Method for preparing dicarboxylic ester through palladium-double ligand tandem catalysis of carbonylation of 1, 3-conjugated diene

Abstract

The invention provides a method for preparing dicarboxylate by palladium-double ligand tandem catalysis of carbonylation of 1, 3-conjugated diene, and the method comprises the following steps: adding 1, 3-conjugated diene into a reaction solution containing a palladium cation source, a first ligand monodentate phosphine ligand L1, a second ligand bidentate phosphine ligand L2, an anion source and alcohol, then adding a carbonyl source, and reacting to obtain the dicarboxylate. The dicarboxylic acid ester is obtained. According to the invention, a tandem catalysis strategy is adopted, two ligands of monodentate phosphine and bidentate phosphine are introduced at the same time, a palladium catalysis tandem system is constructed, the dicarboxylate is directly prepared from 1, 3-conjugated diene by a one-pot method, the dosage of the expensive bidentate phosphine ligand is effectively reduced under the same catalysis efficiency, and the use of organic strong acid as an auxiliary agent can be avoided; and the requirement on the material of the reactor is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalytic synthesis of compounds, and relates to a method for preparing dicarboxylic acid esters by palladium-bidentate ligand tandem catalyzed carbonylation of 1,3-conjugated dienes. Background Art

[0002] Dienes with conjugated double bond structures, especially by-products of naphtha steam cracking such as 1,3-butadiene and isoprene, have important application values in industrial processes. Among them, the polymer industry consumes most of the conjugated dienes. In addition, the high-value utilization of conjugated dienes by homogeneous transition metal catalysis has broad application prospects. For example, by introducing various functional groups such as amines, esters, aldehydes or alcohols, conjugated dienes can be selectively converted into fine chemicals for the production of high-value-added products such as fragrances, nylons and pharmaceuticals.

[0003] Among them, the preparation of dicarboxylic acid esters by conjugated diene carbonylation reaction refers to the reaction of conjugated dienes with carbon monoxide and alcohols to undergo two carbonylation reactions under the action of a catalyst to generate dicarboxylic acid esters. For example, 1,3-butadiene undergoes a carbonylation reaction with carbon monoxide and methanol to prepare dimethyl adipate. The above reaction process is extremely challenging and requires the establishment of an efficient and cooperative catalytic system to ensure: (1) the first carbonylation carbonyl insertion occurs at the terminal carbon of 1,3-butadiene; (2) the double bond in the intermediate of the first carbonylation isomerizes to the other terminal; (3) the second carbonylation carbonyl inserts into the terminal carbon. In early reports, the above reaction was carried out in two steps, namely: 1,3-butadiene was converted into methyl 3-pentenoate through a carbonylation reaction, and then methyl 3-pentenoate was converted into dimethyl adipate in another independent reactor (Xianjie Fang, et.al. Palladium-Catalyzed Alkoxycarbonylation of Conjugated Dienes under Acid-Free Conditions: Atom-Economic Synthesis of β,γ-Unsaturated Esters. Angew.Chem.Int.Ed. 2014, 53: 9030–9034). The regioselectivity of both steps of the reaction was achieved by using a sterically hindered bidentate phosphine ligand for regulation, but the catalytic systems (palladium metal salts, cocatalysts, solvents) and operating conditions (temperature, pressure, time, etc.) were not the same. Recently, there has been a breakthrough in the direct preparation of dicarboxylic acid esters by the carbonylation of 1,3-conjugated dienes in a single reactor. CN201710585530 discloses a method for preparing di- or tricarboxylic acid esters by the alkoxycarbonylation of a diene with conjugated double bonds. This method uses a palladium-xanthene-based bisphosphine ligand to catalyze the alkoxycarbonylation of 1,3-butadiene derivatives with carbon monoxide and organic alcohols to prepare diesters or triesters. Subsequently, the Beller group developed a pyridine-substituted bidentate phosphine ligand (HeMaRaphos). After palladium was coordinated with the above ligand in a molar ratio of 1:2, it catalyzed the carbonylation reaction of 1,3-butadiene with carbon monoxide and n-butanol, and directly produced dibutyl adipate with a yield of 85% and a linear selectivity of 97% (Ji Yang, et.al., Matthias Beller Direct synthesis of adipic acid esters via palladium-catalyzed carbonylation of 1,3-dienes. Science 2019, 366: 1514–1517).Further experiments have shown that a catalytic system with a molar ratio of palladium to the bidentate phosphine ligand dtbpx of 1:2 can also promote this transformation (Ji Yanga, et al., Efficient Palladium-catalyzed Carbonylation of 1,3-Dienes: Selective Synthesis of Adipates and Other Aliphatic Diesters. Angew. Chem. Int. Ed. 2021, 60: 9527–9533), giving the corresponding diester in 80% yield and 97% selectivity, but with much worse time efficiency. In the above studies, a single bidentate phosphine ligand was used, and the molar ratio of palladium to the bidentate phosphine ligand in the feed was 1:2. The amount of the bidentate phosphine ligand used was large, requiring multiple steps of precise synthesis, which was expensive, and some of them had not yet formed commercial capabilities. In addition, an organic strong acid such as p-toluenesulfonic acid had to be added as a cocatalyst during the reaction, which required high corrosion resistance of the equipment. At the same time, there was still much room for improvement in catalytic activity, especially time efficiency. SUMMARY OF THE INVENTION

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a method for preparing dicarboxylic acid esters by palladium-bidentate ligand tandem catalyzed carbonylation of 1,3-conjugated dienes.

[0005] To achieve this purpose, the present invention adopts the following technical solutions:

[0006] On the one hand, the present invention provides a method for preparing dicarboxylic acid esters by palladium-bidentate ligand tandem catalyzed carbonylation of 1,3-conjugated dienes, and the method comprises the following steps:

[0007] Adding 1,3-conjugated diene to a reaction solution containing a palladium cation source, a first ligand monodentate phosphine ligand L1, a second ligand bidentate phosphine ligand L2, an anion source and an alcohol, and then adding a carbonyl source and reacting to obtain the dicarboxylic acid ester.

[0008] In the present invention, a tandem catalysis strategy is adopted. By simultaneously introducing two types of ligands, monodentate and bidentate phosphines, a palladium-catalyzed tandem system is constructed to directly prepare dicarboxylic acid esters from 1,3-conjugated dienes in one pot, effectively reducing the amount of expensive bidentate phosphine ligands under the same catalytic efficiency. At the same time, the above system can avoid using organic strong acids as additives, reducing the requirements for the reactor material.

[0009] In the present invention, the diester is directly prepared by the synergistic action of the palladium cation source with the monodentate phosphine ligand L1 and the bidentate phosphine ligand L2 in one step, reducing the catalyst cost and equipment investment.

[0010] Preferably, the palladium cation source includes palladium dichloride (PdCl 2) Palladium(II) bromide (PdBr 2 ) Palladium(II) iodide (PdI 2 ) Palladium(II) acetate (Pd(OAc) 2 ) Bis(acetonitrile)palladium(II) dichloride (Pd(CH 3 CN) 2 Cl 2 ) (1,5-Cyclooctadiene)palladium(II) dichloride (Pd(cod)Cl 2 ) Palladium(II) acetylacetonate (Pd(acac) 2 ) Palladium(II) trifluoroacetate (Pd(TFA) 2 ) Palladium(II) pivalate (Pd(CH 3 CO 2 ) 2 ) Tris(dibenzylideneacetone)dipalladium(0) (Pd 2 (dba) 3 ) and bis(dibenzylideneacetone)palladium(0) (Pd 2 (dba) 2 ) or a combination of any one or at least two of them.

[0011] Preferably, the first ligand, the monodentate phosphine ligand L1, is a compound having the structure of formula (I):

[0012]

[0013] Wherein, R 1 , R 2 and R 3 are independently selected from substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, substituted or unsubstituted C3-C8 cycloalkyl, substituted or unsubstituted C6-C18 aryl, substituted or unsubstituted C5-C18 heteroaryl, and substituted or unsubstituted C6-C18 aryloxy.

[0014] Preferably, the substituents in the substituted groups are selected from halogen, C1-C6 alkyl, C1-C6 haloalkyl or C1-C6 alkoxy.

[0015] In the present invention, the C1-C6 can be C1, C2, C3, C4, C5 or C6; the C3-C8 can be C3, C4, C5, C6, C7 or C8, the C6-C18 can be C6, C7, C8, C9, C10, C12, C14, C16 or C18, and the C5-C18 can be C5, C6, C7, C8, C9, C10, C12, C14, C16 or C18.

[0016] Preferably, the substituents in the substituted groups are selected from F, methyl, methoxy, ethoxy or trifluoromethyl.

[0017] Preferably, the R 1 , R 2 and R 3 are independently selected from methyl, n-butyl, tert-butyl, cyclohexyl, methoxy, ethoxy, phenyl, benzyl, phenoxy, benzyloxy, n-butoxy, isopropoxy, methylphenyl, methoxyphenyl, fluorophenyl or trifluoromethylphenyl.

[0018] Preferably, the first ligand, the monodentate phosphine ligand L1, is any one of the following compounds:

[0019]

[0020]

[0021] Preferably, the second ligand, the bidentate phosphine ligand L2, is a compound having the structure of formula (II):

[0022]

[0023] wherein R is selected from or n is an integer from 1 to 6 (such as 1, 2, 3, 4, 5 or 6); R' is selected from phenyl, cyclohexyl or tert-butyl, or two R' and the P to which they are attached form the following ring structure:

[0024] Preferably, the second ligand, the bidentate phosphine ligand L2, is any one of the following compounds:

[0025]

[0026]

[0027] wherein R 4 and R 5 are selected from phenyl, cyclohexyl or tert-butyl, n is an integer from 1 to 6 (such as 1, 2, 3, 4, 5 or 6); Ph represents phenyl and tBu represents tert-butyl.

[0028] In the palladium-bidentate phosphine ligand system for catalyzing the carbonylation reaction of 1,3-conjugated dienes reported so far, an organic strong acid needs to be added as an auxiliary agent. Since the introduction of the organic strong acid will cause rapid alkylation of the monodentate phosphine ligand, resulting in phosphine loss, while the present invention does not need to use an organic strong acid, but uses an anion source, avoiding the phosphine loss caused by the introduction of organic acids, also avoiding the corrosion of equipment, reducing costs, improving the ligand utilization rate and reducing its dosage.

[0029] Preferably, the anion source is selected from any one or a combination of at least two of boric acid, phenylboronic acid, p-tert-butylphenylboronic acid, p-methoxyphenylboronic acid, p-methylphenylboronic acid, p-fluorophenylboronic acid, p-trifluoromethylphenylboronic acid, 5-chlorosalicylic acid / boric acid, 4-vinylphenylboronic acid, bis(pinacolato)diboron or allyl(pinacolato)borane.

[0030] Preferably, the alcohol is selected from C1-C20 alcohols. The alcohol can be, for example, linear, branched, cycloaliphatic or cyclic. The alcohol can also contain unsaturated or aromatic groups.

[0031] Preferably, the alcohol is selected from any one or a combination of at least two of methanol, ethanol, 1-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, benzyl alcohol or phenethyl alcohol;

[0032] Preferably, the reaction solvent in the reaction solution is selected from any one or a combination of at least two of alkane solvents, aromatic solvents, ether solvents or amide solvents.

[0033] Preferably, the reaction solvent is selected from any one or a combination of at least two of n-heptane, toluene, xylene, anisole, diphenyl ether, dichloromethane, 1,2-dichloroethane, N,N-dimethylformamide or N-methylpyrrolidone.

[0034] Preferably, the 1,3-conjugated diene contains 4 to 30 (such as 4, 5, 6, 7, 8, 9, 10, 13, 15, 18, 20, 22, 25, 28 or 30, etc.) carbon atoms and has the structure shown in the following formula (III):

[0035]

[0036] In formula (III), R 3 , R 4 , R 5 and R 6 are independently selected from hydrogen, C1-C12 (such as C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11 or C12) alkyl, C2-C12 (such as C2, C3, C4, C5, C6, C7, C8, C9, C10, C11 or C12) alkenyl, C2-C12 (such as C2, C3, C4, C5, C6, C7, C8, C9, C10, C11 or C12) alkynyl or C6-C20 (such as C5, C6, C7, C8, C9, C10, C12, C14, C16, C18 or C20, etc.) aryl.

[0037] The 1,3-conjugated diene as described above may be substituted by one or more alkyl, alkenyl, alkynyl or aryl groups. The diene may also contain more than two double bonds, two of which must be conjugated.

[0038] Preferably, the 1,3-conjugated diene is selected from any one or a combination of at least two of 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2,4-dimethyl-1,3-pentadiene, 7-methyl-3-methylene-1,6-octadiene (i.e., myrcene) or 2-phenyl-1,3-butadiene.

[0039] Preferably, the carbonyl source is selected from carbon monoxide.

[0040] Preferably, the molar ratio of the palladium cation source, the monodentate phosphine ligand and the bidentate phosphine ligand is 1:1-2:0.25-0.75. For example, when the number of moles of the palladium cation source is 1, the number of moles of the monodentate phosphine ligand can be 1, 1.1, 1.4, 1.6, 1.8 or 2, and the number of moles of the bidentate phosphine ligand can be 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7 or 0.75.

[0041] Preferably, the molar ratio of the 1,3-conjugated diene to the palladium cation source is 1:0.005-0.02, such as 1:0.005, 1:0.008, 1:0.01, 1:0.012, 1:0.015, 1:0.018 or 1:0.02.

[0042] Preferably, the molar ratio of the 1,3-conjugated diene to the anion source is 1:0.05-0.20, such as 1:0.05, 1:0.08, 1:0.1, 1:0.13, 1:0.15, 1:0.18 or 1:0.20.

[0043] Preferably, the molar ratio of the 1,3-conjugated diene to the alcohol is 1:2-4, such as 1:2, 1:2.3, 1:2.5, 1:2.8, 1:3, 1:3.5, 1:3.8 or 1:4.

[0044] Preferably, the molar ratio of the 1,3-conjugated diene to the reaction solvent in the reaction solution is 1:9-19, such as 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:178, 1:18 or 1:19.

[0045] Preferably, after adding the carbonyl source, the pressure in the reaction system is 10 - 60 bar, such as 10 bar, 15 bar, 20 bar, 25 bar, 30 bar, 35 bar, 40 bar, 45 bar, 50 bar, 55 bar or 60 bar.

[0046] Preferably, the temperature of the reaction is 100 - 140 °C, such as 100 °C, 110 °C, 115 °C, 120 °C, 125 °C, 130 °C, 135 °C or 140 °C.

[0047] Preferably, the reaction time is 1 - 24 h, such as 1 h, 3 h, 5 h, 8 h, 10 h, 13 h, 15 h, 18 h, 20 h, 22 h or 24 h.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] In the present invention, a tandem catalysis strategy is adopted. By simultaneously introducing two types of ligands, monodentate and bidentate phosphines, a palladium-catalyzed tandem system is constructed to directly prepare dicarboxylic acid esters from 1,3-conjugated dienes in one pot, effectively reducing the amount of expensive bidentate phosphine ligands under the same catalytic efficiency. At the same time, the above system can avoid using strong organic acids as additives, reducing the requirements for the reactor material. Detailed implementation manners

[0050] The technical solutions of the present invention will be further described below through specific implementation manners. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be construed as specific limitations of the present invention.

[0051] Examples 1 - 5

[0052] Charge a 4 mL sample bottle with a palladium cation source (0.02 mmol, 0.02 eq.), triphenylphosphine (0.02 mmol, 0.02 eq.), 1,2-bis(diadamantylphosphinomethyl)benzene (0.01 mmol, 0.01 eq.), phenylboronic acid (0.08 mmol, 0.08 eq.), methanol (2.2 mmol, 2.2 eq.), toluene (1 mL) and a magnetic stir bar. Seal the container with a special aluminum cap and septum. Inject a 20% by mass 1,3-butadiene toluene solution (1 mmol, 1 eq.) with a syringe, and fix the sample bottle on a metal module. Transfer it to a 30 mL high-pressure reaction kettle under an argon stream. Replace the atmosphere in the kettle with 40 bar of carbon monoxide, add the internal standard mesitylene (0.5 mmol, 0.5 eq.), react at 120 °C for 24 h, and use GC (Agilent 7890A) for analysis and detection of the yield and selectivity of dimethyl adipate. The results are shown in Table 1.

[0053] Table 1

[0054] Example Palladium cation source Dimethyl adipate yield Selectivity 1 <![CDATA[PdCl 2 > 53％ 74％ 2 <![CDATA[Pd(OAc) 2 > 0％ 0％ 3 <![CDATA[Pd(CH 3 CN) 2 Cl 2 > 57％ 77％ 4 <![CDATA[Pd(cod)Cl 2 > 62％ 81％ 5 <![CDATA[Pd(acac) 2 > 46％ 63％

[0055] Examples 6 - 13

[0056] Charge Pd(cod)Cl into a 4 mL sample vial 2 (0.02 mmol, 0.02 eq.), monodentate phosphine ligand L1 (0.02 mmol, 0.02 eq.), 1,2 - bis(diadamantylphosphinomethyl)benzene (0.01 mmol, 0.01 eq.), phenylboronic acid (0.08 mmol, 0.08 eq.), methanol (2.2 mmol, 2.2 eq.), toluene (1 mL) and a magnetic stir bar. Seal the container with a special aluminum cap and septum. Inject a 20% by mass 1,3 - butadiene toluene solution (1 mmol, 1 eq.) using a syringe, and fix the sample vial on a metal module. Transfer it to a 30 mL high - pressure reactor under an argon stream. Replace the atmosphere in the reactor with 40 bar of carbon monoxide, add internal standard mesitylene (0.5 mmol, 0.5 eq.) and react at 120 °C for 24 h. Use GC for analysis to detect the yield and selectivity of dimethyl adipate. The results are shown in Table 2.

[0057] Table 2

[0058]

[0059]

[0060]

[0061] Examples 14 to 16

[0062] Charge Pd(cod)Cl into a 4 mL sample vial 2 (0.02 mmol, 0.02 eq.), tris(o - tolyl)phosphine (0.02 mmol, 0.02 eq.), bidentate phosphine ligand L2 (0.01 mmol, 0.01 eq.), phenylboronic acid (0.08 mmol, 0.08 eq.), methanol (2.2 mmol, 2.2 eq.), toluene (1 mL) and a magnetic stir bar. Seal the container with a special aluminum cap and septum. Inject a 20% by mass 1,3 - butadiene toluene solution (1 mmol, 1 eq.) using a syringe, and fix the sample vial on a metal module. Transfer it to a 30 mL high - pressure reactor under an argon stream. Replace the atmosphere in the reactor with 40 bar of carbon monoxide, add internal standard mesitylene (0.5 mmol, 0.5 eq.) and react at 120 °C for 24 h. Use GC for analysis to detect the yield and selectivity of dimethyl adipate. The test results are shown in Table 3.

[0063] Table 3

[0064]

[0065] Examples 17 - 19

[0066] Charge Pd(cod)Cl into a 4 mL sample vial 2 (0.02 mmol, 0.02 eq.), tris(ortho - tolyl)phosphine (0.02 mmol, 0.02 eq.), 1,2 - bis(4 - phosphonato ketone)xylene (0.01 mmol, 0.01 eq.), anion source (0.08 - 0.2 mmol, 0.08 - 0.2 eq.), methanol (2.2 mmol, 2.2 eq.), toluene (1 mL) and a magnetic stir bar. Seal the container with a special aluminum cap and septum. Inject a 20% by mass 1,3 - butadiene toluene solution (1 mmol, 1 eq.) with a syringe, fix the sample vial on a metal module, and transfer it to a 30 mL high - pressure reactor under an argon stream. Replace the atmosphere in the reactor with 40 bar of carbon monoxide, add internal standard mesitylene (0.5 mmol, 0.5 eq.), react at 120 °C for 24 h, and use GC for analysis to detect the yield and selectivity of dimethyl adipate. The results are shown in Table 4.

[0067] Table 4

[0068]

[0069] Examples 20 to 22

[0070] Charge Pd(cod)Cl into a 4 mL sample vial 2 (0.02 mmol, 0.02 eq.), tris(ortho - tolyl)phosphine (0.02 mmol, 0.02 eq.), 1,2 - bis(4 - phosphonato ketone)xylene (0.01 mmol, 0.01 eq.), 5 - chlorosalicylic acid (0.2 mmol, 0.2 eq.), boric acid (0.1 mmol, 0.1 eq.), methanol (2.2 mmol, 2.2 eq.), reaction solvent (1 mL) and a magnetic stir bar. Seal the container with a special aluminum cap and septum. Inject a 20% by mass 1,3 - butadiene toluene solution (1 mmol, 1 eq.) with a syringe, fix the sample vial on a metal module, and transfer it to a 30 mL high - pressure reactor under an argon stream. Replace the atmosphere in the reactor with 40 bar of carbon monoxide, add internal standard mesitylene (0.5 mmol, 0.5 eq.), react at 120 °C for 24 h, and use GC for analysis to detect the yield and selectivity of dimethyl adipate. The results are shown in Table 5.

[0071] Table 5

[0072]

[0073] Examples 23 to 26

[0074] Charge a 4 mL sample vial with Pd(cod)Cl 2 (0.02 mmol, 0.02 eq.), tris(o -tolyl)phosphine (0.02 mmol, 0.02 eq.), 1,2 -bis(4 -phosphonato ketone)xylene (0.01 mmol, 0.01 eq.), 5 -chlorosalicylic acid (0.2 mmol, 0.2 eq.), boric acid (0.1 mmol, 0.1 eq.), alcohol (2.2 mmol, 2.2 eq.), toluene (1 mL) and a magnetic stir bar. Seal the container with a special aluminum cap and septum. Inject a 20 wt% 1,3 -butadiene toluene solution (1 mmol, 1 eq.) using a syringe, and fix the sample vial on a metal module. Transfer it to a 30 mL high -pressure reactor under an argon stream. Replace the atmosphere in the reactor with 40 bar of carbon monoxide, add the internal standard mesitylene (0.5 mmol, 0.5 eq.) and react at 120 °C for 24 h. Use column chromatography to obtain the isolated yield and selectivity of the main product from the reaction mixture. The results are shown in Table 6 below.

[0075] Table 6

[0076]

[0077]

[0078] Examples 27 to 30

[0079] Charge a 4 mL sample vial with Pd(cod)Cl 2 (0.02 mmol, 0.02 eq.), tris(o -tolyl)phosphine (0.02 mmol, 0.02 eq.), 1,2 -bis(4 -phosphonato ketone)xylene (0.01 mmol, 0.01 eq.), 5 -chlorosalicylic acid (0.2 mmol, 0.2 eq.), boric acid (0.1 mmol, 0.1 eq.), methanol (2.2 mmol, 2.2 eq.), toluene (1 mL) and a magnetic stir bar. Seal the container with a special aluminum cap and septum. Inject 1,3 -conjugated diene (1 mmol, 1 eq.) using a syringe, and fix the sample vial on a metal module. Transfer it to a 30 mL high -pressure reactor under an argon stream. Replace the atmosphere in the reactor with 40 bar of carbon monoxide, add the internal standard mesitylene (0.5 mmol, 0.5 eq.) and react at 120 °C for 24 h. Use column chromatography to obtain the isolated yield and selectivity of the main product from the reaction mixture. The results are shown in Table 7 below.

[0080] Table 7

[0081]

[0082]

[0083] Comparative Example 1

[0084] Charge Pd(cod)Cl 2 (0.02 mmol, 0.02 eq.), tris(ortho-tolyl)phosphine (0.03 mmol, 0.03 eq.), 5-chlorosalicylic acid (0.2 mmol, 0.2 eq.), boric acid (0.1 mmol, 0.1 eq.), methanol (2.2 mmol, 2.2 eq.), toluene (1 mL) and a magnetic stir bar into a 4 mL sample vial. Seal the container with a special aluminum cap and septum. Inject a 20% by mass 1,3-butadiene toluene solution (1 mmol, 1 eq.) using a syringe, and fix the sample vial on a metal module, then transfer it to a 30 mL high-pressure reactor under an argon stream. Replace the atmosphere in the reactor with carbon monoxide at 40 bar, add the internal standard mesitylene (0.5 mmol, 0.5 eq.), and react at 120 °C for 24 h. Analyze using GC, and the yield of dimethyl adipate is 0% and the selectivity is 0%.

[0085] Comparative Example 2

[0086] Charge Pd(cod)Cl 2 (0.02 mmol, 0.02 eq.), 1,2-bis(4-phosphonato ketone)xylene (0.03 mmol, 0.03 eq.), 5-chlorosalicylic acid (0.2 mmol, 0.2 eq.), boric acid (0.1 mmol, 0.1 eq.), methanol (2.2 mmol, 2.2 eq.), toluene (1 mL) and a magnetic stir bar into a 4 mL sample vial. Seal the container with a special aluminum cap and septum. Inject a 20% by mass 1,3-butadiene toluene solution (1 mmol, 1 eq.) using a syringe, and fix the sample vial on a metal module, then transfer it to a 30 mL high-pressure reactor under an argon stream. Replace the atmosphere in the reactor with carbon monoxide at 40 bar, add the internal standard mesitylene (0.5 mmol, 0.5 eq.), and react at 120 °C for 24 h. Analyze using GC, and the yield of dimethyl adipate is 74% and the selectivity is 95%.

[0087] Comparative Example 3

[0088] Charge a 4 mL sample vial with tris(o-tolyl)phosphine (0.02 mmol, 0.02 eq.), 1,2-bis(4-phosphonato ketone)xylene (0.01 mmol, 0.01 eq.), 5-chlorosalicylic acid (0.2 mmol, 0.2 eq.), boric acid (0.1 mmol, 0.1 eq.), methanol (2.2 mmol, 2.2 eq.), toluene (1 mL) and a magnetic stir bar. Seal the container with a special aluminum cap and septum. Inject a 20% by mass 1,3-butadiene toluene solution (1 mmol, 1 eq.) using a syringe, and fix the sample vial on a metal module. Transfer it to a 30 mL high-pressure reactor under an argon stream. Replace the atmosphere in the reactor with carbon monoxide at 40 bar, add the internal standard mesitylene (0.5 mmol, 0.5 eq.), and react at 120 °C for 24 h. Analyze using GC, and the yield of dimethyl adipate is 0% and the selectivity is 0%.

[0089] Comparative Example 4

[0090] Charge a 4 mL sample vial with Pd(cod)Cl 2 (0.02 mmol, 0.02 eq.), tris(o-tolyl)phosphine (0.02 mmol, 0.02 eq.), 1,2-bis(4-phosphonato ketone)xylene (0.01 mmol, 0.01 eq.), 5-chlorosalicylic acid (0.2 mmol, 0.2 eq.), boric acid (0.1 mmol, 0.1 eq.), methanol (25 mmol, 1 mL) and a magnetic stir bar. Seal the container with a special aluminum cap and septum. Inject a 20% by mass 1,3-butadiene toluene solution (1 mmol, 1 eq.) using a syringe, and fix the sample vial on a metal module. Transfer it to a 30 mL high-pressure reactor under an argon stream. Replace the atmosphere in the reactor with carbon monoxide at 40 bar, add the internal standard mesitylene (0.5 mmol, 0.5 eq.), and react at 120 °C

[0091] for 24 h. Analyze using GC, and the yield of dimethyl adipate is 0% and the selectivity is 0%.

[0092] The applicant declares that the present invention illustrates the method of the present invention through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for the carbonylation of 1,3-conjugated dienes catalyzed by palladium-bidentate ligand tandem to prepare dicarboxylic acid esters, characterized in that, the method comprises the following steps: Adding 1,3-conjugated diene to a reaction solution containing a palladium cation source, a first ligand monodentate phosphine ligand L1, a second ligand bidentate phosphine ligand L2, an anion source, and an alcohol, and then adding a carbon source, reacting to obtain the dicarboxylic acid ester.

2. The method according to claim 1, characterized in that, the palladium cation source includes any one or a combination of at least two of palladium dichloride, palladium dibromide, palladium diiodide, palladium acetate, bis(acetonitrile)palladium dichloride, (1,5-cyclooctadiene)-palladium dichloride, palladium acetylacetonate, palladium trifluoroacetate, palladium pivalate, tris(dibenzylideneacetone)dipalladium or bis(dibenzylideneacetone)palladium.

3. The method according to claim 1 or 2, characterized in that, the first ligand monodentate phosphine ligand L1 is a compound having the structure of formula (I): Among them, R 1 , R 2 and R 3 are independently selected from substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C1-C6 alkoxy, substituted or unsubstituted C3-C8 cycloalkyl, substituted or unsubstituted C6-C18 aryl, substituted or unsubstituted C5-C18 heteroaryl, substituted or unsubstituted C6-C18 aryloxy.

4. The method according to claim 3, characterized in that, the substituents in the substituted group are selected from halogen, C1-C6 alkyl, C1-C6 haloalkyl or C1-C6 alkoxy; Preferably, the substituents in the substituted group are selected from F, methyl, methoxy, ethoxy or trifluoromethyl. Preferably, the R 1 , R 2 and R 3 are independently selected from methyl, n-butyl, tert-butyl, cyclohexyl, methoxy, ethoxy, phenyl, benzyl, phenoxy, benzyloxy, n-butoxy, isopropoxy, methylphenyl, methoxyphenyl, fluorophenyl or trifluoromethylphenyl.

5. The method according to any one of claims 1-4, characterized in that, the first ligand monodentate phosphine ligand L1 is any one of the following compounds:

6. The method according to any one of claims 1-5, characterized in that, the second ligand bidentate phosphine ligand L2 is a compound having the structure of formula (II): wherein R is selected from n is an integer from 1 to 6; R' is selected from phenyl, cyclohexyl or tert-butyl, or two R's and the P to which they are attached form the following ring structure: Preferably, the second ligand bidentate phosphine ligand L2 is selected from any one of the following compounds: wherein R 4 and R 5 are selected from phenyl, cyclohexyl or tert-butyl, n is an integer from 1 to 6; Ph represents phenyl and tBu represents tert-butyl.

7. The method according to any one of claims 1-6, characterized in that, the anion source is selected from any one or a combination of at least two of boric acid, phenylboronic acid, p-tert-butylphenylboronic acid, p-methoxyphenylboronic acid, p-methylphenylboronic acid, p-fluorophenylboronic acid, p-trifluoromethylphenylboronic acid, 5-chlorosalicylic acid / boric acid, 4-vinylphenylboronic acid, bis(pinacolato)diboron or allylboronic acid pinacol ester.

8. The method according to any one of claims 1-7, characterized in that, the alcohol is selected from C1-C20 alcohols; Preferably, the alcohol is selected from any one or a combination of at least two of methanol, ethanol, 1-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, benzyl alcohol or phenethyl alcohol; Preferably, the reaction solvent in the reaction solution is selected from any one or a combination of at least two of alkane solvents, aromatic solvents, ether solvents or amide solvents; Preferably, the reaction solvent is selected from any one or a combination of at least two of n-heptane, toluene, xylene, anisole, diphenyl ether, dichloromethane, 1,2-dichloroethane, N,N-dimethylformamide or N-methylpyrrolidone.

9. The method according to any one of claims 1-8, characterized in that, the 1,3-conjugated diene contains 4 to 30 carbon atoms and has the structure shown in the following formula (III): In formula (III), R 3 , R 4 , R 5 and R 6 are independently selected from hydrogen, C1-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl or C6-C20 aryl; Preferably, the 1,3-conjugated diene is selected from any one or a combination of at least two of 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2,4-dimethyl-1,3-pentadiene, 7-methyl-3-methylene-1,6-octadiene, or 2-phenyl-1,3-butadiene.

10. The method according to any one of claims 1-9, characterized in that, the carbonyl source is selected from carbon monoxide; Preferably, the molar ratio of the palladium cation source, the monodentate phosphine ligand, and the bidentate phosphine ligand is 1:1-2:0.25-0.75; Preferably, the molar ratio of the 1,3-conjugated diene to the palladium cation source is 1:0.005-0.02; Preferably, the molar ratio of the 1,3-conjugated diene to the anion source is 1:0.05-0.20; Preferably, the molar ratio of the 1,3-conjugated diene to the alcohol is 1:2-4; Preferably, the molar ratio of the 1,3-conjugated diene to the reaction solvent in the reaction solution is 1:9-19; Preferably, after adding the carbonyl source, the pressure in the reaction system is 10-60 bar; Preferably, the temperature of the reaction is 100-140 °C; Preferably, the reaction time is 1-24 h.

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