A method for preparing succinate

Abstract

This invention discloses a method for preparing succinate. The method includes the steps of reacting methyl acrylate with a lower alcohol in a catalytic system to obtain succinate; wherein the catalytic system includes a palladium compound, a quinoline derivative, and a phosphine ligand.

Description

Technical Field

[0001] This invention relates to compound synthesis, and more specifically to a method for the continuous production of succinate from syngas. Background Technology

[0002] Biodegradable PBS has excellent performance, but its synthetic monomer succinic acid is produced by traditional electrolysis or bio-fermentation methods, which are costly, have low production capacity, and are expensive, thus limiting the application of biodegradable PBS.

[0003] Producing succinic acid or its esters via non-petroleum routes aligns with my country's basic national conditions of "abundant coal, scarce oil, and limited gas," and is therefore receiving increasing attention in the field of succinic acid or its ester preparation. However, due to issues such as poor catalyst stability, the product yield is generally low.

[0004] Therefore, there is an urgent need in the field to provide a method for producing succinic acid or its esters that has high reactivity, stable catalyst activity, and high product yield. Summary of the Invention

[0005] The present invention aims to provide a method for producing succinic acid or its esters.

[0006] In a first aspect of the present invention, a method for preparing succinate is provided, the method comprising the steps of: reacting methyl acrylate with a low alcohol in a catalytic system to obtain succinate; wherein the catalytic system comprises a palladium compound, a quinoline derivative and a phosphine ligand.

[0007] In another embodiment, the catalytic system further contains an active agent, which is a cobalt-containing compound and / or a nickel-containing compound.

[0008] In another embodiment, the quinoline derivative is a compound with the structure shown in Formula I:

[0009]

[0010] in,

[0011] When R1 is -SO3H or -NO2, R2 is selected from hydrogen, halogen, -OH, -CN, -COOR4, -COR4, -C1-C6 alkyl, -C1-C6 alkoxy, -C2-C6 alkenyl, -C1-C6 alkynyl, -C5-C7 cycloalkyl or -C6-C7 aryl;

[0012] When R2 is -SO3H or -NO2, R1 is selected from hydrogen, halogen, -OH, -CN, -COOR4, -COR4, -C1-C6 alkyl, -C1-C6 alkoxy, -C2-C6 alkenyl, -C1-C6 alkynyl, -C5-C7 cycloalkyl or -C6-C7 aryl;

[0013] R3 is independently selected from hydrogen, halogen, -CN, -NO2, -COOR4, -COR4, -C1-C6 alkyl, -C2-C6 alkenyl, -C1-C6 alkynyl, -C5-C7 cycloalkyl or -C6-C7 aryl;

[0014] R4 is independently selected from hydrogen, -C1-C6 alkyl, -C2-C6 alkenyl, -C1-C6 alkynyl, or C6-C7 aryl.

[0015] In another embodiment, the quinoline derivative is selected from compounds with structures as shown in Formula 1, 2, 3, 4 or 5:

[0016]

[0017]

[0018] In another embodiment, the molar ratio of the active agent to the palladium compound is 0-50:1; preferably 0-1:1.

[0019] In another embodiment, the molar ratio of the quinoline derivative to the palladium compound is 1-10:1.

[0020] In another embodiment, the molar ratio of the phosphine ligand to the palladium compound is 2-100:1; preferably 2-20:1; more preferably 2-10:1.

[0021] In another embodiment, the phosphine ligand is selected from one or more of monodentate phosphine ligands, multidentate phosphine ligands, and chiral phosphine ligands; preferably, bidentate phosphine ligands with an oxanthracene or oxanthracene-like skeleton.

[0022] In another embodiment, carbon monoxide is introduced during the reaction to maintain a pressure of 1-5 MPa.

[0023] In another embodiment, the methyl acrylate is derived from methyl acrylate obtained by oxidizing propylene to produce acrylic acid and then esterifying it.

[0024] In a second aspect of the invention, a method for the continuous production of succinate is provided, the method comprising the steps of:

[0025] (1) React carbon monoxide and methanol to obtain acetic acid;

[0026] (2) Acetic acid and methanol are esterified to obtain methyl acetate;

[0027] (3) Methyl acetate and formaldehyde are subjected to an aldol condensation reaction to obtain methyl acrylate; and

[0028] (4) Methyl acrylate and a low alcohol are reacted with the method provided by the present invention as described above to obtain succinate.

[0029] In another embodiment, the carbon monoxide in step (1) comes from a gas containing carbon monoxide; preferably coal-based syngas.

[0030] Accordingly, the present invention provides a method for producing succinic acid or its esters with high reactivity, stable catalyst activity, and high product yield. Attached Figure Description

[0031] Figure 1 The GC-MS spectra of succinate obtained in the examples are shown; where 12.7 min is the internal standard, and 14.6 and 15.7 are succinate. Detailed Implementation

[0032] Through extensive and in-depth research, the inventors discovered a method for the continuous production of succinic acid or its esters from coal-based syngas using a specific catalytic system. Based on this, the present invention was completed.

[0033] Specifically, the present invention prepares succinic acid or its ester by the following steps;

[0034] The first step involves carbonylating carbon monoxide (CO) and methanol to prepare acetic acid.

[0035] The second step involves esterifying acetic acid and methanol to obtain methyl acetate.

[0036] The third step involves the aldol condensation reaction of methyl acetate and formaldehyde to obtain methyl acrylate.

[0037] The fourth step involves the carbonyl synthesis of succinate using methyl acrylate as a raw material.

[0038] The CO in the first step above can come from a CO-containing gas, with a CO content of 10-100 v / v% (e.g., but not limited to, 50-90 v / v%, 85-99 v / v%, 70-95 v / v%) based on the total volume of the CO-containing gas, and can be syngas, preferably coal-based syngas.

[0039] As used in this invention, "syngas" refers to a feedstock gas primarily composed of hydrogen and carbon monoxide, used for chemical synthesis. It is typically obtained by converting carbonaceous minerals such as coal, petroleum, natural gas, as well as coke oven gas, refinery gas, sludge, and biomass. "Coal-based syngas" refers to syngas obtained from coal, such as, but not limited to, syngas obtained from coal gas feedstocks such as pulverized coal syngas and coal-water slurry syngas.

[0040] In one embodiment of the present invention, in the presence of a conventional catalyst for the carbonylation of methanol to prepare acetic acid (e.g., but not limited to, iridium-ruthenium-based catalysts, rhodium-based catalysts, specifically such as iridium acetate, soluble iridium compounds such as H2IrCl6, soluble iridium complexes, etc.; soluble ruthenium complexes such as Ru(CO)4I2; rhodium trichloride, soluble rhodium complexes, etc.), methanol and CO are introduced into a stirredless reactor to carry out the carbonylation reaction; the reaction temperature is 180-220°C, and the pressure is 2.5-3.4 MPaG.

[0041] In one embodiment of the present invention, the second step described above involves an esterification reaction of the alcohol and the acetic acid obtained in the first step in the presence of a commonly used esterification catalyst (e.g., but not limited to, 98% sulfuric acid catalyst); the mass ratio of catalyst to acetic acid is 1:50-180, and the residence time is 2.2-2.5 hours.

[0042] In one embodiment of the present invention, in the third step, the methyl acetate obtained in the second step undergoes an aldol condensation reaction with formaldehyde in the presence of a commonly used aldol condensation catalyst (e.g., but not limited to, Cs-based catalysts, catalysts corresponding to Group IA or Group IIA metal elements, such as barium, specifically metal salts such as cesium acetate, cesium nitrate, and cesium carbonate). The molar ratio of methyl acetate to formaldehyde is 1-15:1, the reaction temperature is 300-400°C, and the feed space velocity is 0.2-10 h⁻¹. -1 .

[0043] In the second step described above, in addition to methanol, other C2-C4 alcohols, such as but not limited to ethanol, propanol, and butanol, can be used to obtain the corresponding acetate in the second step and the corresponding acrylate in the third step.

[0044] In one embodiment of the present invention, acrylates can also be obtained via a synthesis gas-propylene route, for example, CO → propylene → alkyl acrylate.

[0045] In the fourth step described above, the acrylate obtained in the third step is reacted with a lower alcohol in the presence of a catalytic system to obtain succinate; the catalytic system includes palladium compounds, quinoline derivatives and phosphine ligands; in one embodiment, the catalytic system further contains an active auxiliary agent.

[0046] As used in this invention, "succinate" refers to compounds with structures as shown in Formula V and / or Formula VI:

[0047]

[0048] R7 is selected from C1-C6 alkyl groups, such as, but not limited to, methyl, ethyl, propyl, butyl, etc.

[0049] As used in this invention, "palladium compound" refers to a compound containing the element palladium, such as, but not limited to, palladium dichloride, bis(acetonitrile)palladium dichloride, palladium acetate, bis(triphenylphosphine)palladium dichloride, (1,5-cyclooctadiene)palladium dichloride, allyl palladium chloride, tetratriphenylphosphine palladium, acetylacetone palladium, bis(dibenzylacetone)palladium, and tri(dibenzylacetone)palladium, etc.

[0050] The quinoline derivatives used in the catalytic system of the fourth step above are compounds with structures as shown in Formula I.

[0051] The specific quinoline compounds used in the fourth-step catalytic system mentioned above in this invention include:

[0052]

[0053] As used in this invention, "phosphine ligand" refers to a ligand containing phosphorus, including one or more of monodentate phosphine ligands, multidentate phosphine ligands, and chiral phosphine ligands; the monodentate phosphine ligands are, for example, but not limited to, one or more of trimethylphosphine, tributylphosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, triphenylphosphine, and tris(2-thienyl)phosphine; the multidentate phosphine ligands are, for example, but not limited to, one or more of 1,6-bis(diphenylphosphine)-hexane, (R,R")-2,2"-bis(diphenylphosphine)-1,1"-ferrocene, oxanthracene, or oxanthracene-like skeletons; preferably, monodentate phosphine ligands, oxanthracene, or oxanthracene-like skeletons are used.

[0054] The bidentate phosphine ligand structure of the oxanthracene or oxanthracene-like skeleton is shown in Formula II, Formula III or Formula IV:

[0055]

[0056] in,

[0057] R is independently selected from hydrogen, halogen, sulfonic acid group, carboxyl group, amino group, hydroxyl group, trifluoromethyl group, nitro group, substituted or unsubstituted -C1-C6 alkyl group, substituted or unsubstituted -C1-C6 alkoxy group, substituted or unsubstituted aryl group, phenoxy group, substituted or unsubstituted heterocyclic group.

[0058] R5 and R6 are selected from substituted or unsubstituted aryl groups, -C1-C5 alkyl groups, -C1-C5 alkoxy groups, and -C3-C6 alkyl groups, respectively. 15 cycloalkyl, substituted or unsubstituted -C7-C 15 arylalkyl groups;

[0059] R' is independently selected from hydrogen, substituted or unsubstituted aryl, -C1-C5 alkyl, -C3-C 15 cycloalkyl, substituted or unsubstituted -C7-C15 arylalkyl groups;

[0060] The groups that can be substituted include, but are not limited to, halogen, amino, hydroxy, carboxyl, and nitro groups.

[0061] The specific bidentate phosphine ligands with an oxanthracene or oxanthracene-like skeleton used in this invention include:

[0062]

[0063] The catalytic system used in the fourth step above may also contain cobalt-containing compounds and / or nickel-containing compounds as active auxiliaries.

[0064] As used in this invention, "cobalt-containing compound" refers to a compound containing the element cobalt, such as, but not limited to, cobalt nitrate; preferably a water-soluble cobalt salt, and the compound added at the same time does not produce a precipitate.

[0065] As used in this invention, "nickel-containing compound" refers to a compound containing nickel, such as, but not limited to, nickel nitrate; preferably a water-soluble nickel salt, and the compound added at the same time does not produce a precipitate.

[0066] In one embodiment of the present invention, the molar ratio of the active agent to the palladium compound in the catalytic system used in the fourth step above is 0-50:1; preferably 0-1:1.

[0067] In one embodiment of the present invention, the molar ratio of the quinoline derivative to the palladium compound in the catalytic system used in the fourth step above is 1-10:1. For example, but not limited to, 1.2-7:1, 2.5-5:1, etc.

[0068] In one embodiment of the present invention, the molar ratio of the phosphine ligand to the palladium compound in the catalytic system used in the fourth step above is 2-100:1; preferably 2-20:1; more preferably 2-10:1.

[0069] In the fourth step above, the low-carbon alcohol that reacts with methyl acrylate can be a C1-4 alcohol, such as, but not limited to, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, etc.

[0070] In one embodiment of the present invention, in the fourth step described above, the concentration of the catalytic system used is 0.0001-0.005M based on the volume of the low alcohol used, for example, but not limited to, 0.0005-0.001M, 0.0003-0.001M, 0.007-0.002M, 0.0012-0.003M, etc.

[0071] In one embodiment of the present invention, the fourth step is carried out in a high-pressure reactor. For example, but not limited to, the catalytic system, the low-carbon alcohol and the methyl acrylate obtained in the third step are added to the high-pressure reactor and mixed and reacted to obtain succinate. The amount of low-carbon alcohol is 50-250 ml, and the amount of methyl acrylate can be 5-100 mmol (for example, but not limited to, 10-50 mmol, 20-85 mmol, 35-70 mmol, etc.).

[0072] In one embodiment of the present invention, the fourth step described above is carried out in a high-pressure reactor. During the reaction, CO-containing gas is introduced into the reactor to maintain a pressure of 1-5 MPa, and the reaction is carried out for 2-10 hours at a temperature of 80-110°C (preferably 95-105°C). Preferably, CO-containing gas is continuously supplied to the reactor to keep the gas pressure inside the reactor constant. The CO content, based on the total volume of the CO-containing gas, is 10-100 v / v%, preferably syngas, and more preferably coal-based syngas.

[0073] In one embodiment of the present invention, in the fourth step, the catalytic system, the low-carbon alcohol, and the methyl acrylate obtained in the third step are added together to a high-pressure reactor and mixed. The air in the high-pressure reactor is replaced with nitrogen 2-4 times. Synthesis gas is introduced under continuous stirring to a pressure of 1-5 MPa, and the reaction is carried out for 2-10 hours. During the reaction, synthesis gas is continuously supplied to the reactor to keep the pressure of the synthesis gas in the reactor constant, thereby obtaining succinate.

[0074] The succinate ester prepared by the method of the present invention can be further prepared into succinic acid or butanediol by conventional methods in the art; for example, but not limited to, hydrolysis to prepare succinic acid, hydrogenation to prepare butanediol, etc.

[0075] In one embodiment of the present invention, succinate, a catalyst (acidic catalyst, such as concentrated sulfuric acid or a solid acid catalyst) and water are added to a reaction tower for catalytic hydrolysis to obtain succinic acid; in the presence of a Cu-based catalyst, hydrogen is reacted with succinate to produce butanediol.

[0076] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0077] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are used for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0078] The features mentioned above in this invention, or the features mentioned in the embodiments, can be combined arbitrarily. All features disclosed in this specification can be used with any compositional form, provided that the combination of these features does not contradict each other; all possible combinations should be considered within the scope of this specification. Each feature disclosed in the specification can be replaced by any alternative feature that provides the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the disclosed features are merely general examples of equivalent or similar features.

[0079] The main advantages of this invention are:

[0080] 1. This invention proposes a novel route for the continuous preparation of succinate from coal-based syngas for the first time.

[0081] 2. The quinoline derivatives used in this invention can improve the electronic cloud state and spatial distribution of palladium metal, and promote the dissociation and adsorption of acrylates on the catalyst surface; in addition, they can stabilize palladium and extend the catalyst lifetime; furthermore, they can increase the number of active vacancies and improve the activity of the catalyst. Under low pressure and low temperature, they can activate CO and acrylates to achieve high reactivity.

[0082] 3. The quinoline derivatives used in this invention can also synergistically interact with phosphine ligands, greatly improving the stability of acrylates and reducing side reactions such as polymerization and carbon deposition of acrylates, resulting in higher product yields at lower temperatures and pressures.

[0083] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise stated, all percentages, ratios, proportions, or parts are by weight. The units of weight-volume percentages in this invention are well known to those skilled in the art, for example, referring to the weight (grams) of solute in 100 ml of solution. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0084] The methyl acrylate used in the following examples was obtained through the following steps:

[0085] Step 1: Syngas-Acetic Acid (Acetic acid is prepared by carbonylation of syngas and methanol as raw materials)

[0086] In the presence of an iridium-ruthenium-based catalyst, methanol and CO (syngas with a CO content of 100 v / v%) are introduced into a stirredless reactor to carry out a carbonylation reaction; the reaction temperature is 180-220℃ and the pressure is 2.5-3.4 MPa.

[0087] Step 2: Acetic acid-methyl acetate (methyl acetate is prepared by esterification reaction using acetic acid obtained in Step 1 as raw material)

[0088] Methanol and acetic acid are esterified in the presence of 98% sulfuric acid catalyst; the mass ratio of catalyst to acetic acid is 1:50-180, and the residence time is 2.2-2.5 hours.

[0089] Step 3: Methyl acetate-methyl acrylate (Methyl acrylate is prepared using the methyl acetate obtained in Step 2 as a raw material)

[0090] In the presence of a Cs-based catalyst, methyl acetate and formaldehyde undergo an aldol condensation reaction to yield methyl acrylate; the molar ratio of methyl acetate to formaldehyde is 1-15:1, the reaction temperature is 300-400℃, and the feed space velocity is 0.2-10 h⁻¹. -1 .

[0091] The synthesis gas source used in the following examples is the same as that in step 1 above.

[0092] The gas chromatographic analysis method for detecting the reaction solution in the following examples is as follows:

[0093] The gas chromatograph is an Agilent 7890B. The chromatographic column is an Agilent DB-624 column.

[0094] The injection port temperature is 240℃, and the FID detector temperature is 260℃.

[0095] The column flow rate was 2 ml / min, the split ratio was 90:1, the column oven temperature was 55℃ for 3 min, the temperature was increased to 200℃ at 20℃ / min, and held for 3 min.

[0096] Product analysis methods: GC-MS: internal standard method, succinate and its byproducts were analyzed using an Agilent 7890B-Agilent 5977A instrument. MSD: column was an Agilent CP9103 VF-624ms.

[0097] Example 1

[0098] 0.03 mmol of palladium compound (palladium acetate), 0.05 mmol of 8-hydroxyquinoline-5-sulfonic acid, 0.08 mmol of triphenylphosphine, 200 mL of methanol, and 30 mmol of acrylate were added to a 500 mL high-pressure reactor. After purging the air three times with nitrogen, syngas was introduced to a pressure of 1.5 MPa and the reaction was carried out at 110 °C for 5 hours. During the reaction, syngas was continuously supplied to the reactor to maintain a constant pressure. The reaction solution was then analyzed by gas chromatography. The selectivity for dimethyl succinate was 99.5%, and the yield of dimethyl succinate was 80.7%.

[0099] See results Figure 1 .

[0100] Example 2

[0101] 0.03 mmol of palladium compound (bis(triphenylphosphine)palladium dichloride), 0.03 mmol of cobalt nitrate, 0.2 mmol of 8-hydroxyquinoline-5-sulfonic acid, 0.3 mmol of triphenylphosphine, 200 mL of methanol, and 45 mmol of acrylate were added to a 500 mL high-pressure reactor. After purging the reactor with nitrogen three times, syngas was introduced to a pressure of 1 MPa and the reaction was carried out at 95 °C for 6 hours. During the reaction, syngas was continuously supplied to the reactor to maintain a constant pressure. The reaction solution was then analyzed by gas chromatography. The selectivity for dimethyl succinate was 99.8%, and the yield of dimethyl succinate was 89.1%.

[0102] Example 3

[0103] 0.03 mmol of palladium compound (bis(triphenylphosphine)palladium dichloride), 0.01 mmol of nickel nitrate, 0.3 mmol of 8-nitroquinoline, 0.06 mmol of triphenylphosphine, 200 mL of methanol, and 30 mmol of acrylate were added to a 500 mL high-pressure reactor. After purging the air three times with nitrogen, syngas was introduced to a pressure of 3 MPa. The reaction was carried out for 5 hours at 105 °C. During the reaction, syngas was continuously supplied to the reactor to maintain a constant pressure. The reaction solution was analyzed by gas chromatography. The selectivity for dimethyl succinate was 99.5%, and the yield of dimethyl succinate was 75.6%.

[0104] Example 4

[0105] 0.03 mmol of palladium compound (bis(dibenzylacetone)palladium), 0.03 mmol of quinoline-8-sulfonic acid, 0.08 mmol of triphenylphosphine, 200 mL of methanol, and 15 mmol of acrylate were added to a 500 mL high-pressure reactor. After purging the air three times with nitrogen, syngas was introduced to a pressure of 1.5 MPa and the reaction was carried out at 100 °C for 2 hours. During the reaction, syngas was continuously supplied to the reactor to maintain a constant pressure. The reaction solution was then analyzed by gas chromatography. The selectivity for dimethyl succinate was 99.3%, and the yield of dimethyl succinate was 87.4%.

[0106] Example 5

[0107] 0.03 mmol of palladium compound (palladium acetate), 0.05 mmol of 8-ethoxyquinoline-5-sulfonic acid, 0.08 mmol of triphenylphosphine, 200 mL of methanol, and 30 mmol of acrylate were added to a 500 mL high-pressure reactor. After purging the air three times with nitrogen, syngas was introduced to a pressure of 1.5 MPa and the reaction was carried out at 80 °C for 5 hours. During the reaction, syngas was continuously supplied to the reactor to maintain a constant pressure. The reaction solution was then analyzed by gas chromatography. The selectivity for dimethyl succinate was 99.8%, and the yield of dimethyl succinate was 87.3%.

[0108] Example 6

[0109] 0.03 mmol of palladium compound (bis(triphenylphosphine)palladium dichloride), 0.03 mmol of cobalt nitrate, 0.2 mmol of 8-hydroxyquinoline-5-sulfonic acid, 0.3 mmol of L1, 200 mL of methanol, and 45 mmol of acrylate were added to a 500 mL high-pressure reactor. After purging the air three times with nitrogen, syngas was introduced to a pressure of 1 MPa and the reaction was carried out at 100 °C for 6 hours. During the reaction, syngas was continuously supplied to the reactor to maintain a constant pressure. The reaction solution was then analyzed by gas chromatography. The selectivity for dimethyl succinate was 99.6%, and the yield of dimethyl succinate was 89.9%.

[0110] Example 7

[0111] 0.03 mmol of palladium compound (palladium acetate), 0.01 mmol of nickel nitrate, 0.1 mmol of quinoline-8-sulfonic acid, 0.3 mmol of L2, 200 mL of methanol, and 30 mmol of acrylate were added to a 500 mL high-pressure reactor. After purging the air three times with nitrogen, syngas was introduced to a pressure of 2 MPa and the reaction was carried out at 100 °C for 6 hours. During the reaction, syngas was continuously supplied to the reactor to maintain a constant pressure. The reaction solution was then analyzed by gas chromatography. The selectivity for dimethyl succinate was 99.8%, and the yield of dimethyl succinate was 87.5%.

[0112] Example 8

[0113] 0.03 mmol of palladium compound (bis(triphenylphosphine)palladium dichloride), 0.01 mmol of cobalt nitrate, 0.1 mmol of 2-methyl-8-nitroquinoline, 0.3 mmol of L4, 200 mL of methanol, and 40 mmol of acrylate were added to a 500 mL high-pressure reactor. After purging the air three times with nitrogen, syngas was introduced to a pressure of 3 MPa. The reaction was carried out for 6 hours at 100 °C. During the reaction, syngas was continuously supplied to the reactor to maintain a constant pressure. The reaction solution was analyzed by gas chromatography. The selectivity for dimethyl succinate was 99.5%, and the yield of dimethyl succinate was 89.5%.

[0114] Example 9

[0115] 0.03 mmol of palladium compound (bis(dibenzylacetone)palladium), 0.2 mmol of 8-hydroxyquinoline-5-sulfonic acid, 0.3 mmol of L7, 200 mL of methanol, and 45 mmol of acrylate were added to a 500 mL high-pressure reactor. After purging the air three times with nitrogen, syngas was introduced to a pressure of 2 MPa and the reaction was carried out at 100 °C for 6 hours. During the reaction, syngas was continuously supplied to the reactor to maintain a constant pressure. The reaction solution was then analyzed by gas chromatography. The selectivity for dimethyl succinate was 97.8%, and the yield of dimethyl succinate was 87.4%.

[0116] The results of Examples 1-9 show that, in a reactor, the TON can reach 80,000 succinate / molar palladium for up to 300 hours.

[0117] Examples 10-12

[0118] By replacing methanol in Examples 1-5 with ethanol, propanol or butanol, diethyl succinate, dipropyl succinate and dibutyl succinate were obtained, respectively.

[0119] Comparative Example 1

[0120] The method of Example 2 was followed, except that 8-hydroxyquinoline-5-sulfonic acid was replaced with 0.2 mmol of methanesulfonic acid. The resulting selectivity for succinate was 64.0%, and the yield of succinate was 62.2%. The catalyst could be continuously used in the reactor for 100 h at a TON of 40,000 succinate / molar palladium.

[0121] Comparative Example 2

[0122] The method of Example 6 was followed, except that 8-hydroxyquinoline-5-sulfonic acid was replaced with 0.2 mmol of p-toluenesulfonic acid. The selectivity for succinate was 68.9%, and the yield of succinate was 54.3%. The catalyst could be kept in the reactor for 100 h at a TON of 37,000 / mol palladium.

[0123] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the substantive technical content of the present invention. The substantive technical content of the present invention is broadly defined within the scope of the claims. Any technical entity or method completed by others that is completely identical to or an equivalent modification of the claims is considered to be covered within the scope of the claims.

Claims

1. A process for the preparation of a succinate ester, characterized in that, The method comprises the steps of: reacting methyl acrylate with low carbon alcohol under a catalytic system to obtain succinate; the catalytic system comprises a palladium compound, a quinoline derivative and a phosphine ligand; the catalytic system further comprises an active assistant, the active assistant is a cobalt-containing compound and / or a nickel-containing compound; carbon monoxide is introduced during the reaction to make the pressure be 1-5 MPa; The quinoline derivative is a compound as shown in formula I: Wherein, When R1 is -SO3H or -NO2, R2 is selected from hydrogen, halogen, -OH, -CN, -COOR4, -COR4, -C1-C6 alkyl, -C1-C6 alkoxy, -C2-C6 alkenyl, -C2-C6 alkynyl, -C5-C7 cycloalkyl or -C6-C7 aryl; When R2 is -SO3H or -NO2, R1 is selected from hydrogen, halogen, -OH, -CN, -COOR4, -COR4, -C1-C6 alkyl, -C1-C6 alkoxy, -C2-C6 alkenyl, -C2-C6 alkynyl, -C5-C7 cycloalkyl or -C6-C7 aryl; R3 is independently selected from hydrogen, halogen, -CN, -NO2, -COOR4, -COR4, -C1-C6 alkyl, -C2-C6 alkenyl, -C2-C6 alkynyl, -C5-C7 cycloalkyl or -C6-C7 aryl; R4 is independently selected from hydrogen, -C1-C6 alkyl, -C2-C6 alkenyl, -C2-C6 alkynyl or C6-C7 aryl; The cobalt-containing compound is a water-soluble cobalt salt, and the simultaneously added compound does not produce precipitation; the nickel-containing compound is a water-soluble nickel salt, and the simultaneously added compound does not produce precipitation.

2. The production method according to claim 1, wherein The quinoline derivative is selected from compounds as shown in formula 1, 2, 3, 4 or 5:

3. The production method according to claim 1, wherein The molar ratio of the active assistant to the palladium compound is (1 / 3-50):

1.

4. The production method according to claim 3, wherein The molar ratio of the active assistant to the palladium compound is (1 / 3-1):

1.

5. The production method according to claim 1, wherein The molar ratio of the quinoline derivative to the palladium compound is (1-10):

1.

6. The production method according to claim 1, wherein The molar ratio of the phosphine ligand to the palladium compound is (2-100):

1.

7. The production method according to claim 6, wherein The molar ratio of the phosphine ligand to the palladium compound is (2-20):

1.

8. The production method according to claim 7, wherein The molar ratio of the phosphine ligand to the palladium compound is (2-10):

1.

9. The production method according to claim 1, wherein The phosphine ligand is selected from one or more of monodentate phosphine ligand, polydentate phosphine ligand and chiral phosphine ligand.

10. The production method according to claim 9, wherein The phosphine ligand is selected from a bidentate phosphine ligand with a xanthene or xanthene-like skeleton.

11. The production method according to claim 1, wherein The cobalt-containing compound is cobalt nitrate.

12. The production method according to claim 1, wherein The nickel-containing compound is nickel nitrate.

13. The production method according to claim 1, wherein The low carbon alcohol reacted with methyl acrylate is C1-4 alcohol.

14. The production method according to claim 1, wherein The concentration of the catalytic system is 0.0001-0.005 M in terms of the volume of the used low carbon alcohol.

15. A method for continuous production of succinate ester, characterized by, The method comprises the steps of: (1) reacting carbon monoxide and methanol to obtain acetic acid; (2) esterifying acetic acid and methanol to obtain methyl acetate; (3) subjecting methyl acetate and formaldehyde to aldol condensation to obtain methyl acrylate; (4) subjecting methyl acrylate to low carbon alcohol by the method as claimed in any one of claims 1-14 to obtain succinate.

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