Phosphine ligands and their use in the synthesis of acrylates from ethynyl carbonyl compounds

Abstract

The present application relates to phosphine ligands and their use in the synthesis of acrylates by carbonylation of acetylene. The phosphine ligands of the present application are represented by Formula I. The phosphine ligands of the present application can be used in combination with a palladium catalyst to catalyze the carbonylation of acetylene to synthesize acrylates. The method has the characteristics of high catalytic efficiency, high product yield, high selectivity, simple operation and the like.

Description

Technical Field

[0001] This invention relates to phosphine ligands and their application in the carbonylation synthesis of acrylates from acetylene. Background Technology

[0002] Acrylic esters are important chemical raw materials, mainly used in the synthesis of resin monomers, and are widely used in coatings, adhesives, textiles, rubber, and other industries. Driven by the construction, textile, and packaging sectors, my country's consumption of acrylic acid (esters) has continued to grow rapidly. Propylene oxidation has always been the main method for industrial production of acrylic acid. However, with the increasing depletion of petroleum resources and rising prices, the development of alternative routes using petrochemical products as raw materials has received widespread attention. Therefore, the synthesis of acrylic acid (esters) via acetylene carbonylation, a non-petroleum route, will be more competitive and is one of the technological development trends in acrylic acid (ester) production.

[0003] The synthesis of acrylic acid by acetylene carbonylation was first invented by W. Reppe in Germany (US2653969). In the presence of nickel tetracarbonyl, acetylene-carbon monoxide-water (alcohol) is converted to acrylic acid (ester). This reaction requires high conditions (>150℃, 1-3 MPa), suffers from severe catalyst loss, and is highly toxic. Improvements by Rohmd-Hass and Dow-Badische, BASF, led to its industrial application (US2582911, US2964558, US3060228, US2881205, US2845451, US2886591, US2883418). To date, hundreds of catalysts have been reported for this reaction, but they are primarily based on nickel halides or copper halides. While these halogen-containing catalysts offer good yields and selectivity, they suffer from long reaction times, carbon buildup during the reaction, and severe equipment corrosion.

[0004] Alper et al. discovered that palladium acetate can facilitate the hydrocarbonylation of alkynes to synthesize α,β-unsaturated acids under the promotion of acid and phosphine ligands (Organometallics 1993, 12, 712; J.Org.Chem. 1993, 58, 4739). The authors found that the phosphine ligand is crucial for both reactivity and selectivity. In 2009, patent CN101768070A disclosed the synthesis of acrylic acid from acetylene carbonylation under mild conditions (40℃, 5MPa) using palladium acetate as a catalyst, sulfonic acid as an auxiliary agent, and 2-pyridyldiphenylphosphine as a ligand; however, the acetylene conversion rate of this method was low (<42%). In 2015, Zhou Qilin et al. utilized a Pd(II) / Xantphos catalytic system with formic acid as the carbonyl source to achieve the carbonylation of acetylene to synthesize acrylic acid, achieving a maximum TON of 140 (Angew.Chem.Int.Ed. 2015, 54, 6302). Although the palladium catalytic system has relatively mild conditions and good reaction selectivity, the catalyst activity is currently not high enough, i.e. the catalytic conversion number is low, which affects the industrial application of this process. Summary of the Invention

[0005] The purpose of this invention is to provide a catalyst for the carbonylation of acetylene to prepare acrylates.

[0006] Another object of the present invention is to provide a process for preparing acrylates (e.g., methyl acrylate, ethyl acrylate, butyl acrylate or octyl acrylate).

[0007] In a first aspect, the present invention provides a phosphine ligand having a structure selected from the group I:

[0008]

[0009] in,

[0010] R 1 and R 4 Each is independently selected from the following group: substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 3-10 cycloalkyl, substituted or unsubstituted C 6-30 Aryl;

[0011] R 2 and R 3 Each is independently selected from the group consisting of substituted or unsubstituted 5-20 heteroaryl groups;

[0012] A represents unsubstituted or unreplaced by one or more R's. 6 The substituted 5-10-membered heteroaryl group, wherein the heteroatom in the heteroaryl group is one or more of O, N, and S, and may be the same or different;

[0013] R 5 and R 6 Each is an independent substituent located on the corresponding ring and selected from the following groups: 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 membered heteroaryl; or two R atoms located on adjacent ring atoms 5 The ring atoms attached to it together form 5-7 membered carbon rings or heterocycles;

[0014] 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;

[0015] And the compound is not

[0016] In another preferred embodiment, when A is pyrrole, the compound satisfies any 1-3 of the following conditions (1)-(3):

[0017] (1)R 5 R 6 They are not both hydrogen;

[0018] (2)R 1 R 4 Not both tert-butyl;

[0019] (3)R 2 and R 3 It is not 2-pyridyl.

[0020] In another preferred embodiment, the ligand,

[0021] R 1 and R 4 Each is independently selected from the following group: substituted or unsubstituted C 1-4 Alkyl, substituted or unsubstituted C 3-10 cycloalkyl, phenyl;

[0022] R 2 and R 3 Each is independently selected from the following group: substituted or unsubstituted 5-20 heteroaryl groups;

[0023] Wherein, the R 1 R 2 R 3 and R 4 Each is independently unsubstituted or substituted by 1-2 substituents selected from the group consisting of: methyl, methoxy, cyano, COOH, benzenesulfonyl, and trimethylsilyl.

[0024] In another preferred embodiment, A is unsubstituted or substituted by one or more R. 6 The substituted 5-9-membered heteroaryl group, wherein the heteroatom in the heteroaryl group is one or more of O, N, and S, and may be the same or different.

[0025] In another preferred embodiment, the ligand,

[0026] R 1 and R 4 Each of the following is independently selected: methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, isobutyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl or phenyl;

[0027] R 2 and R 3 Each of the following groups is independently selected: pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrroleyl, imidazolyl, pyrazolyl, thiopheneyl, furanyl, thiazolyl, triazolyl;

[0028] Wherein, the R 1 R 2 R 3 and R 4 Each is independently unsubstituted or substituted by 1-2 substituents selected from the group consisting of: methyl, methoxy, cyano, COOH, benzenesulfonyl, and trimethylsilyl.

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

[0030]

[0031] A second aspect of the present invention provides a method for synthesizing acrylates by palladium-catalyzed acetylene carbonylation, the method comprising the steps of:

[0032] a) In a reaction vessel, a palladium catalyst, a phosphine ligand, and an acid are dissolved in an alcohol and, optionally, a solvent; wherein the phosphine ligand is a ligand of Formula I as described in the first aspect, or

[0033] b) Introduce acetylene into the reactor, followed by carbon monoxide, to carry out the reaction;

[0034] c) End the reaction and separate the product.

[0035] In another preferred embodiment, the reactor is a high-pressure reactor.

[0036] In another preferred embodiment, the amount of the phosphine ligand is 0.00001 to 10% molar equivalent of the acetylene, more preferably 0.0001 to 1% molar equivalent.

[0037] In another preferred embodiment, the reaction temperature is 0–200°C, preferably 40–130°C.

[0038] 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.

[0039] In another preferred embodiment, the reaction is carried out at 1-10 MPa; more preferably, the reaction is carried out at 2-8 MPa.

[0040] In another preferred embodiment, the reaction time is 0.5 to 72 hours, preferably 0.5 to 24 hours.

[0041] In another preferred embodiment, 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.

[0042] In another preferred embodiment, the amount of alcohol used in the reaction is 1-100 molar equivalents of the acetylene, preferably 1-10 molar equivalents.

[0043] 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, palladium diacetonitrile dichloride, palladium dibenzonitrile dichloride, or combinations thereof.

[0044] In another preferred embodiment, the palladium catalyst is selected from the group consisting of palladium acetate, palladium trifluoroacetate, palladium pentavalerate, tris(dibenzylideneacetone)palladium, palladium chloride, or combinations thereof.

[0045] In another preferred embodiment, the amount of palladium catalyst used is 0.00001 to 10% molar equivalent of the acetylene, more preferably 0.001 to 1% molar equivalent.

[0046] In another preferred embodiment, 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 1:1 to 1:30, more preferably 1:1 to 1:5.

[0047] 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, and perfluoroalkylcarboxylic acid (wherein the alkyl group is C). 1-12 alkyl), arylsulfonic acid (wherein the aryl group is C10), 6-10 Aryl).

[0048] 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.

[0049] In another preferred embodiment, the amount of acid used is 0.00004 to 40% molar equivalent of the acetylene, preferably 0.004 to 4% molar equivalent.

[0050] 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.

[0051] In another preferred embodiment, the alkane solvent is selected from the group consisting of n-hexane, cyclohexane, or combinations thereof.

[0052] In another preferred embodiment, the substituted aromatic solvent is selected from the group consisting of chlorobenzene, toluene, xylene, and trifluorotoluene.

[0053] 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.

[0054] In another preferred embodiment, the ketone solvent is selected from the group consisting of acetone.

[0055] In another preferred embodiment, the nitrile solvent is selected from the group consisting of acetonitrile, propionitrile, benzonitrile, or combinations thereof.

[0056] In another preferred embodiment, the ester solvent is selected from the group consisting of ethyl acetate.

[0057] In another preferred embodiment, the alcohol is methanol, and the reaction is carried out under the following conditions:

[0058] a) Dissolve palladium acetate, phosphine ligand and acid in methanol or a mixture of solvents with optional solvents;

[0059] b) Acetylene is introduced into the reactor, followed by carbon monoxide to carry out the reaction, wherein the reaction is carried out at room temperature to 120°C;

[0060] c) End the reaction and separate the product.

[0061] In another preferred embodiment, the alcohol is ethanol, and the reaction is carried out under the following conditions:

[0062] a) Dissolve palladium acetate, phosphine ligand and acid in ethanol or a mixture of solvents with optional solvents;

[0063] b) Acetylene is introduced into the reactor, followed by carbon monoxide to carry out the reaction, wherein the reaction is carried out at room temperature to 120°C;

[0064] c) End the reaction and separate the product.

[0065] In another preferred embodiment, the alcohol is butanol, and the reaction is carried out under the following conditions:

[0066] a) Dissolve palladium acetate, phosphine ligand, and acid in butanol or a mixture of butanol and optional solvents.

[0067] b) Acetylene is introduced into the reactor, followed by carbon monoxide to carry out the reaction, wherein the reaction is carried out at room temperature to 120°C;

[0068] c) End the reaction and separate the product.

[0069] In another preferred embodiment, the alcohol is octanol, and the reaction is carried out under the following conditions:

[0070] a) Dissolve palladium acetate, phosphine ligand, and acid in octanol or a mixture thereof with an optional solvent.

[0071] b) Acetylene is introduced into the reactor, followed by carbon monoxide to carry out the reaction, wherein the reaction is carried out at room temperature to 120°C;

[0072] c) End the reaction and separate the product.

[0073] 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

[0074] Based on long-term and in-depth research, the inventors have prepared a series of novel phosphine ligands and a method for synthesizing acrylates by acetylene carbonylation based on these ligands. This method can improve the catalytic efficiency of the acetylene carbonylation reaction, increase the conversion rate of acetylene and the product selectivity, and the reaction conditions are mild and the operation is simple. Based on the above findings, the inventors completed this invention.

[0075] definition

[0076] In this invention, "room temperature" refers to 10–30°C.

[0077] 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).

[0078] 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).

[0079] 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 C10 is preferred. 1-10 alkoxy groups (e.g., C) 1-8 alkoxy, C 1-6 alkoxy, C 1-4 (alkoxy group).

[0080] 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).

[0081] Unless otherwise specified, in this invention, "heteroaryl" refers to a group having 5-30 (preferably 5-20, more preferably 5-14) ring atoms (the ring atoms may be carbon atoms or heteroatoms) of 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 a 5-15 member heteroaryl, more preferably a 5-9 member heteroaryl.

[0082] 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.

[0083] The reagents and raw materials used in this invention are all commercially available.

[0084] 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.

[0085] Example 1: Preparation of the ligand shown in Formula I using L1 as an example.

[0086]

[0087] In a 100 mL three-necked flask equipped with a thermometer, magnetic stirrer, and reflux condenser, dibromide II (10 mmol) was dissolved in 50 mL of dry tetrahydrofuran. The solution was cooled to -78 °C, and 25 mL of n-butyllithium (in 1.6 M hexane) was added using a syringe. After stirring at low temperature for 3 hours, 20 mmol of phosphine chloride dissolved in 20 mL of dry tetrahydrofuran was added dropwise. The mixture was allowed to return to room temperature and reacted overnight. After the reaction was complete, the reaction was quenched with 2 mL of degassed water, concentrated, and the solvent removed. The mixture was then extracted with diethyl ether, separated, dried over anhydrous magnesium sulfate, and the ether removed. Recrystallization from methanol yielded a white or pale yellow solid powder.

[0088] Some ligand data are as follows:

[0089]

[0090] 1 H NMR (400MHz, CDCl3) δ8.61–8.46(m,2H),7.70–7.61(m,4H),7.40–7.21(m,7H),6.52-6.42(m,2H),2.05–1.98(m,6H),1.80–1.71(m,24H).

[0091]

[0092] 1 H NMR (400MHz, CDCl3) δ8.75–8.68(m,4H),7.73–7.61(m,4H),7.38–7.25(m,3H),6.53-6.41(m,2H),1.18–1.10(m,18H).

[0093]

[0094] 1HNMR(400MHz,CDCl3)δ8.79–8.70(m,4H),8.42((d,J=7.6Hz,1H),8.34(d,J=7.6Hz,1H),7.83–7.38(m,6H),7.06–7.00(m,1H),1.18–1.10(m,18H).

[0095]

[0096] 1 H NMR(400MHz,CDCl3)δ8.76–8.68(m,4H),7.65–7.13(m,8H),1.16–1.07(m,18H).

[0097]

[0098] 1 H NMR(400MHz,CDCl3)δ8.76–8.68(m,4H),7.65–7.13(m,8H),1.16–1.07(m,18H).

[0099]

[0100] 1 H NMR(400MHz,CDCl3)δ8.85–8.75(m,4H),7.80–7.56(m,6H),7.38–7.35(m,1H),7.13–7.10(m,1H),1.21–1.08(m,18H).

[0101]

[0102] 1 H NMR(400MHz,CDCl3)δ8.85–8.75(m,4H),7.75–7.40(m,6H),7.18–7.15(m,1H),6.92–6.89(m,1H),1.18–1.08(m,18H).

[0103]

[0104] 1 H NMR(400MHz,CDCl3)δ8.90–8.73(m,4H),7.82–7.50(m,6H),7.36–7.32(m,1H),6.61–6.58(m,1H),1.18–1.06(m,18H).

[0105]

[0106] 1 H NMR(400MHz,CDCl3)δ8.79–8.65(m,4H),7.95–7.90(m,2H),7.78–7.59(m,4H),7.39–7.28(m,3H),6.88–6.80(m,2H),1.17–1.05(m,18H).

[0107]

[0108] 1 H NMR(400MHz,CDCl3)δ8.90–8.75(m,4H),7.98–7.34(m,8H),1.20–1.06(m,18H).

[0109]

[0110] 1 H NMR(400MHz,CDCl3)δ8.86–8.71(m,4H),8.51–8.49(m,1H),7.68–7.15(m,9H),1.20–1.06(m,18H).

[0111]

[0112] 1 H NMR(400MHz,CDCl3)δ7.75–7.68(m,2H),7.40–7.21(m,5H),6.48–6.41(m,2H),6.21–6.12(m,4H),3.62–3.59(m,6H),1.20–1.06(m,18H).

[0113]

[0114] 1 H NMR(400MHz,CDCl3)δ7.85–7.70(m,4H),7.40–7.26(m,3H),6.65–6.60(m,2H),6.46–6.40(m,2H),3.95–3.90(m,6H),1.20–1.06(m,18H).

[0115]

[0116] 1H NMR(400MHz,CDCl3)δ8.21(s,1H),7.76–7.70(m,2H),7.34–7.29(m,3H),6.52–6.47(m,2H),3.85–3.80(m,6H),1.18–1.09(m,18H).

[0117]

[0118] 1 H NMR(400MHz,CDCl3)δ8.92–8.76(m,6H),7.73–7.68(m,2H),7.40–7.31(m,3H),6.52–6.47(m,2H),1.16–1.07(m,18H).

[0119]

[0120] 1 H NMR(400MHz,CDCl3)δ7.75–7.52(m,4H),7.40–7.31(m,3H),7.12–7.00(m,4H),6.54–6.48(m,2H),1.16–1.07(m,18H).

[0121]

[0122] 1 H NMR(400MHz,CDCl3)δ7.85–7.70(m,4H),7.40–7.29(m,3H),6.60–6.43(m,6H),1.18–1.07(m,18H).

[0123]

[0124] 1 H NMR(400MHz,CDCl3)δ8.87–8.83(m,4H),7.66–7.34(m,4H),7.00–6.87(m,3H),3.85–3.83(m,3H),1.16–1.06(m,18H).

[0125]

[0126] 1H NMR (400MHz, CDCl3) δ8.87–8.83(m,4H),7.65–7.53(m,3H),7.28–7.18(m,3H),6.55–6.49(m,2H),2.12–2.08(m,3H),1.16–1.06(m,18H).

[0127]

[0128] 1 H NMR (400MHz, CDCl3) δ8.47–8.43(m,2H),7.68–7.25(m,10H),6.48–6.44(m,2H),1.20–1.11(m,18H),-0.08–-0.12(m,9H).

[0129] Example 2

[0130] Palladium acetate Pd(OAc)₂ (2.2 mg, 0.01 mmol), bisphosphine ligand L1 (12.6 mg, 0.02 mmol), methanesulfonic acid (6.5 μL, 0.10 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Acetylene gas was then displaced, and the autoclave was purged with 62 mmol of acetylene gas through a flow meter while cooling. Carbon monoxide was then introduced until the pressure inside the autoclave reached 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 5 hours. After the reaction was complete, the temperature was lowered, and NMR analysis revealed a methyl acrylate yield of 78% with a selectivity greater than 90%.

[0131] Example 3

[0132] Palladium acetate Pd(OAc)₂ (0.2 mg, 0.001 mmol), bisphosphine ligand L₂ (0.9 mg, 0.002 mmol), methanesulfonic acid (6.5 μL, 0.10 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Acetylene gas was displaced, and acetylene gas (62 mmol) was introduced through a flow meter while cooling. Then, carbon monoxide was introduced until the pressure inside the autoclave reached 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 8 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed that the yield of methyl acrylate was 85%, with a selectivity greater than 90%.

[0133] Example 4

[0134] To a 300 mL Parr autoclave, under nitrogen protection, palladium trifluoroacetate Pd(OTFA)₂ (4.0 mg, 0.01 mmol), bisphosphine ligand L4 (9.3 mg, 0.02 mmol), methanesulfonic acid (6.5 μL, 0.10 mmol), methanol (10 mL), and a stir bar were added to displace acetylene gas. The autoclave was then purged with acetylene gas (62 mmol) through a flow meter while cooling, followed by carbon monoxide purging until the pressure reached 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 5 hours. After the reaction was complete, the temperature was lowered, and NMR analysis revealed a methyl acrylate yield of 80% and a selectivity greater than 90%.

[0135] Example 5

[0136] To a 300 mL Parr autoclave under nitrogen protection, palladium pentavalerate Pd(OPiv)₂ (3.1 mg, 0.01 mmol), bisphosphine ligand L5 (18.6 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), methanol (10 mL), and a stir bar were added to displace acetylene gas. The autoclave was then purged with acetylene gas (100 mmol) through a flow meter while cooling, followed by carbon monoxide purging until the pressure reached 6 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 revealed a methyl acrylate yield of 85% with a selectivity greater than 90%.

[0137] Example 6

[0138] In a 300 mL Parr autoclave under nitrogen protection, tris(dibenzylacetone)palladium Pd2(dba)3 (4.6 mg, 0.005 mmol), bisphosphine ligand L6 (9.8 mg, 0.02 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), ethanol (20 mL), and a stir bar were added to displace acetylene gas. The autoclave was then purged with acetylene gas (100 mmol) through a flow meter while cooling, followed by carbon monoxide purging until the pressure reached 6 MPa. The mixture was rapidly heated to 120 °C and stirred for 5 hours. After the reaction was complete, the temperature was lowered, and NMR analysis revealed a yield of 68% ethyl acrylate with a selectivity greater than 90%.

[0139] Example 7

[0140] To a 300 mL Parr autoclave under nitrogen protection, add bis(dibenzylacetone)palladium Pd(dba)2 (5.7 mg, 0.01 mmol), bisphosphine ligand L8 (19.0 mg, 0.04 mmol), trifluoromethanesulfonic acid (14.2 μL, 0.16 mmol), butanol (10 mL), tetrahydrofuran (10 mL), and a stir bar. Replace the acetylene gas with the stirred tank. Under cooling, purge with acetylene gas (62 mmol) through a flow meter, then purge with carbon monoxide until the pressure inside the autoclave reaches 4 MPa. Rapidly heat to 120 °C and stir for 6 hours. After the reaction is complete, cool and analyze by NMR to obtain a butyl acrylate yield of 87% with a selectivity greater than 90%.

[0141] Example 8

[0142] In a 300 mL Parr autoclave under nitrogen protection, palladium chloride (PdCl2, 1.8 mg, 0.01 mmol), bisphosphine ligand L9, 10.5 mg, 0.02 mmol, dodecyl sulfonic acid, 26.1 mg, 0.08 mmol, methanol (20 mL), and a stir bar were added to displace acetylene gas. The autoclave was then purged with acetylene gas (62 mmol) through a flow meter while cooling, followed by carbon monoxide purging until the pressure reached 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 revealed a methyl acrylate yield of 78% with a selectivity greater than 90%.

[0143] Example 9

[0144] To a 300 mL Parr autoclave under nitrogen protection, palladium hexafluoroacetylacetonate Pd(hfacac)₂ (3.1 mg, 0.01 mmol), bisphosphine ligand L10 (19.7 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), octanol (10 mL), n-hexane (10 mL), and a stir bar were added to displace acetylene gas. The autoclave was then purged with acetylene gas (62 mmol) through a flow meter while cooling, followed by carbon monoxide purging until the pressure reached 4 MPa. The reaction was stirred at room temperature for 24 hours. After the reaction was complete, the temperature was lowered, and NMR analysis revealed a yield of 73% for octyl acrylate with a selectivity greater than 90%.

[0145] Example 10

[0146] To a 300 mL Parr autoclave under nitrogen protection, palladium tetraacetonitrile tetrafluoroborate Pd(CH3CN)4(BF4)2 (4.4 mg, 0.01 mmol), bisphosphine ligand L11 (21.0 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), methanol (10 mL), 1,4-dioxane (10 mL), and a stir bar were added to displace acetylene gas. The autoclave was then purged with acetylene gas (62 mmol) through a flow meter while cooling, followed by carbon monoxide purging until the pressure reached 4 MPa. The temperature was rapidly increased to 120 °C, and the reaction was stirred for 6 hours. After the reaction was complete, the temperature was lowered, and NMR analysis revealed a methyl acrylate yield of 78% with a selectivity greater than 90%.

[0147] Example 11

[0148] Pd(OAc)₂ (11.2 mg, 0.05 mmol), bisphosphine ligand L12 (19.1 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), butanol (10 mL), tetrahydrofuran (10 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Acetylene gas was then displaced, and the autoclave was purged with 62 mmol of acetylene gas through a flow meter while cooling. Carbon monoxide was then introduced until the pressure inside the autoclave reached 4 MPa. The mixture was rapidly heated to 120 °C and stirred for 8 hours. After the reaction was complete, the temperature was lowered, and NMR analysis revealed a butyl acrylate yield of 75% with a selectivity greater than 90%.

[0149] Example 12

[0150] Pd(OAc)₂ (2.2 mg, 0.01 mmol), bisphosphine ligand L13 (9.5 mg, 0.02 mmol), p-toluenesulfonic acid (17.5 mg, 0.10 mmol), methanol (10 mL), tetrahydrofuran (10 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Acetylene gas was then displaced, and the autoclave was purged with 100 mmol of acetylene gas through a flow meter while cooling. Carbon monoxide was then introduced until the pressure inside the autoclave reached 6 MPa. The mixture was rapidly heated to 120 °C and stirred for 5 hours. After the reaction was complete, the temperature was lowered, and NMR analysis revealed a yield of methyl acrylate of 64% with a selectivity greater than 90%.

[0151] Example 13

[0152] Pd(OAc)₂ (2.2 mg, 0.01 mmol), bisphosphine ligand L14 (9.6 mg, 0.02 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), methanol (10 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Acetylene gas was then displaced, and the autoclave was purged with 100 mmol of acetylene gas through a flow meter while cooling. Carbon monoxide was then introduced until the pressure inside the autoclave reached 6 MPa. The mixture was rapidly heated to 120 °C and stirred for 5 hours. After the reaction was complete, the temperature was lowered, and NMR analysis revealed a methyl acrylate yield of 67% with a selectivity greater than 90%.

[0153] Example 14

[0154] Pd(OAc)₂ (2.24 mg, 0.01 mmol), bisphosphine ligand L15 (9.5 mg, 0.02 mmol), trifluoroacetic acid (12 μL, 0.16 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Acetylene gas was then displaced, and the autoclave was purged with 100 mmol of acetylene gas through a flow meter while cooling. Carbon monoxide was then introduced until the pressure inside the autoclave reached 6 MPa. The mixture was rapidly heated to 120 °C and stirred for 5 hours. After the reaction, NMR analysis showed a yield of methyl acrylate of 82% and a selectivity greater than 90%.

[0155] Example 15

[0156] Pd(OAc)₂ (2.24 mg, 0.01 mmol), bisphosphine ligand L16 (9.7 mg, 0.02 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Acetylene gas was then displaced, and the autoclave was purged with 100 mmol of acetylene gas through a flow meter while cooling. Carbon monoxide was then introduced until the pressure inside the autoclave reached 6 MPa. The mixture was rapidly heated to 100 °C and stirred for 5 hours. After the reaction, NMR analysis showed a yield of methyl acrylate of 63% and a selectivity greater than 90%.

[0157] Example 16

[0158] Pd(OAc)₂ (2.2 mg, 0.01 mmol), bisphosphine ligand L17 (18.0 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Acetylene gas was then displaced, and the autoclave was purged with 100 mmol of acetylene gas through a flow meter while cooling. Carbon monoxide was then introduced until the pressure inside the autoclave reached 6 MPa. The mixture was rapidly heated to 60 °C and stirred for 8 hours. After the reaction was complete, the temperature was lowered, and NMR analysis revealed a methyl acrylate yield of 58% with a selectivity greater than 90%.

[0159] Example 17

[0160] Pd(OAc)₂ (2.2 mg, 0.01 mmol), bisphosphine ligand L18 (20.2 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Acetylene gas was then displaced, and the autoclave was purged with 100 mmol of acetylene gas through a flow meter while cooling. Carbon monoxide was then introduced until the pressure inside the autoclave reached 6 MPa. The mixture was rapidly heated to 120 °C and stirred for 5 hours. After the reaction was complete, the temperature was lowered, and NMR analysis revealed a yield of methyl acrylate of 84% with a selectivity greater than 90%.

[0161] Example 18

[0162] Pd(OAc)₂ (2.2 mg, 0.01 mmol), bisphosphine ligand L19 (19.6 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Acetylene gas was then displaced, and the autoclave was purged with 100 mmol of acetylene gas through a flow meter while cooling. Carbon monoxide was then introduced until the pressure inside the autoclave reached 6 MPa. The reaction was stirred at room temperature for 10 hours. After the reaction, NMR analysis showed a yield of methyl acrylate of 81% and a selectivity greater than 90%.

[0163] Example 19

[0164] Pd(OAc)₂ (0.2 mg, 0.001 mmol), bisphosphine ligand L20 (2.0 mg, 0.004 mmol), methanesulfonic acid (1.0 μL, 0.016 mmol), methanol (20 mL), and a stir bar were added to a 300 mL Parr autoclave under nitrogen protection. Acetylene gas was displaced, and acetylene gas (100 mmol) was introduced through a flow meter while cooling. Then, carbon monoxide was introduced until the pressure inside the autoclave reached 6 MPa. The mixture was rapidly heated to 100 °C and stirred for 8 hours. After the reaction was complete, the temperature was lowered, and NMR analysis showed that the yield of methyl acrylate was 81%, with a selectivity greater than 90%.

[0165] The phosphine ligands of the present invention can produce acrylate products in high yields (>55%, >80% in the best example) with good selectivity when used for catalytic preparation of acrylates, and therefore have potential industrial applications.

[0166] Furthermore, the phosphine ligands of the present invention exhibit good catalytic conversion rates, thus enabling the conversion to be achieved at low concentrations (<10). -4 Equivalent, preferably <10 -5 Equivalent, preferably <10 -6 The catalytic reaction is completed in equivalent quantities.

[0167] 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 phosphine ligand, characterized in that, The ligands have structures selected from those shown in Formula I: in, R 1 and R 4 Each is independently selected from the group consisting of: methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, isobutyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, or adamantyl; R 2 and R 3 Each is independently selected from the group consisting of: substituted or unsubstituted pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, imidazolyl, pyrazolyl, thiophene, furanyl, thiazolyl, and triazolyl; A is a 5-10 member heteroaryl group, wherein the heteroatom in the heteroaryl group is one or more of O, N, and S, and may be the same or different; R 5 Each is an independent substituent located on the corresponding ring and selected from the following groups: H, C 1-10 Alkyl, C 1-10 Alkoxy, trialkylsilyl, wherein the alkyl group in the trialkylsilyl group is C 1-4 alkyl; The substitution refers to the substitution of one or more hydrogen atoms on a group by a substituent selected from the group consisting of: C 1-10 alkyl; And the compound is not .

2. The ligand as described in claim 1, characterized in that, In the ligands described, R 1 and R 4 Each is independently selected from the group consisting of tert-butyl or adamantyl; R 2 and R 3 Each of the following groups is selected independently: pyridyl, pyrazinyl, pyrimidinyl, pyrazolyl, thiophenyl, furanyl, and triazolyl.

3. The ligand as described in claim 1, characterized in that, The ligands are selected from the following group: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 。 4. A method for synthesizing acrylate by palladium-catalyzed acetylene carbonylation, characterized in that, The method includes the following steps: a) In a reaction vessel, a palladium catalyst, a phosphine ligand, and an acid are dissolved in an alcohol and, optionally, a solvent; wherein the phosphine ligand is the phosphine ligand of formula I as described in claim 1, or ; b) Introduce acetylene into the reactor, followed by carbon monoxide, to carry out the reaction; c) End the reaction and separate the product.

5. The method as described in claim 4, characterized in that, The amount of the phosphine ligand is 0.00001 to 10% molar equivalent of the acetylene.

6. The method as described in claim 4, characterized in that, The alcohol is C 1-12 Alkyl alcohols.

7. The method as described in claim 6, characterized in that, The alcohol is selected from the group consisting of methanol, ethanol, propanol, butanol, octanol, or combinations thereof.

8. The method as described in claim 4, 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, palladium diacetonitrile dichloride, palladium dibenzonitrile dichloride, or combinations thereof.

9. The method as described in claim 4, characterized in that, 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, and arylsulfonic acid, wherein the alkyl group is C. 1-12 Alkyl group, wherein the aryl group is C 6-10 Aryl.

10. The method as described in claim 4, 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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