CN118530278A - Phosphine ligands and their application in the synthesis of acrylic acid esters by carbonylation of acetylene - Google Patents

Abstract

The present invention relates to a phosphine ligand and its application in the synthesis of acrylic acid ester by carbonylation of acetylene. The phosphine ligand of the present invention is shown in Formula I. The phosphine ligand of the present invention can be combined with a palladium catalyst to jointly catalyze the carbonylation reaction of acetylene to synthesize acrylic acid ester. The method has the characteristics of high catalytic efficiency, high product yield, high selectivity, simple operation, etc.

Description

Phosphine ligands and their application in the synthesis of acrylic acid esters by carbonylation of acetylene

Technical Field

The invention relates to a phosphine ligand and application thereof in the synthesis of acrylic acid ester by carbonylation of acetylene.

Background Art

Acrylic acid ester is an important chemical raw material, mainly used for synthetic resin monomers, and is widely used in coatings, adhesives, textiles, rubber and other industries. Driven by the construction, textile and packaging industries, my country's consumption of acrylic acid (ester) continues 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 routes that replace petrochemical products as raw materials has received widespread attention. Therefore, the synthesis of acrylic acid (ester) by acetylene carbonylation, a non-petroleum route, will be more competitive and is one of the technical development trends for the production of acrylic acid (ester).

Acetylene carbonylation to acrylic acid was first invented by German W. Reppe (US2653969). In the presence of nickel tetracarbonyl, acetylene-carbon monoxide-water (alcohol) was converted into acrylic acid (ester). This reaction requires high conditions (>150°C, 1-3 MPa), serious catalyst loss, and high toxicity. After being improved by Rohmd-Hass, Dow-Badische, and BASF, it was used in industrial production (US2582911, US2964558, US3060228, US2881205, US2845451, US2886591, US2883418). So far, there are no less than hundreds of catalysts reported for this reaction, but they are basically based on nickel halides or copper halides. Although these halogen-containing catalysts have good yields and selectivities, they have problems such as long reaction time, carbon deposition during the reaction, and severe equipment corrosion.

Alper et al. found that palladium acetate can achieve the hydrocarbonylation reaction 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 phosphine ligands are very important for reaction activity and selectivity. In 2009, the CN101768070A patent disclosed the use of palladium acetate as a catalyst, sulfonic acid as an auxiliary agent, and 2-pyridyldiphenylphosphine as a ligand to achieve the carbonylation of acetylene to synthesize acrylic acid under mild conditions (40°C, 5MPa), but the acetylene conversion rate of this method is not high (<42%). In 2015, Zhou Qilin et al. used the Pd(II)/Xantphos catalytic system and formic acid as a carbonyl source to achieve the carbonylation reaction of acetylene to synthesize acrylic acid, and the highest TON of the reaction reached 140 (Angew.Chem.Int.Ed.2015, 54, 6302). Although the conditions of the palladium catalytic system are relatively mild and the reaction selectivity is good, the current catalyst activity is not high enough, that is, the catalytic conversion number is low, which affects the industrial application of the process.

Summary of the invention

The object of the present invention is to provide a catalyst for preparing acrylic acid esters by carbonylation of acetylene.

Another object of the present invention is to provide a process for preparing acrylic acid ester (such as methyl acrylate, ethyl acrylate, butyl acrylate or octyl acrylate).

In a first aspect of the present invention, a phosphine ligand for acetylene-catalyzed preparation of acrylic acid ester is provided, wherein the ligand has a structure selected from the group consisting of:

The ligand has a structure selected from the group consisting of:

in,

R ¹ is selected from the following group: substituted or unsubstituted C _1-10 alkyl, substituted or unsubstituted C _3-12 cycloalkyl (adamantyl), substituted or unsubstituted C _6-30 aryl;

^R2 is selected from the group consisting of substituted or unsubstituted 5-20 membered heteroaryl;

^R3 is hydrogen, substituted or unsubstituted _C1-10 alkyl, substituted or unsubstituted _C1-10 alkoxy, substituted or unsubstituted _C2-10 ester, cyano, COOH, benzenesulfonyl, trialkylsilyl (wherein the alkyl is _C1-4 alkyl), nitro, substituted or unsubstituted _C6-30 aryl, substituted or unsubstituted 5-30 membered heteroaryl; or two ^R3 located on adjacent carbon atoms and the carbon atom to which they are connected together constitute a group selected from the group consisting of _C6-10 aryl, 5-12 membered heteroaryl;

In the ligand, A is a substituted or unsubstituted C _1-4 alkylene group, or the A and Together in, is the linking site connected to P;

Wherein, R ⁴ is one or more substituents located on the corresponding ring selected from the group consisting of H, C _1-10 alkyl, C _1-10 alkoxy, C _2-10 ester, cyano, COOH, benzenesulfonyl, trialkylsilyl (wherein the alkyl is C _1-4 alkyl), nitro, C _6-30 aryl, 5-30 membered heteroaryl; or together with R ³ and one or more ring atoms on the pyridine ring, forms a 5-7 membered carbocyclic or heterocyclic ring;

Unless otherwise specified, the substitution refers to that one or more hydrogen atoms on the group are replaced by a substituent selected from the group consisting of C _1-10 alkyl, C _1-10 alkoxy, C _2-10 ester, cyano, COOH, benzenesulfonyl, trialkylsilyl (wherein the alkyl is C _1-4 alkyl), nitro, C _6-30 aryl, and 5-30 membered heteroaryl.

In another preferred embodiment, in the ligand, A is CH ₂ or or the A and Together in, is the linking site connected to P;

Wherein, R ⁴ is one or more substituents located on the corresponding ring and selected from the following group: H, C _1-10 alkyl, C _1-10 alkoxy, C _2-10 ester, cyano, COOH, benzenesulfonyl, trialkylsilyl (wherein the alkyl is C _1-4 alkyl).

In another preferred embodiment, in the ligand,

R ¹ is selected from the following group: substituted or unsubstituted C _1-10 alkyl, substituted or unsubstituted C _3-10 cycloalkyl;

^R2 is selected from the group consisting of substituted or unsubstituted 5-10 membered heteroaryl;

R ³ is hydrogen, C _1-10 alkyl, C _1-10 alkoxy, C _2-10 ester, cyano, trialkylsilyl (wherein the alkyl is C _1-4 alkyl), nitro, -CH(Ph) ₂ , C _6-30 aryl, 5-10 membered heteroaryl.

In another preferred embodiment, in the ligand,

^R1 is 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 is selected from the group consisting of pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrrolyl, imidazolyl, pyrazolyl, thienyl, furanyl, thiazolyl, triazolyl; and said R ² may be optionally substituted by one or more substituents selected from the group consisting of C _1-4 alkyl;

R ³ is selected from the group consisting of methyl, n-propyl, isopropyl, tert-butyl, methoxy, cyano, COOH, -CH(Ph) ₂ , benzenesulfonyl, and trimethylsilyl.

In another preferred embodiment, the ligand is selected from the following group:

In a second aspect of the present invention, there is provided a method for synthesizing acrylic acid ester by carbonylation of acetylene catalyzed by palladium, the method comprising the steps of:

a) in a reaction vessel, dissolving a palladium catalyst, a phosphine ligand and an acid in an alcohol and an optional solvent; wherein the phosphine ligand is a phosphine ligand of formula I as described in the second aspect;

b) introducing acetylene into the kettle and then introducing carbon monoxide to react;

c) End the reaction and separate the product.

In another preferred embodiment, the reaction kettle is an autoclave.

In another preferred embodiment, the amount of the phosphine ligand used is 0.00001 to 10% molar equivalent of the acetylene, and more preferably 0.001 to 1% molar equivalent.

In another preferred embodiment, the reaction temperature is 0-200°C, preferably 60-120°C.

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.

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

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

In another preferred embodiment, the alcohol is a C _1-12 alkyl alcohol; preferably, the alcohol is selected from the following group: methanol, ethanol, propanol, butanol, octanol, or a combination thereof.

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

In another preferred embodiment, the palladium catalyst is selected from the following group: palladium acetate, palladium trifluoroacetate, palladium pentanoate, palladium tetraacetonitrile tetrafluoroborate, palladium hexafluoroacetylacetonate, palladium di(acetylacetone), palladium tetraacetonitrile trifluoromethanesulfonate, palladium pivalate, bis(dibenzylideneacetone)palladium, tris(dibenzylideneacetone)dipalladium, palladium chloride, diacetonitrile palladium dichloride, dibenzonitrile palladium dichloride, or a combination thereof.

In another preferred embodiment, the palladium catalyst is selected from the group consisting of palladium acetate, palladium trifluoroacetate, palladium pentanoate, tris(dibenzylideneacetone)dipalladium, palladium chloride, diacetonitrile palladium dichloride, or a combination thereof.

In another preferred embodiment, the amount of the palladium catalyst used is 0.00001 to 10% molar equivalent of the acetylene, and more preferably 0.0001 to 1% molar equivalent.

In the reaction, when the phosphine ligand is a nitrogen phosphine ligand (ie, a 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 1:5.

In another preferred embodiment, the acid is selected from the following group: perchloric acid, sulfuric acid, phosphoric acid, sulfonic acid, alkylphosphonic acid, alkylsulfonic acid, alkylcarboxylic acid, perfluoroalkylsulfonic acid, perfluoroalkylcarboxylic acid (wherein the alkyl is C _1-12 alkyl) or arylsulfonic acid (wherein the aryl is C _6-10 aryl).

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, dodecylsulfonic acid, sulfuric acid, sulfonic acid, formic acid and trifluoroacetic acid.

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

In another preferred embodiment, the solvent is selected from the following group: alkane solvents, substituted aromatic solvents, ether solvents, ketone solvents, nitrile solvents, ester solvents, or a combination thereof.

In another preferred embodiment, the alkane solvent is selected from the following group: n-hexane, cyclohexane, or a combination thereof.

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

In another preferred embodiment, the ether solvent is selected from the following group: tetrahydrofuran, diethyl ether, methyl tert-butyl ether, ethyl tert-butyl ether, anisole, ethylene glycol dimethyl ether, 1,4-dioxane, or a combination thereof.

In another preferred embodiment, the ketone solvent is selected from the following group: acetone.

In another preferred embodiment, the nitrile solvent is selected from the following group: acetonitrile, propionitrile, benzonitrile, or a combination thereof.

In another preferred embodiment, the ester solvent is selected from the following group: ethyl acetate.

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

a) dissolving palladium acetate, a phosphine ligand and an acid in methanol or a mixed solvent with an optional solvent;

b) introducing acetylene into the kettle and then introducing carbon monoxide to react, wherein the reaction is carried out at room temperature to 120° C.;

c) End the reaction and separate the product.

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

a) dissolving palladium acetate, a phosphine ligand and an acid in ethanol or a mixed solvent with an optional solvent;

b) introducing acetylene into the kettle and then introducing carbon monoxide to react, wherein the reaction is carried out at room temperature to 120° C.;

c) End the reaction and separate the product.

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

a) dissolving palladium acetate, phosphine ligand and acid in butanol or a mixed solvent with an optional solvent,

b) introducing acetylene into the kettle and then introducing carbon monoxide to react, wherein the reaction is carried out at room temperature to 120° C.;

c) End the reaction and separate the product.

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

a) dissolving palladium acetate, phosphine ligand and acid in octanol or a mixed solvent with an optional solvent,

b) introducing acetylene into the kettle and then introducing carbon monoxide to react, wherein the reaction is carried out at room temperature to 120° C.;

c) End the reaction and separate the product.

It should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described below (such as embodiments) can be combined with each other to form a new or preferred technical solution. Due to space limitations, they will not be described one by one here.

DETAILED DESCRIPTION

Based on long-term and in-depth research, the inventors have prepared a series of novel phosphine ligands and a method for synthesizing acrylic esters by carbonylation of acetylene based on the ligands. The method can improve the catalytic efficiency of the carbonylation reaction of acetylene, improve the conversion rate of acetylene and product selectivity, and the reaction conditions are mild and the operation is simple. Based on the above findings, the inventors have completed the present invention.

definition

In the present invention, "room temperature" means 10 to 30°C.

In the present invention, the term "alkyl" refers to a linear or branched saturated hydrocarbon group, preferably a C _1-10 alkyl group (eg, a C _1-8 alkyl group, a C _1-6 alkyl group, a C _1-4 alkyl group).

In the present invention, the term "cycloalkyl" refers to a saturated monocyclic or carbon ring substituent containing a fused, bridged or spiro polycyclic system, preferably a C _3-8 cycloalkyl (eg C _3-6 cycloalkyl).

In the present invention, the term "alkoxy" refers to a cyclic or non-cyclic alkyl group connected by an oxygen bridge, and the definitions of alkyl and cycloalkyl are as described above, preferably a C _1-10 alkoxy group (e.g., a C _1-8 alkoxy group, a C _1-6 alkoxy group, a C _1-4 alkoxy group).

Unless otherwise specified, in the present 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 a _C6 - _C14 aryl group, and more preferably a _C6 - _C10 aryl group).

Unless otherwise specified, in the present invention, "heteroaryl" refers to a group having 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 a 5-15 membered heteroaryl, and more preferably a 5-9 membered heteroaryl.

Without violating the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

The reagents and raw materials used in the present invention are commercially available.

The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples without specifying specific conditions are usually based on conventional conditions or the conditions recommended by the manufacturer. Unless otherwise stated, percentages and parts are calculated by weight.

Example 1 Preparation of the ligand represented by formula I using L1 as an example

In a 100mL three-necked flask equipped with a thermometer, a magnetic stirrer and a reflux cooler, bromide II (10mmol) was dissolved in 50mL dry tetrahydrofuran. The temperature was lowered to -78°C, and n-butyl lithium (12mL, 1.6M n-hexane solution) was added by injection. After stirring at low temperature for 3 hours, chlorophosphine (10mmol) dissolved in 10mL dry tetrahydrofuran was then added dropwise, and the mixture was naturally returned to room temperature to react overnight. After the reaction was completed, 2mL of degassed water was added to quench the reaction, the mixture was concentrated, the solvent was removed, oxygen-free water was added, ether was extracted, the liquids were separated, and after drying over anhydrous magnesium sulfate, the ether was removed and the obtained sample was recrystallized in methanol to obtain a white or light yellow solid powder.

Some ligand data are as follows:

¹ H NMR (400MHz, CDCl ₃ ) δ8.58(d,J＝7.6Hz,2H),8.42(d,J＝8.0Hz,1H),8.12(d,J＝7.6Hz,1H),7.53–7.47 (m,3H),7.34–7.30(m,2H),7.14–7.11(m,1H),7.00–6.97(m,1H),1.72–1.68(m,1H),0.98(d,J＝6.8Hz ,6H).

¹ H NMR (400MHz, CDCl ₃ ) δ8.63(d,J＝7.6Hz,2H),8.46(d,J＝8.0Hz,1H),8.12(d,J＝7.6Hz,1H),8.00(d ,J＝7.6Hz,1H),7.64–7.47(m,7H),7.34–7.30(m,1H),1.72–1.68(m,1H),1.01(d,J＝6.8Hz,6H).

¹ H NMR (400MHz, CDCl ₃ ) δ9.01(d,J＝7.6Hz,1H),8.71(d,J＝7.6Hz,2H),8.49(d,J＝7.6Hz,1H),8.09(d ,J＝7.6Hz,1H),7.83–7.67(m,4H),1.08(s,9H).

¹ H NMR (400 MHz, CDCl ₃ ) δ9.01 (d, J = 7.6 Hz, 1H), 8.71 (d, J = 7.6 Hz, 2H), 8.49 (d, J = 7.6 Hz, 1H), 8.09 ( d,J＝7.6 Hz,1H),7.83–7.67(m,4H),1.08(s,9H).

¹ H NMR (400 MHz, CDCl ₃ ) δ8.56 (d, J = 7.6 Hz, 1H), 8.17 (d, J = 7.6 Hz, 1H), 7.66–7.53 (m, 3H), 7.35–7.30 (m ,4H),6.87–6.78(m,2H),3.22–3.18(m,1H),1.28(d,J=7.2 Hz,6H),1.09(s,9H).

¹ H NMR (400 MHz, CDCl ₃ ) δ8.18 (d, J = 7.6 Hz, 1H), 7.52–7.49 (m, 2H), 7.35–7.30 (m, 2H), 7.02 (d, J = 7.2 Hz ,1H),6.81(d,J＝7.2 Hz,1H),3.68(s,3H),3.00(t,J＝7.2 Hz,2H),1.76–1.73(m,2H),1.08(s,9H) ,0.93(t,J=7.2 Hz,3H).

¹ H NMR (400 MHz, CDCl ₃ ) δ8.20 (d, J = 8.0 Hz, 1H), 7.52–7.49 (m, 2H), 7.35–7.26 (m, 3H), 7.13 (d, J = 7.2 Hz ,1H),6.82(d,J＝7.2 Hz,1H),6.20–6.17(m,2H),3.65(s,3H),3.35–3.30(m,1H),1.29(d,J＝7.2 Hz, 6H),1.07(s,9H).

¹ H NMR (400 MHz, CDCl ₃ ) δ8.15 (d, J = 7.6 Hz, 1H), 7.55–7.53 (m, 2H), 7.35–7.30 (m, 2H), 7.08–6.97 (m, 4H) ,6.82(d,J＝7.2 Hz,1H),3.39–3.36(m,1H),1.28(d,J＝7.2 Hz,6H),1.09(s,9H).

¹ H NMR (400 MHz, CDCl ₃ ) δ9.30 (s, 1H), 8.17 (d, J = 7.6 Hz, 1H), 8.02 (d, J = 7.6 Hz, 1H), 7.60–7.48 (m, 6H ),7.35–7.30(m,2H),7.01(d,J＝7.6 Hz,1H),6.82(d,J＝7.2 Hz,1H),3.37–3.33(m,1H),1.28(d,J＝ 7.2 Hz, 6H), 1.09 (s, 9H).

¹ H NMR (400 MHz, CDCl ₃ ) δ8.85–8.76 (m, 3H), 8.18 (d, J = 7.6 Hz, 1H), 7.55–7.50 (m, 2H), 7.34–7.29 (m, 2H) ,6.98(d,J＝7.6 Hz,1H),6.75(d,J＝7.2Hz,1H),3.37–3.33(m,1H),1.30(d,J＝7.2 Hz,6H),1.08(s, 9H).

¹ H NMR (400 MHz, CDCl ₃ ) δ8.55(d,J＝8.0 Hz,1H),8.15(d,J＝7.6 Hz,1H),8.02–7.97(m,2H),7.85–7.80(m ,1H),7.55–7.50(m,4H),7.34–7.29(m,2H),7.00(d,J＝7.6 Hz,1H),6.70(d,J＝7.2 Hz,1H),3.37–3.33( m,1H),1.27(d,J=7.2 Hz,6H),1.07(s,9H).

¹ H NMR (400 MHz, CDCl ₃ ) δ8.63 (d, J = 8.0 Hz, 2H), 8.13 (d, J = 7.6 Hz, 1H), 7.55–7.50 (m, 3H), 7.33–7.15 (m ,12H),7.00–6.95(m,2H),5.53(s,1H),2.03–1.98(m,3H),1.80–1.71(m,12H).

¹ H NMR (400 MHz, CDCl ₃ ) δ8.65 (d, J = 8.0 Hz, 2H), 8.17 (d, J = 7.6 Hz, 1H), 7.52–7.35 (m, 4H), 7.02–6.97 (m ,2H),3.98(s,3H),3.05(t,J＝7.2 Hz,2H),1.76–1.73(m,2H),1.08(s,9H),0.95(t,J＝7.2 Hz,3H) .

¹ H NMR (400 MHz, CDCl ₃ ) δ8.68 (d, J = 8.0 Hz, 2H), 8.15 (d, J = 7.6 Hz, 1H), 7.60–7.30 (m, 4H), 7.12 (d, J ＝7.6 Hz,1H),6.72(d,J＝7.6 Hz,1H),3.02(t,J＝7.2 Hz,2H),1.76–1.70(m,2H),1.40(s,9H),1.08(s ,9H),0.95(t,J=7.2 Hz,3H).

¹ H NMR (400 MHz, CDCl ₃ ) δ8.65 (d, J = 7.6 Hz, 2H), 7.65–7.30 (m, 5H), 7.02 (d, J = 7.6 Hz, 1H), 6.81 (d, J ＝7.6 Hz,1H),3.02(t,J＝7.2 Hz,2H),1.76–1.70(m,2H),1.08(s,9H),0.96(t,J＝7.2 Hz,3H),0.12(s ,9H),.

¹ H NMR (400MHz, CDCl ₃ ) δ8.75 (d, J = 7.6Hz, 2H), 7.65–7.58 (m, 2H), 7.02–6.97 (m, 2H), 4.00–3.96 (m, 1H), 3.70–3.66(m,1H),3.02(t,J＝7.2Hz,2H),1.82–1.79(m,2H),1.06(s,9H),0.98(t,J＝7.2Hz,3H).

¹ H NMR (400MHz, CDCl ₃ ) δ8.73 (d, J = 7.6Hz, 2H), 7.60–7.53 (m, 2H), 7.06–7.00 (m, 2H), 4.03–3.97 (m, 1H), 3.74–3.69(m,1H),3.02(t,J＝7.2Hz,2H),2.03–1.98(m,3H),1.80–1.71(m,14H),0.98(t,J＝7.2Hz,3H) .

¹ H NMR (400MHz, CDCl ₃ ) δ7.57 (t, J＝7.6Hz, 1H), 7.46–7.38 (m, 3H), 7.18–7.14 (m, 3H), 7.02–6.98 (m, 2H), 6.88(d,J＝7.6Hz,1H),4.02–3.98(m,1H),3.72–3.68(m,1H),3.54(s,3H),3.45–3.42(m,1H),1.36(d, J＝7.2Hz,6H).

Example 2

Pd(OAc) ₂ (2.2 mg, 0.01 mmol), nitrogen phosphine ligand L1 (6.2 mg, 0.02 mmol), methanesulfonic acid (6.5 μL, 0.10 mmol), methanol (20 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (62 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave was 4 MPa. The temperature was quickly raised to 120°C and stirred for 5 hours. After the reaction was completed, the temperature was lowered, and the yield of methyl acrylate was 87% and the selectivity was greater than 90% by nuclear magnetic resonance.

Example 3

Pd(OAc) ₂ (2.2 mg, 0.01 mmol), nitrogen phosphine ligand L2 (7.1 mg, 0.02 mmol), methanesulfonic acid (6.5 μL, 0.10 mmol), methanol (20 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (62 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave reached 4 MPa. The temperature was quickly raised to 120°C and stirred for 5 hours. After the reaction was completed, the temperature was lowered, and the yield of methyl acrylate was 85% and the selectivity was greater than 90% by nuclear magnetic resonance.

Example 4

Pd(OAc) ₂ (2.2 mg, 0.01 mmol), nitrogen phosphine ligand L3 (5.9 mg, 0.02 mmol), methanesulfonic acid (6.5 μL, 0.10 mmol), methanol (10 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (62 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave was 4 MPa. The temperature was quickly raised to 120°C and stirred for 5 hours. After the reaction was completed, the temperature was lowered, and the yield of methyl acrylate was 64% by nuclear magnetic resonance, and the selectivity was greater than 90%.

Example 5

Pd(OAc) ₂ (2.2 mg, 0.01 mmol), nitrogen phosphine ligand L4 (14.5 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), methanol (10 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (100 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave reached 6 MPa. The temperature was quickly raised to 120°C and stirred for 6 hours. After the reaction was completed, the temperature was lowered, and the yield of methyl acrylate was 90% by nuclear magnetic resonance, and the selectivity was greater than 90%.

Example 6

Pd(OAc) ₂ (2.2 mg, 0.01 mmol), nitrogen phosphine ligand L5 (14.4 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), methanol (10 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (100 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave reached 6 MPa. The temperature was quickly raised to 120°C and stirred for 6 hours. After the reaction was completed, the temperature was lowered, and the yield of methyl acrylate was 85% and the selectivity was greater than 90% by nuclear magnetic resonance.

Example 7

Pd(OAc) ₂ (2.2 mg, 0.01 mmol), nitrogen phosphine ligand L6 (14.6 mg, 0.04 mmol), p-toluenesulfonic acid (17.2 mg, 0.10 mmol), methanol (10 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (100 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave reached 6 MPa. The temperature was quickly raised to 120°C and stirred for 5 hours. After the reaction was completed, the temperature was lowered, and the yield of methyl acrylate was 78% and the selectivity was greater than 90% by nuclear magnetic resonance.

Example 8

PdCl ₂ (1.8 mg, 0.01 mmol), nitrogen phosphine ligand L7 (14.5 mg, 0.04 mmol), trifluoromethanesulfonic acid (14.2 μL, 0.16 mmol), butanol (5 mL), tetrahydrofuran (10 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (62 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave reached 4 MPa. The temperature was quickly raised to 120°C and stirred for 6 hours. After the reaction was completed, the temperature was lowered, and the yield of butyl acrylate was 65% and the selectivity was greater than 90% by nuclear magnetic resonance.

Example 9

Pd(OAc) ₂ (2.2 mg, 0.01 mmol), nitrogen phosphine ligand L8 (7.3 mg, 0.02 mmol), dodecylsulfonic acid (26.1 mg, 0.08 mmol), methanol (20 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (62 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave was 4 MPa. The temperature was quickly raised to 120°C and stirred for 6 hours. After the reaction was completed, the temperature was lowered, and the yield of methyl acrylate was 60% and the selectivity was greater than 90% by nuclear magnetic resonance.

Example 10

Pd(OAc) ₂ (2.2 mg, 0.01 mmol), nitrogen phosphine ligand L9 (8.2 mg, 0.02 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), octanol (10 mL), n-hexane (10 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (62 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave was 4 MPa. The temperature was quickly raised to 120°C and stirred for 5 hours. After the reaction was completed, the temperature was lowered, and the yield of octyl acrylate was 81% and the selectivity was greater than 90% by nuclear magnetic resonance.

Embodiment 11

Pd(OAc) ₂ (2.2 mg, 0.01 mmol), nitrogen phosphine ligand L10 (7.3 mg, 0.02 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), methanol (20 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (62 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave reached 4 MPa. The temperature was quickly raised to 120°C and stirred for 5 hours. After the reaction was completed, the temperature was lowered, and the yield of octyl acrylate was 77% by nuclear magnetic resonance, and the selectivity was greater than 90%.

Example 12

Pd(OAc) ₂ (0.2 mg, 0.001 mmol), nitrogen phosphine ligand L12 (2.3 mg, 0.004 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), methanol (20 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (62 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave reached 4 MPa. The temperature was quickly raised to 120°C and stirred for 5 hours. After the reaction was completed, the temperature was lowered, and the yield of methyl acrylate was 85% and the selectivity was greater than 90% by nuclear magnetic resonance.

Example 13

Pd(OAc) ₂ (2.2 mg, 0.01 mmol), nitrogen phosphine ligand L13 (7.8 mg, 0.02 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), methanol (20 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (62 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave reached 4 MPa. The temperature was quickly raised to 120°C and stirred for 5 hours. After the reaction was completed, the temperature was lowered, and the yield of methyl acrylate was 80% and the selectivity was greater than 90% by nuclear magnetic resonance.

Embodiment 14

Pd(OAc) ₂ (2.2 mg, 0.01 mmol), nitrogen phosphine ligand L15 (17.4 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), methanol (20 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (62 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave reached 4 MPa. The temperature was quickly raised to 120°C and stirred for 5 hours. After the reaction was completed, the temperature was lowered, and the yield of methyl acrylate was 82% by nuclear magnetic resonance, and the selectivity was greater than 90%.

Embodiment 15

Pd(OAc) ₂ (2.2 mg, 0.01 mmol), nitrogen phosphine ligand L16 (12.0 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), methanol (20 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (62 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave reached 4 MPa. The temperature was quickly raised to 120°C and stirred for 5 hours. After the reaction was completed, the temperature was lowered, and the yield of methyl acrylate was 65% and the selectivity was greater than 90% by nuclear magnetic resonance.

Example 16

Pd(OAc) ₂ (2.2 mg, 0.01 mmol), nitrogen phosphine ligand L17 (15.2 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), methanol (20 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (62 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave was 4 MPa. The temperature was quickly raised to 120°C and stirred for 5 hours. After the reaction was completed, the temperature was lowered, and the yield of methyl acrylate was 61% by nuclear magnetic resonance, and the selectivity was greater than 90%.

Embodiment 17

Pd(OAc) ₂ (2.2 mg, 0.01 mmol), nitrogen phosphine ligand L18 (12.9 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), methanol (20 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (62 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave reached 4 MPa. The temperature was quickly raised to 120°C and stirred for 5 hours. After the reaction was completed, the temperature was lowered, and the yield of methyl acrylate was 76% by nuclear magnetic resonance, and the selectivity was greater than 90%.

Embodiment 18

Pd(CH ₃ CN) ₄ (BF ₄ ) ₂ (4.4 mg, 0.01 mmol), nitrogen phosphine ligand L1 (12.3 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), methanol (10 mL), 1,4-dioxane (10 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (62 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave reached 4 MPa. The temperature was quickly raised to 100°C and stirred for 5 hours. After the reaction was completed, the temperature was lowered, and the yield of methyl acrylate was 80% and the selectivity was greater than 90% by nuclear magnetic resonance.

Embodiment 19

Pd(hfacac) ₂ (3.1 mg, 0.01 mmol), nitrogen phosphine ligand L1 (12.3 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), butanol (5 mL), tetrahydrofuran (15 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (62 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave was 4 MPa. The temperature was quickly raised to 120°C and stirred for 5 hours. After the reaction was completed, the temperature was lowered, and the yield of butyl acrylate was 92% and the selectivity was greater than 93% by nuclear magnetic resonance.

Embodiment 20

Pd(OTFA) ₂ (4.0 mg, 0.01 mmol), nitrogen phosphine ligand L1 (12.3 mg, 0.04 mmol), p-toluenesulfonic acid (17.5 mg, 0.10 mmol), octanol (5 mL), tetrahydrofuran (15 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (100 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave reached 6 MPa. The temperature was quickly raised to 120°C and stirred for 5 hours. After the reaction was completed, the temperature was lowered, and the yield of octyl acrylate was 86% by nuclear magnetic resonance, and the selectivity was greater than 90%.

Embodiment 21

Pd(OPiv) ₂ (0.3 mg, 0.001 mmol), nitrogen phosphine ligand L1 (1.2 mg, 0.004 mmol), methanesulfonic acid (1.0 μL, 1.6 mmol), methanol (20 mL) and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (100 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave reached 6 MPa. The temperature was quickly raised to 80 ° C and stirred for 10 hours. After the reaction was completed, the temperature was lowered, and the yield of methyl acrylate was 89% by nuclear magnetic resonance, and the selectivity was greater than 90%.

Embodiment 22

Pd ₂ (dba) ₃ (4.6 mg, 0.005 mmol), nitrogen phosphine ligand L1 (12.3 mg, 0.04 mmol), trifluoroacetic acid (12 μL, 0.16 mmol), methanol (20 mL), and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (100 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave reached 6 MPa. The temperature was quickly raised to 40°C and stirred for 6 hours. After the reaction was completed, the temperature was lowered, and the yield of methyl acrylate was 85% and the selectivity was greater than 90% by nuclear magnetic resonance.

Embodiment 23

Pd(OAc) ₂ (2.24 mg, 0.01 mmol), nitrogen phosphine ligand L1 (12.3 mg, 0.04 mmol), methanesulfonic acid (10.4 μL, 0.16 mmol), methanol (20 mL), and a stirrer were added to a 300 mL Parr autoclave under nitrogen protection, and acetylene gas was replaced. Acetylene gas (100 mmol) was added through a flow meter under cooling, and then carbon monoxide was added until the pressure in the autoclave was 6 MPa. The reaction was stirred at room temperature for 10 hours. After the reaction, the yield of methyl acrylate was 85% and the selectivity was greater than 90% by nuclear magnetic resonance.

When the phosphine ligand of the present invention is used for catalytic preparation of acrylic ester, the acrylic ester product can be obtained with a relatively high yield (>55%, the best embodiment>80%) and good selectivity, and therefore has potential industrial application.

In addition, the phosphine ligand of the present invention has a good catalytic conversion rate, and thus the catalytic reaction can be completed at a low dosage (<10 ^-4 equivalent, preferably <10 ^-5 equivalent, and more preferably <10 ^-6 equivalent).

All documents mentioned in the present invention are cited as references in this application, just as each document is cited as reference individually. In addition, it should be understood that after reading the above teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims (10)

1. A phosphine ligand, characterized in that the ligand has a structure selected from the group consisting of: in, R ¹ is selected from the following group: substituted or unsubstituted C _1-10 alkyl, substituted or unsubstituted C _3-12 cycloalkyl (adamantyl), substituted or unsubstituted C _6-30 aryl; ^R2 is selected from the group consisting of substituted or unsubstituted 5-20 membered heteroaryl; ^R3 is hydrogen, substituted or unsubstituted _C1-10 alkyl, substituted or unsubstituted _C1-10 alkoxy, substituted or unsubstituted _C2-10 ester, cyano, COOH, benzenesulfonyl, trialkylsilyl (wherein the alkyl is _C1-4 alkyl), nitro, substituted or unsubstituted _C6-30 aryl, substituted or unsubstituted 5-30 membered heteroaryl; or two ^R3 located on adjacent carbon atoms and the carbon atom to which they are connected together constitute a group selected from the group consisting of _C6-10 aryl, 5-12 membered heteroaryl; In the ligand, A is a substituted or unsubstituted C _1-4 alkylene group, or the A and Together in, is the linking site connected to P; Wherein, R ⁴ is one or more substituents located on the corresponding ring selected from the group consisting of H, C _1-10 alkyl, C _1-10 alkoxy, C _2-10 ester, cyano, COOH, benzenesulfonyl, trialkylsilyl (wherein the alkyl is C _1-4 alkyl), nitro, C _6-30 aryl, 5-30 membered heteroaryl; or together with R ³ and one or more ring atoms on the pyridine ring, forms a 5-7 membered carbocyclic or heterocyclic ring; Unless otherwise specified, the substitution refers to that one or more hydrogen atoms on the group are replaced by a substituent selected from the group consisting of C _1-10 alkyl, C _1-10 alkoxy, C _2-10 ester, cyano, COOH, benzenesulfonyl, trialkylsilyl (wherein the alkyl is C _1-4 alkyl), nitro, C _6-30 aryl, and 5-30 membered heteroaryl. 2. The ligand according to claim 1, characterized in that in the ligand, A is CH ₂ or or the A and Together in, is the linking site connected to P; Wherein, R ⁴ is one or more substituents located on the corresponding ring and selected from the following group: H, C _1-10 alkyl, C _1-10 alkoxy, C _2-10 ester, cyano, COOH, benzenesulfonyl, trialkylsilyl (wherein the alkyl is C _1-4 alkyl). 3. The ligand according to claim 1, characterized in that, in the ligand, R ¹ is selected from the group consisting of a substituted or unsubstituted C _1-10 alkyl group, a substituted or unsubstituted C _3-10 cycloalkyl group; ^R2 is selected from the group consisting of substituted or unsubstituted 5-10 membered heteroaryl; R ³ is hydrogen, C _1-10 alkyl, C _1-10 alkoxy, C _2-10 ester, cyano, trialkylsilyl (wherein the alkyl is C _1-4 alkyl), nitro, -CH(Ph) ₂ , C _6-30 aryl, 5-10 membered heteroaryl. 4. The ligand according to claim 1, characterized in that, in the ligand, ^R1 is 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 is selected from the group consisting of pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrrolyl, imidazolyl, pyrazolyl, thienyl, furanyl, thiazolyl, triazolyl; and said R ² may be optionally substituted by one or more substituents selected from the group consisting of C _1-4 alkyl; R ³ is selected from the group consisting of methyl, n-propyl, isopropyl, tert-butyl, methoxy, cyano, COOH, -CH(Ph) ₂ , benzenesulfonyl, and trimethylsilyl. 5. The ligand according to claim 1, characterized in that the ligand is selected from the group consisting of: 6. A method for synthesizing acrylic acid ester by carbonylation of acetylene catalyzed by palladium, characterized in that the method comprises the steps of: a) in a reaction vessel, dissolving a palladium catalyst, a phosphine ligand and an acid in an alcohol and an optional solvent; wherein the phosphine ligand is a phosphine ligand of formula I as claimed in claim 1; b) introducing acetylene into the kettle and then introducing carbon monoxide to react; c) End the reaction and separate the product. 7. The method according to claim 6, characterized in that the alcohol is a C _1-12 alkyl alcohol; preferably, the alcohol is selected from the group consisting of methanol, ethanol, propanol, butanol, octanol, or a combination thereof. 8. The method of claim 6, wherein the palladium catalyst is selected from the group consisting of palladium acetate, palladium trifluoroacetate, palladium pentanoate, palladium tetraacetonitrile tetrafluoroborate, palladium hexafluoroacetylacetonate, palladium di(acetylacetone), palladium tetraacetonitrile trifluoromethanesulfonate, palladium pivalate, bis(dibenzylideneacetone) palladium, tris(dibenzylideneacetone) dipalladium, palladium chloride, diacetonitrile palladium dichloride, dibenzonitrile palladium dichloride, or a combination thereof. 9. The method of claim 6, wherein 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 (wherein the alkyl is a C _1-12 alkyl), and aryl sulfonic acid (wherein the aryl is a C _6-10 aryl). 10. The method according to claim 6, wherein the solvent is selected from the group consisting of alkane solvents, substituted aromatic solvents, ether solvents, ketone solvents, nitrile solvents, ester solvents, or a combination thereof.