] 1) Under the protection of nitrogen, 1 mol 2,3-butanediamine and 2 mol 3-methyl-salicylaldehyde were dissolved into 3 L dichloromethane, 1 mol chromic chloride was added, and then 0.006 mol butanedioic acid was added as a catalyst, and heated for reflux reaction for 8 h at 70 C., and then 1 mol 4-chlorophenothiazine was added to continue the reaction for 8 h. [0074] 2) At the end of the reaction, the reaction system was cooled to room temperature, and dichloromethane was removed via distillation under reduced pressure, and then the obtained product was dried and recrystallized in a hot ethanol to obtain the catalyst for synthesizing a cyclic carbonate.

[0075] The structure of the catalyst for synthesizing a cyclic carbonate is as follows:

##STR00014##

Example 8

[0076] A method for preparing a catalyst for synthesizing a cyclic carbonate, includes the following steps: [0077] 1) Under the protection of nitrogen, 1 mol monophenyl ethylenediamine and 2 mol 3,5-di-tert-butyl salicylaldehyde were dissolved into 3 L methanol, 1 mol diethyl aluminum chloride was added, and then 0.002 mol propionic acid was added as a catalyst, and heated for reflux reaction for 10 h at 65 C., and then 1.1 mol azophenolthiazide was added to continue the reaction for 8 h. [0078] 2) At the end of the reaction, the reaction system was cooled to room temperature, and methanol was removed via distillation under reduced pressure, and then the obtained product was dried and recrystallized in a hot acetonitrile to obtain the catalyst for synthesizing a cyclic carbonate.

[0079] The structure of the catalyst for synthesizing a cyclic carbonate is as follows:

##STR00015##

Example 9

[0080] A method for preparing a catalyst for synthesizing a cyclic carbonate, includes the following steps: [0081] 1) Under the protection of nitrogen, 1 mol o-phenylenediamine and 2 mol 3,5-di-tert-butyl salicylaldehyde were dissolved into 3 L methanol, 1 mol ferric chloride was added, and then 0.001 mol formic acid was added as a catalyst, and heated for reflux reaction for 6 h at 70 C., and then 1 mol phenothiazine was added to continue the reaction for 6 h. [0082] 2) At the end of the reaction, the reaction system was cooled to room temperature, and methanol was removed via distillation under reduced pressure, and then the obtained product was dried and recrystallized in a hot acetonitrile to obtain the catalyst for synthesizing a cyclic carbonate.

[0083] The structure of the catalyst for synthesizing a cyclic carbonate is as follows:

##STR00016##

Example 10

[0084] A method for preparing a catalyst for synthesizing a cyclic carbonate, includes the following steps: [0085] 1) Under the protection of nitrogen, 1 mol 1,2-butanediamine and 2 mol 5-chloro-3-nitrosalicylaldehyde were dissolved into 3 L dimethylformamide, 1 mol cobalt acetate was added, and then 0.001 mol butyric acid was added as a catalyst, and heated for reflux reaction for 8 h at 70 C., and then 1 mol 2-methylthiophenothiazine was added to continue the reaction for 8 h. [0086] 2) At the end of the reaction, the reaction system was cooled to room temperature, and dimethylformamide was removed via distillation under reduced pressure, and then the obtained product was dried and recrystallized in a hot acetonitrile to obtain the catalyst for synthesizing a cyclic carbonate.

[0087] The structure of the catalyst for synthesizing a cyclic carbonate is as follows:

##STR00017##

Example 11

[0088] A method for preparing a catalyst for synthesizing a cyclic carbonate, includes the following steps: [0089] 1) Under the protection of nitrogen, 1 mol 1,2-propanediamine and 2 mol 3,5-dinitrosalicylaldehyde were dissolved into 3 L diethyl ether, 1 mol magnesium acetate was added, and then 0.01mol propionic acid was added as a catalyst, and heated for reflux reaction for 12 h at 65 C., and then 1 mol 2-chloro-7-hydroxyphenothiazine was added to continue the reaction for 12 h. [0090] 2) At the end of the reaction, the reaction system was cooled to room temperature, and diethyl ether was removed via distillation under reduced pressure, and then the obtained product was dried and recrystallized in a hot cyclohexane to obtain the catalyst for synthesizing a cyclic carbonate.

[0091] The structure of the catalyst for synthesizing a cyclic carbonate is as follows:

##STR00018##

Example 12

[0092] A method for preparing a catalyst for synthesizing a cyclic carbonate, includes the following steps: [0093] 1) Under the protection of nitrogen, 1 mol o-phenylenediamine and 2 mol 3,5-di-tert-butyl salicylaldehyde were dissolved into 3 L methanol, 1 mol calcium nitrate was added, and then 0.003 mol formic acid was added as a catalyst, and heated for reflux reaction for 2 h at 80 C., and then 1.4 mol phenothiazine was added to continue the reaction for 2 h. [0094] 2) At the end of the reaction, the reaction system was cooled to room temperature, and methanol was removed via distillation under reduced pressure, and then the obtained product was dried and recrystallized in a hot ethanol to obtain the catalyst for synthesizing a cyclic carbonate.

[0095] The structure of the catalyst for synthesizing a cyclic carbonate is as follows:

##STR00019##

Example 13

[0096] Provided is use of a catalyst for synthesizing a cyclic carbonate, in catalyzing carbon dioxide and an epoxide to synthesize a cyclic carbonate. The specific experimental process is as follows: [0097] 1. Performance test on the catalyst for synthesizing a cyclic carbonate:

[0098] The catalyst samples obtained in Examples 1-12 and Comparative Example 1 were subjected to the performance test on the catalyst for synthesizing a cyclic carbonate by the following method for evaluating performance of catalysts. The results are shown in Table 1.

[0099] 0.001 mol of the catalysts prepared in Examples 1-12 and Comparative Example 1 and 0.001 mol tetrabutylammonium bromide were added to a 1 L high pressure reactor with a mechanical stirring device and a temperature control heating device, respectively; air in the reactor was replaced by carbon dioxide, and after 400 g ethylene oxide was added, carbon dioxide was continuously introduced to maintain the pressure of the reaction system to be 1.0 MPa; the reaction system was stirred and heated up to 130 C., 3 h later after the reaction, stirring was stopped, and the reaction system was cooled to room temperature, and unreacted carbon dioxide was emptied, then the reaction liquid was isolated via distillation under reduced pressure to obtain the product ethylene carbonate. Qualitative analysis was conducted by GC-MS (HP6890/5973) and quantitative analysis was completed by GC (GC-112A).

TABLE-US-00001 TABLE 1 Catalytic performance of the different samples from each Example and Comparative Example to synthesize a cyclic carbonate Conversion Sample rate (%) Selectivity (%) Yield (%) Comparative 80.0 98.1 78.5 Example 1 Example 1 90.0 99.5 89.6 Example 2 95.0 99.5 94.5 Example 3 88.0 99.3 86.3 Example 4 83.0 99.4 82.5 Example 5 86.0 99.2 85.3 Example 6 97.0 99.5 96.5 Example 7 91.2 99.6 90.8 Example 8 81.0 99.3 80.4 Example 9 87.0 99.2 86.3 Example 10 82.1 99.5 81.6 Example 11 85.2 99.4 84.6 Example 12 84.3 99.2 83.6 [0100] 2. Repeatability test on the catalyst for synthesizing a cyclic carbonate

[0101] According to the catalytic experiment of the test sample, after the product cyclic carbonate was isolated by distillation under reduced pressure, the catalyst after reaction was collected; under the same test conditions, the samples in Example 1 and Comparative Example 1 were subjected to the repeatability test for 3 times. The test results are shown in Table 2.

TABLE-US-00002 TABLE 2 Repeatability of the different samples to synthesize a cyclic carbonate Conversion Sample rate (%) Selectivity (%) Yield (%) Comparative 80.0 98.1 78.5 Example 1 Comparative 78.2 98.1 76.7 Example 1 Repetition-1 Comparative 75.3 97.3 73.3 Example 1 Repetition-2 Comparative 70.1 96.8 67.9 Example 1 Repetition-3 Example 1 90.0 99.5 89.6 Example 1 89.9 99.5 89.5 Repetition-1 Example 1 90.1 99.4 89.6 Repetition-2 Example 1 90.0 99.5 89.6 Repetition-3

[0102] As can be seen from the comparison of test results of the samples between Example 1 and Comparative Example 1, compared to the sample in the comparative example not modified with phenothiazine, the sample in the phenothiazine-modified Example 1 has better catalyst activity and stability, and may be reused repeatedly; Moreover, after 3 cycles of the catalyst, the catalyst activity maintains about 90% and the selectivity maintains about 99.5%. This is mainly because the formulation of phenothiazine free radicals via the phenothiazine group and the central active metal may protect the central metal in the course of the reaction to avoid its inactivation due to self-polymerization and to enhance the stability of the catalyst, thereby improving the activity of the catalyst.

[0103] What is described in the above examples is convenient for those skilled in the art to understand and use the present invention. Those skilled in the art obviously can readily make various amendments to these examples, and can apply the general principle specified here to other examples without any inventive efforts. Therefore, the present invention is not limited to the above examples. According to the disclosure of the present invention, any improvement and amendment made by those skilled in the art not departing from the scope of the present invention shall fall within the protection scope of the present invention.