Method for synthesizing adipate through hydrogen esterification of butadiene

Abstract

The invention relates to a method for synthesizing adipate through hydroesterification of butadiene. The method comprises the following steps: a) dissolving a palladium catalyst, a phosphine ligand, acid and butadiene in alcohol and an optional solvent in a reaction kettle; wherein the phosphine ligand is a phosphine ligand as shown in a formula I; b) introducing carbon monoxide into the kettle for reaction; and c) finishing the reaction, and separating to obtain the product. The method has the characteristics of high catalytic efficiency, high product yield, high selectivity, simplicity and convenience in operation and the like.

Description

Technical Field

[0001] This invention relates to the field of chemical production, and specifically, it provides a method for synthesizing adipate by hydrogen esterification of butadiene. Background Technology

[0002] Adipate esters are important C-6 platform compounds and are common polymer monomers for the synthesis of nylon 66, biodegradable polyesters, and polyurethanes. Currently, they are mainly produced via cyclohexane or cyclohexene nitric acid oxidation, a process with long routes, demanding production conditions, and high costs. In particular, it generates a large amount of the greenhouse gas nitrous oxide, necessitating a revolutionary new method for the synthesis of adipate esters. The one-step synthesis of adipate esters via butadiene hydrogen esterification is a simple and efficient route and represents one of the technological trends in adipate ester production. However, existing technologies suffer from a series of problems, such as low selectivity and low conversion rates, which hinder the application of this process.

[0003] The hydrogen esterification of butadiene was first discovered by Brewis and Hughes et al. (Chem. Commun. 1965, 8, 157). Catalyzed by bis(butylphosphine) palladium iodide, butadiene reacts with carbon monoxide and methanol to produce methyl 3-pentenoate, with a yield reaching up to 68%. However, this reaction is subject to harsh conditions (>150℃, 100-1000 atm), resulting in low conversion and selectivity, and only producing a single hydrogen esterified product. BASF has achieved a two-step synthesis of adipate esters using a two-step hydrogen esterification process for butadiene. A novel method (US3161672, US3876695, US4259501) using a cobalt-based metal catalyst was proposed, but the reaction conditions were also harsh (>150℃, 100-300 atm), and the selectivity was only 60-80%. Subsequently, companies such as DuPont (US4777284) and Shell (US4861912, WO00056695) investigated the hydrogen esterification of butadiene to prepare adipate, but neither the conversion rate nor the selectivity was improved. Later, US4575562 disclosed a method using trialkyl or triarylphosphine as ligands and palladium-catalyzed hydrogen esterification of butadiene to synthesize adipate, but the conversion rate was only 50% and the selectivity only 70%.

[0004] In 2019, Beller et al. achieved a breakthrough in the direct hydrogen esterification of butadiene using their newly developed bisphosphine ligand, HeMaRaphos, generating dimethyl adipate with 95% conversion and 97% selectivity at 120 °C and 40 atm (Science 2019, 366, 1514–1517). In 2021, building on their previous work, the same group achieved palladium-catalyzed hydrogen esterification of butadiene to synthesize diadipate using the simpler bidentate phosphine ligand dtbpx (Angew. Chem. Int. Ed. 2021, 60, 9527). However, the highest turnover number (TON) of the above reactions was only 60,000, and the conversion frequency (TOF) was only about 1000 / hour, indicating that the catalytic efficiency still needs improvement. CN116925140 discloses the preparation of a heterogeneous catalyst based on bidentate phosphine ligand dtbpx and its application in the hydrogen esterification of butadiene to prepare adipate, but the conversion number of the reaction is 50,000, which has not been improved.

[0005] In summary, the existing palladium-catalyzed butadiene hydrogen esterification reaction has mild conditions, but its low catalytic activity results in low conversion number and conversion frequency, which affects the industrial application of this process. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing adipate esters (including methyl ester, ethyl ester, butyl ester, or octyl ester, etc.), the method comprising the steps of:

[0007] a) In a reaction vessel, the palladium catalyst, phosphine ligand, acid and butadiene are dissolved in alcohol and optional solvent;

[0008] b) Introduce carbon monoxide into the reactor to carry out the reaction;

[0009] c) End the reaction and separate the product;

[0010] Wherein, the phosphine ligand is the phosphine ligand shown in Formula I;

[0011]

[0012] in,

[0013] R 1 Selected from the following group: substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 3-12 cycloalkyl, substituted or unsubstituted C 6-30 Aryl;

[0014] R 2 Selected from the following group: substituted or unsubstituted 5-20 member heteroaryl groups;

[0015] R 3C is hydrogen, substituted or unsubstituted 1-10 Alkyl, substituted or unsubstituted C 1-10 Alkoxy, substituted or unsubstituted C 2-10 Ester group, cyano group, COOH group, benzenesulfonyl group, trialkylsilyl group (wherein the alkyl group is C10). 1-4 Alkyl), nitro, substituted or unsubstituted C 6-30 Aryl, substituted or unsubstituted 5-30 membered heteroaryl; or two R atoms located on adjacent carbon atoms 3 The carbon atoms bonded to it together form a group selected from the following group: C 6-10 Aryl, 5-12 heteroaryl;

[0016] In the ligands described, A is either substituted or unsubstituted C. 1-4 Alkylene Or the aforementioned A and Together in, This is the connection point connected to P;

[0017] Among them, R 4 These are one or more substituents selected from the following group located on the corresponding ring: H, C 1-10 Alkyl, C 1-10 Alkoxy, C 2-10 Ester group, cyano group, COOH group, benzenesulfonyl group, trialkylsilyl group (wherein the alkyl group is C 1-4 alkyl), nitro, C 6-30 Aryl, 5-30 quinone heteroaryl; or with R 3 One or more ring atoms on the pyridine ring together form a 5-7 membered carbon ring or heterocycle;

[0018] Unless otherwise specified, the substitution refers to the substitution of one or more hydrogen atoms on the group by a substituent selected from the group consisting of: C 1-10 Alkyl, C 1-10 Alkoxy, C 2-10 Ester group, cyano group, COOH group, benzenesulfonyl group, trialkylsilyl group (wherein the alkyl group is C10). 1-4 alkyl), nitro, C 6-30 Aryl, 5-30 heteroaryl.

[0019] In another preferred embodiment, A in the ligand is CH2 or Or the aforementioned A and Together in, This is the connection point connected to P;

[0020] Among them, R 4 These are one or more substituents selected from the following group located on the corresponding ring: H, C1-10 Alkyl, C 1-10 Alkoxy, C 2-10 Ester group, cyano group, COOH group, benzenesulfonyl group, trialkylsilyl group (wherein the alkyl group is C 1-4 alkyl).

[0021] In another preferred embodiment, the ligand,

[0022] R 1 Selected from the following group: substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 3-10 cycloalkyl groups;

[0023] R 2 Selected from the following group: substituted or unsubstituted 5-10 member heteroaryl groups;

[0024] R 3 For hydrogen, C 1-10 Alkyl, C 1-10 Alkoxy, C 2-10 Ester group, cyano group, trialkylsilyl group (wherein the alkyl group is C10) 1-4 Alkyl), nitro, -CH(Ph)2, C 6-30 Aryl, 5-10 heteroaryl.

[0025] In another preferred embodiment, the ligand,

[0026] R 1 Selected from the group consisting of: methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, isobutyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, or phenyl;

[0027] R 2 Selected from the group consisting of: pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrroleyl, imidazolyl, pyrazolyl, thiophenyl, furanyl, thiazolyl, triazolyl, quinolinyl, isoquinolinyl; and the R... 2 It may optionally be substituted by one or more substituents selected from the following group: C 1-4 alkyl;

[0028] R 3 Selected from the following group: methyl, n-propyl, isopropyl, tert-butyl, methoxy, cyano, COOH, -CH(Ph)2, benzenesulfonyl, trimethylsilyl, isoquinolinyl.

[0029] In another preferred embodiment, the ligand is selected from the group consisting of:

[0030]

[0031]

[0032] In another preferred embodiment, the reactor is a high-pressure reactor.

[0033] In another preferred embodiment, the amount of the phosphine ligand is 0.00001 to 10% molar equivalent of the butadiene, more preferably 0.001 to 1% molar equivalent.

[0034] In another preferred embodiment, the reaction temperature is 0–200°C, preferably 60–130°C.

[0035] In another preferred embodiment, the reaction is carried out under the protection of an inert gas; preferably, the inert gas is nitrogen and / or argon.

[0036] In another preferred embodiment, the reaction is carried out at 1-10 MPa; more preferably, the reaction is carried out at 2-8 MPa.

[0037] In another preferred embodiment, the reaction time is 0.5 to 72 hours, preferably 0.5 to 24 hours.

[0038] In another preferred embodiment, the alcohol is C10. 1-12 Alkyl alcohols; preferably, the alcohols are selected from the group consisting of methanol, ethanol, propanol, butanol, octanol, or combinations thereof.

[0039] In another preferred embodiment, the amount of alcohol used in the reaction is 1-100 molar equivalents of the butadiene, preferably 1-10 molar equivalents.

[0040] In another preferred embodiment, the palladium catalyst is selected from the group consisting of palladium acetate, palladium trifluoroacetate, palladium pentavalerate, palladium tetrafluoroborate tetraacetonitrile, palladium hexafluoroacetylacetonate, bis(acetylacetonate)palladium, palladium tetraacetonitrile trifluoromethanesulfonate, palladium neopentanoate, bis(dibenzylacetonate)palladium, tri(dibenzylacetonate)palladium, palladium chloride, (1,5-cyclooctadiene)palladium dichloride, palladium diacetonitrile dichloride, palladium dibenzonitrile dichloride, or combinations thereof.

[0041] In another preferred embodiment, the palladium catalyst is selected from the group consisting of palladium acetate, palladium trifluoroacetate, palladium pentavalerate, tris(dibenzylacetone)palladium, palladium chloride, (1,5-cyclooctadiene)palladium dichloride, palladium diacetonitrile, or combinations thereof.

[0042] In another preferred embodiment, the amount of palladium catalyst used is 0.00001 to 10% molar equivalent of butadiene, more preferably 0.0001 to 1% molar equivalent.

[0043] In the reaction described, when the phosphine ligand is a nitrogen-phosphine ligand (i.e., compound of formula I), the molar ratio of the palladium catalyst to the nitrogen-phosphine ligand is 1:1 to 1:30, more preferably 1:1 to 1:10.

[0044] In another preferred embodiment, the acid is selected from the group consisting of: perchloric acid, sulfuric acid, phosphoric acid, sulfonic acid, alkylphosphonic acid, alkylsulfonic acid, alkylcarboxylic acid, perfluoroalkylsulfonic acid, perfluoroalkylcarboxylic acid, or arylsulfonic acid.

[0045] In another preferred embodiment, the alkyl group is C10. 1-12 alkyl.

[0046] In another preferred embodiment, the aryl group is C 6-10 Aryl.

[0047] In another preferred embodiment, the acid is selected from the group consisting of: methanesulfonic acid, trifluoromethanesulfonic acid, tert-butanesulfonic acid, p-toluenesulfonic acid (PTSA), 2-hydroxypropane-2-sulfonic acid, 2,4,6-trimethylbenzenesulfonic acid, dodecyl sulfonic acid, sulfuric acid, sulfonic acid, formic acid, and trifluoroacetic acid.

[0048] In another preferred embodiment, the amount of acid used is 0.00004 to 40% molar equivalent of the butadiene, preferably 0.0004 to 4% molar equivalent.

[0049] In another preferred embodiment, the solvent is selected from the group consisting of alkane solvents, substituted aromatic solvents, ether solvents, ketone solvents, nitrile solvents, ester solvents, or combinations thereof.

[0050] In another preferred embodiment, the alkane solvent is selected from the group consisting of n-hexane, cyclohexane, or combinations thereof.

[0051] In another preferred embodiment, the substituted aromatic solvent is selected from the group consisting of chlorobenzene, toluene, xylene, and trifluorotoluene.

[0052] In another preferred embodiment, the ether solvent is selected from the group consisting of tetrahydrofuran, diethyl ether, methyl tert-butyl ether, ethyl tert-butyl ether, anisole, ethylene glycol dimethyl ether, 1,4-dioxane, or combinations thereof.

[0053] In another preferred embodiment, the ketone solvent is selected from the group consisting of acetone.

[0054] In another preferred embodiment, the nitrile solvent is selected from the group consisting of acetonitrile, propionitrile, benzonitrile, or combinations thereof.

[0055] In another preferred embodiment, the ester solvent is selected from the group consisting of ethyl acetate.

[0056] In another preferred embodiment, the alcohol is methanol, and the reaction is carried out under the following conditions:

[0057] a) Dissolve palladium trifluoroacetate, phosphine ligand, acid and butadiene in methanol or a mixture of solvents with optional solvents;

[0058] b) Carbon monoxide is introduced into the reactor to carry out the reaction, wherein the reaction is carried out at room temperature to 130°C;

[0059] c) End the reaction and separate the product.

[0060] In another preferred embodiment, the alcohol is ethanol, and the reaction is carried out under the following conditions:

[0061] a) Dissolve palladium trifluoroacetate, phosphine ligand, acid and butadiene in ethanol or a mixture of solvents with optional solvents;

[0062] b) Carbon monoxide is introduced into the reactor to carry out the reaction, wherein the reaction is carried out at room temperature to 130°C;

[0063] c) End the reaction and separate the product.

[0064] In another preferred embodiment, the alcohol is butanol, and the reaction is carried out under the following conditions:

[0065] a) Dissolve palladium trifluoroacetate, phosphine ligand, acid, and butadiene in butanol or a mixture thereof with an optional solvent.

[0066] b) Carbon monoxide is introduced into the reactor to carry out the reaction, wherein the reaction is carried out at room temperature to 130°C;

[0067] c) End the reaction and separate the product.

[0068] In another preferred embodiment, the alcohol is octanol, and the reaction is carried out under the following conditions:

[0069] a) Dissolve palladium trifluoroacetate, phosphine ligand, acid, and butadiene in octanol or a mixture thereof with an optional solvent.

[0070] b) Carbon monoxide is introduced into the reactor to carry out the reaction, wherein the reaction is carried out at room temperature to 130°C;

[0071] c) End the reaction and separate the product.

[0072] It should be understood that, within the scope of this invention, the above-described technical features of this invention and the technical features specifically described below (such as in the embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be described in detail here. Detailed Implementation

[0073] Based on long-term and in-depth research, the inventors have prepared a series of novel phosphine ligands and a method for synthesizing adipate esters by butadiene hydrogen esterification based on these ligands. This method can improve the catalytic efficiency of butadiene hydrogen esterification reaction, increase butadiene conversion and product selectivity, and the reaction conditions are mild and the operation is simple. Based on the above findings, the inventors have completed this invention.

[0074] definition

[0075] In this invention, "room temperature" refers to 10–30°C.

[0076] In this invention, the term "alkyl" refers to a straight-chain or branched saturated hydrocarbon group, preferably C10. 1-10 Alkyl groups (e.g., C15) 1-8 alkyl, C 1-6 alkyl, C 1-4 Alkyl groups).

[0077] In this invention, the term "cycloalkyl" refers to a saturated monocyclic ring, or a carbocyclic substituent comprising a fused, bridged, or spirocyclic polycyclic system, preferably C14. 3-8 cycloalkyl (e.g., C10) 3-6 (cycloalkyl groups).

[0078] In this invention, the term "alkoxy" refers to a cyclic or acyclic alkyl group connected by an oxygen bridge. The definitions of alkyl and cycloalkyl are as described above, and C is preferred. 1-10 alkoxy groups (e.g., C) 1-8 alkoxy, C 1-6 alkoxy, C 1-4 (alkoxy group).

[0079] Unless otherwise specified, in this invention, "aryl" refers to a group having 6-30 (preferably 6-14) ring carbon atoms and zero heteroatoms, a monocyclic or polycyclic (e.g., bicyclic or tricyclic) 4n+2 aromatic ring system (e.g., having 6, 10, or 14 shared p electrons in a cyclic array), preferably C6-C. 14 Aryl, more preferably C6-C 10 Aryl).

[0080] Unless otherwise specified, in this invention, "heteroaryl" refers to a monocyclic or polycyclic (e.g., bicyclic or tricyclic) 4n+2 aromatic ring system (e.g., having 6, 10, or 14 shared p electrons in a cyclic array) having 5-30 (preferably 5-20, more preferably 5-14) ring atoms (the ring atoms may be carbon atoms or heteroatoms), preferably 5-15-membered heteroaryl, more preferably 5-9-membered heteroaryl, wherein the heteroatoms are selected from the group consisting of O, N, and S.

[0081] Without violating common sense in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0082] The reagents and raw materials used in this invention are all commercially available.

[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. Percentages and parts are by weight unless otherwise stated.

[0084] Example 1

[0085] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), bisphosphine ligand L1 (6.2 mg, 0.02 mmol), methanesulfonic acid (6.5 μL, 0.10 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure inside the autoclave was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis revealed a yield of 81% for dimethyl adipate, with a selectivity greater than 90% for the target product.

[0086] Example 2

[0087] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), bisphosphine ligand L2 (7.1 mg, 0.02 mmol), methanesulfonic acid (6.5 μL, 0.10 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure inside the autoclave was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed a yield of 77% for dimethyl adipate and a selectivity greater than 90% for the target product.

[0088] Example 3

[0089] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), bisphosphine ligand L3 (5.9 mg, 0.02 mmol), methanesulfonic acid (6.5 μL, 0.10 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was then displaced, and the pressure inside the autoclave was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis revealed a methyl adipate yield of 75% and a selectivity for the target product greater than 90%.

[0090] Example 4

[0091] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), bisphosphine ligand L4 (14.5 mg, 0.04 mmol), p-toluenesulfonic acid (17.2 mg, 0.10 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis revealed a dimethyl adipate yield of 81%, with a target product selectivity greater than 90% (relative to the selectivity of the monohydroesterification product, the same below).

[0092] Example 5

[0093] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), bisphosphine ligand L5 (14.4 mg, 0.04 mmol), methanesulfonic acid (6.5 μL, 0.10 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed a yield of 85% for dimethyl adipate and a selectivity greater than 90% for the target product.

[0094] Example 6

[0095] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), bisphosphine ligand L6 (14.6 mg, 0.04 mmol), p-toluenesulfonic acid (17.2 mg, 0.10 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure inside the autoclave was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis revealed a methyl adipate yield of 77% and a target product selectivity of 85%.

[0096] Example 7

[0097] To a 300 mL Parr autoclave under nitrogen protection, palladium trifluoroacetate (3.3 mg, 0.01 mmol), bisphosphine ligand L7 (14.5 mg, 0.04 mmol), trifluoromethanesulfonic acid (14.2 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), butanol (5 mL), tetrahydrofuran (10 mL), and a stir bar were added to displace carbon monoxide gas. The pressure inside the autoclave was then increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis revealed a yield of 78% for dibutyl adipate and a selectivity of 88% for the target product.

[0098] Example 8

[0099] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), bisphosphine ligand L8 (20.0 mg, 0.04 mmol), dodecyl sulfonic acid (26.1 mg, 0.08 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure inside the autoclave was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed a yield of 79% for dimethyl adipate and a selectivity of 89% for the target product.

[0100] Example 9

[0101] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), bisphosphine ligand L9 (8.2 mg, 0.02 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), octanol (10 mL), n-hexane (10 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis revealed a yield of 83% for dioctyl adipate and a selectivity of 85% for the target product.

[0102] Example 10

[0103] Palladium acetate (2.2 mg, 0.01 mmol), bisphosphine ligand L10 (7.3 mg, 0.02 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure inside the autoclave was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 6 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed that the yield of dimethyl adipate was 81%, with a selectivity for the target product greater than 90%.

[0104] Example 11

[0105] Palladium trifluoroacetate (0.3 mg, 0.001 mmol), bisphosphine ligand L12 (2.3 mg, 0.004 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure inside the autoclave was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed that the yield of dimethyl adipate was 81%, with a selectivity for the target product greater than 90%.

[0106] Example 12

[0107] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), bisphosphine ligand L13 (7.8 mg, 0.02 mmol), trifluoromethanesulfonic acid (14.2 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure inside the autoclave was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed that the yield of dimethyl adipate was 80%, with a selectivity for the target product greater than 90%.

[0108] Example 13

[0109] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), bisphosphine ligand L14 (16.8 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure inside the autoclave was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed that the yield of dimethyl adipate was 83%, with a selectivity for the target product greater than 90%.

[0110] Example 14

[0111] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), bisphosphine ligand L15 (17.4 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed a yield of 82% for dimethyl adipate and a selectivity greater than 90% for the target product.

[0112] Example 15

[0113] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), phosphine ligand L16 (12.0 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed a yield of 75% for dimethyl adipate and a selectivity greater than 90% for the target product.

[0114] Example 16

[0115] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), phosphine ligand L17 (15.2 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed a yield of 73% for dimethyl adipate and a selectivity greater than 90% for the target product.

[0116] Example 17

[0117] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), phosphine ligand L18 (12.9 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis revealed a yield of 75% for dimethyl adipate and a selectivity of 89% for the target product.

[0118] Example 18

[0119] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), phosphine ligand L19 (15.2 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure inside the autoclave was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed a yield of 70% for dimethyl adipate and a selectivity of 85% for the target product.

[0120] Example 19

[0121] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), phosphine ligand L20 (17.2 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed a yield of 76% for dimethyl adipate and a selectivity greater than 90% for the target product.

[0122] Example 20

[0123] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), phosphine ligand L21 (15.6 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure inside the autoclave was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed a yield of 91% for dimethyl adipate and a selectivity greater than 90% for the target product.

[0124] Example 21

[0125] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), phosphine ligand L22 (18.4 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed a yield of 90% for dimethyl adipate and a selectivity greater than 90% for the target product.

[0126] Example 22

[0127] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), phosphine ligand L23 (18.4 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed a yield of 88% for dimethyl adipate and a selectivity greater than 90% for the target product.

[0128] Example 23

[0129] Palladium trifluoroacetate (3.3 mg, 0.01 mmol), phosphine ligand L24 (16.3 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed a yield of 85% for dimethyl adipate and a selectivity greater than 90% for the target product.

[0130] Example 24

[0131] In a 300 mL Parr autoclave under nitrogen protection, Pd(CH3CN)4(BF4)2 (4.4 mg, 0.01 mmol), phosphine ligand L22 (18.4 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), methanol (10 mL), 1,4-dioxane (10 mL), and a stir bar were added to displace carbon monoxide gas. The pressure inside the autoclave was then increased to 4 MPa. The mixture was rapidly heated to 100 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed that the yield of dimethyl adipate was 80%, with a selectivity of 88% for the target product.

[0132] Example 25

[0133] In a 300 mL Parr autoclave under nitrogen protection, Pd(hfacac)₂ (3.1 mg, 0.01 mmol), phosphine ligand L₂₂ (18.4 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), butanol (5 mL), tetrahydrofuran (15 mL), and a stir bar were added to displace carbon monoxide. The pressure inside the autoclave was then increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed that the yield of dibutyl adipate was 75%, with a selectivity of 87% for the target product.

[0134] Example 26

[0135] Palladium acetate (2.2 mg, 0.01 mmol), phosphine ligand L22 (18.4 mg, 0.04 mmol), p-toluenesulfonic acid (17.2 mg, 0.10 mmol), butadiene (5.4 g, 100 mmol), octanol (5 mL), tetrahydrofuran (15 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure inside the autoclave was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed that the yield of dioctyl adipate was 86%, with a selectivity for the target product greater than 90%.

[0136] Example 27

[0137] Pd₂(dba)₃ (4.6 mg, 0.005 mmol), phosphine ligand L₂₂ (18.4 mg, 0.04 mmol), trifluoroacetic acid (12 μL, 0.16 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed a yield of 85% for dimethyl adipate and a selectivity greater than 90% for the target product.

[0138] Example 28

[0139] Palladium trifluoroacetate (0.3 mg, 0.001 mmol), phosphine ligand L22 (18.4 mg, 0.04 mmol), methanesulfonic acid (1.0 μL, 0.016 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure inside the autoclave was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 24 hours. After the reaction, NMR analysis showed a yield of 88% for dimethyl adipate and a selectivity greater than 90% for the target product.

[0140] Example 29

[0141] Palladium trifluoroacetate (0.03 mg, 0.0001 mmol), phosphine ligand L22 (18.4 mg, 0.04 mmol), methanesulfonic acid (0.3 μL, 0.004 mmol), butadiene (5.4 g, 100 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Carbon monoxide gas was displaced, and the pressure inside the autoclave was increased to 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 48 hours. After the reaction, NMR analysis showed a yield of 80% for dimethyl adipate and a selectivity greater than 90% for the target product.

[0142] The phosphine ligands of the present invention can produce adipate products in high yields (>75%, >95% in the best example) with good selectivity when used for catalytic preparation of adipate esters, and therefore have potential industrial applications.

[0143] Furthermore, the phosphine ligands of the present invention exhibit good catalytic conversion rates, thus enabling catalytic conversion at low dosages (<10). -4 Equivalent, preferably <10 -5 Equivalent, preferably <10 -6 The catalytic reaction is completed in equivalent quantities.

[0144] All documents mentioned in this invention are incorporated herein by reference as if each document were individually incorporated by reference. Furthermore, it should be understood that after reading the foregoing teachings of this invention, those skilled in the art can make various alterations or modifications to this invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for synthesizing adipate by palladium-catalyzed hydrogen esterification of butadiene, characterized in that, The method includes the following steps: a) In a reaction vessel, the palladium catalyst, phosphine ligand, acid and butadiene are dissolved in alcohol and optional solvent; b) Introduce carbon monoxide into the reactor to carry out the reaction; c) End the reaction and separate the product; Wherein, the phosphine ligand is the phosphine ligand shown in Formula I; in, R 1 Selected from the following group: substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 3-12 cycloalkyl, substituted or unsubstituted C 6-30 Aryl; R 2 Selected from the following group: substituted or unsubstituted 5-20 member heteroaryl groups; R 3 C is hydrogen, substituted or unsubstituted 1-10 Alkyl, substituted or unsubstituted C 1-10 Alkoxy, substituted or unsubstituted C 2-10 Ester group, cyano group, COOH group, benzenesulfonyl group, trialkylsilyl group (wherein the alkyl group is C10). 1-4 Alkyl), nitro, substituted or unsubstituted C 6-30 Aryl, substituted or unsubstituted 5-30 membered heteroaryl; or two R atoms located on adjacent carbon atoms 3 The carbon atoms bonded to it together form a group selected from the following group: C 6-10 Aryl, 5-12 heteroaryl; In the ligands described, A is either substituted or unsubstituted C. 1-4 Alkylene Or the aforementioned A and Together in, This is the connection point connected to P; Among them, R 4 These are one or more substituents selected from the following group located on the corresponding ring: H, C 1-10 Alkyl, C 1-10 Alkoxy, C 2-10 Ester group, cyano group, COOH group, benzenesulfonyl group, trialkylsilyl group (wherein the alkyl group is C 1-4 alkyl), nitro, C 6-30 Aryl, 5-30 quinone heteroaryl; or with R 3 One or more ring atoms on the pyridine ring together form a 5-7 membered carbon ring or heterocycle; Unless otherwise specified, the substitution refers to the substitution of one or more hydrogen atoms on the group by a substituent selected from the group consisting of: C 1-10 Alkyl, C 1-10 Alkoxy, C 2-10 Ester group, cyano group, COOH group, benzenesulfonyl group, trialkylsilyl group (wherein the alkyl group is C10). 1-4 alkyl), nitro, C 6-30 Aryl, 5-30 heteroaryl.

2. The method as described in claim 1, characterized in that, In the ligand, A is CH2 or Or the aforementioned A and Together in, This is the connection point connected to P; Among them, R 4 These are one or more substituents selected from the following group located on the corresponding ring: H, C 1-10 Alkyl, C 1-10 Alkoxy, C 2-10 Ester group, cyano group, COOH group, benzenesulfonyl group, trialkylsilyl group (wherein the alkyl group is C 1-4 alkyl).

3. The method as described in claim 1, characterized in that, In the ligands described, R 1 Selected from the following group: substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 3-10 cycloalkyl groups; R 2 Selected from the following group: substituted or unsubstituted 5-10 member heteroaryl groups; R 3 For hydrogen, C 1-10 Alkyl, C 1-10 Alkoxy, C 2-10 Ester group, cyano group, trialkylsilyl group (wherein the alkyl group is C10) 1-4 Alkyl), nitro, -CH(Ph)2, C 6-30 Aryl, 5-10 heteroaryl.

4. The method as described in claim 1, characterized in that, In the ligands described, R 1 Selected from the group consisting of: methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, isobutyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, or phenyl; R 2 Selected from the group consisting of: pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrroloyl, imidazolyl, pyrazolyl, thiophenyl, furanyl, thiazolyl, and triazolyl; and wherein the R... 2 It may optionally be substituted by one or more substituents selected from the following group: C 1-4 alkyl; R 3 Selected from the following group: methyl, n-propyl, isopropyl, tert-butyl, methoxy, cyano, COOH, -CH(Ph)2, benzenesulfonyl, trimethylsilyl.

5. The method as described in claim 1, characterized in that, The ligands are selected from the following group:

6. The method as described in claim 1, characterized in that, The amount of the phosphine ligand used is 0.00001 to 10% molar equivalent of the butadiene.

7. The method as described in claim 1, characterized in that, When the phosphine ligand is a bisphosphine ligand (i.e., compound of formula I), the molar ratio of the palladium catalyst to the bisphosphine ligand is 1:0.5 to 1:

30.

8. The method as described in claim 1, characterized in that, The alcohol is C 1-12 Alkyl alcohols; preferably, the alcohols are selected from the group consisting of methanol, ethanol, propanol, butanol, octanol, or combinations thereof.

9. The method as described in claim 1, characterized in that, The palladium catalyst is selected from the group consisting of palladium acetate, palladium trifluoroacetate, palladium pentavalerate, palladium tetrafluoroborate tetraacetonitrile, palladium hexafluoroacetylacetonate, bis(acetylacetonate)palladium, palladium tetraacetonitrile trifluoromethanesulfonate, palladium neopentanoate, bis(dibenzylacetonate)palladium, tri(dibenzylacetonate)palladium, palladium chloride, (1,5-cyclooctadiene)palladium dichloride, palladium diacetonitrile dichloride, palladium dibenzonitrile dichloride, or combinations thereof.

10. The method as described in claim 1, characterized in that, The acid is selected from the group consisting of: perchloric acid, sulfuric acid, phosphoric acid, sulfonic acid, alkyl phosphoric acid, alkyl sulfonic acid, alkyl carboxylic acid, perfluoroalkyl sulfonic acid, perfluoroalkyl carboxylic acid, and aryl sulfonic acid.

11. The method as described in claim 1, characterized in that, The solvent is selected from the group consisting of alkane solvents, substituted aromatic solvents, ether solvents, ketone solvents, nitrile solvents, ester solvents, or combinations thereof.

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