Pyrazine phosphine ligand compound as well as preparation method and application thereof

Abstract

The invention provides a pyrazine phosphine ligand compound as well as a preparation method and application thereof, and relates to the technical field of catalysts. According to the preparation method disclosed by the invention, the raw materials are subjected to lithiation reaction and then react with different monochlorophosphine compounds to generate corresponding pyrazine phosphine ligand compounds, and the preparation method is simple, few in separation steps, high in yield and suitable for industrial production. The invention also relates to a catalytic system formed by complexing a series of pyrazine phosphine ligand compounds serving as ligands and a metal center, and the catalytic system is used for catalyzing olefin hydroformylation reaction, hydrocarboxylation reaction and hydrocyanation reaction. Particularly, the catalytic system has good activity and selectivity in a reaction for preparing methyl propionate through an alkoxycarbonylation reaction of ethylene.

Description

Technical Field

[0001] The present invention relates to the field of catalysts, and in particular to a pyrazine phosphine ligand compound, a preparation method and an application thereof, and in particular to a pyrazine phosphine ligand compound, a preparation method thereof and an application thereof in preparing a catalyst for olefin alkoxycarbonylation reaction, olefin hydroformylation reaction, hydrocarboxylation reaction or hydrocyanation reaction. Background Art

[0002] Phosphine ligand compounds are an important catalyst ligand, which are widely used in transition metal catalyst ligands, epoxy resin curing accelerators and other purposes. For example, bisphosphine ligands such as Xphos, Sphos, and Ruphos catalyze the Suzuki coupling reaction in a catalyst system composed of palladium and rhodium. 2,2'-Bis(diphenylphosphinomethyl)-1,1'-biphenyl and its derivatives are catalyst ligands that show good activity and selectivity in hydroformylation reactions. At present, the most mature catalytic system for industrial catalytic olefin carbonylation reaction is the 1,2-bis(di-tert-butylphosphinomethyl)benzene / palladium catalytic system of the Whiston research group. Patents WO 96 / 19434, EPA04489472, and EPA0499329 describe the application of this catalytic system. Compared with the traditional triphenylphosphine-modified palladium catalyst system, it has a bidentate phosphine ligand with rich electrons and greater steric hindrance (recorded in Chem. Commun. 2004, 1720-1721) and exhibits better catalytic performance. Its biggest advantage is that it can efficiently catalyze the alkoxycarbonylation reaction of ethylene under milder reaction conditions. (EPA04489472, EPA0499329, EPA0495547, US2005085671A1, US6284919B1, US2001051745A1, US6476255B1).

[0003] At present, the structures of the organophosphine ligand compounds that have been reported to catalyze the alkoxycarbonylation of olefins and show good activity and selectivity are mostly benzene ring skeletons, and the types of ligands that can efficiently catalyze the alkoxycarbonylation of olefins are scarce. The DTBPX ligand used by Lucaite has been widely studied and patented. If you want to use foreign catalysts and processes, you need to pay high patent fees and process package transfer fees. In addition, the DTBPX ligand has problems such as poor stability, easy hydrolysis, acidolysis, and easy blocking of pipelines, and it is necessary to add ligands from time to time to ensure catalytic activity.

[0004] The present invention provides a novel phosphine ligand compound based on pyrazine, a preparation method and application thereof. Compared with the DTBPX ligand, the novel structural compound based on the novel phosphine ligand and the preparation method developed in the present invention have the characteristics of being easy to synthesize and can be synthesized on a larger scale, having a high yield, having good reaction activity, and not being easy to decompose. At the same time, after preliminary industrial pilot studies and comparisons with DTBPX and other phosphine ligands, the novel phosphine ligand compound based on pyrazine developed in the present invention can achieve a high-activity and high-selectivity reaction of alkoxycarbonylation of olefins, and has great potential and practical value for the development of alkoxycarbonylation reactions of olefins in the future.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] One of the purposes of the present invention is to provide a pyrazine phosphine ligand compound. The ligand can be a monophosphine, diphosphine or polyphosphine compound with a novel structure and can control the ligand electronic effect and steric hindrance.

[0007] The second object of the present invention is to provide a method for preparing a pyrazine phosphine ligand compound. The method has simple preparation process, good environmental protection, few synthesis and separation steps, high production efficiency, and is suitable for industrial production.

[0008] The third object of the present invention is to provide a pyrazine phosphine ligand compound for use in preparing a catalyst for alkoxycarbonylation of olefins, alkene hydroformylation, hydrocarboxylation or hydrocyanation. The compound is used as a ligand to form a catalytic system with a metal center, especially a highly efficient catalyst for alkoxycarbonylation of olefins, showing good activity and product selectivity.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0010] In a first aspect, the present invention provides a pyrazine phosphine ligand compound, wherein the structural formula of the pyrazine phosphine ligand compound includes any one of the following formulas I to IV:

[0011]

[0012] in,

[0013] R 1 and R 2 Each is independently selected from any one of a substituted or unsubstituted alkyl group, a substituted or unsubstituted silyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group;

[0014] R 3 , R 4 and R 5Each is independently selected from any one of hydrogen, substituted or unsubstituted alkyl, halogen or nitro;

[0015] Y is selected from

[0016] Preferably, the R 1 and R 2 Each is independently selected from any one of a substituted or unsubstituted C1-C12 alkyl group, a substituted or unsubstituted C3-C12 silyl group, a substituted or unsubstituted C3-C12 cycloalkyl group, a substituted or unsubstituted C6-C12 aryl group or a substituted or unsubstituted C3-C12 heteroaryl group.

[0017] Preferably, the R 1 and R 2 Each is independently selected from any one of isopropyl, tert-butyl, n-butyl, dimethyl-tert-butylsilyl, triisopropylsilyl, cyclohexyl, adamantyl, phenyl, pyridyl, N-methylpyrrolyl, N-methylimidazolyl, quinolyl, furanyl and thiofuranyl.

[0018] Preferably, the R 3 , R 4 and R 5 Each is independently selected from any one of hydrogen, unsubstituted C1-C4 alkyl, halogen or nitro.

[0019] Preferably, the pyrazine phosphine ligand compound includes any one of the following compounds L1 to L8:

[0020]

[0021] In a second aspect, the present invention provides a method for preparing the pyrazine phosphine ligand compound as described in the first aspect, the preparation method comprising the following steps:

[0022] (1) reacting a pyrazine compound, N,N,N,N-tetramethylethylenediamine, an alkaline salt and n-butyl lithium to obtain a pyrazine metal salt;

[0023] (2) A pyrazine metal salt is reacted with a monochlorophosphine compound to obtain the pyrazine phosphine ligand compound.

[0024] Preferably, in step (1), the structural formula of the pyrazine compound is as shown in Formula A below:

[0025]

[0026] Among them, R 1 '、R 2 '、R 3 and R 4 Each is independently selected from hydrogen or substituted or unsubstituted alkyl.

[0027] Preferably, in step (1), the alkaline salt is selected from sodium tert-butoxide and / or potassium tert-butoxide.

[0028] Preferably, in step (1), the molar ratio of the pyrazine compound, N,N,N,N-tetramethylethylenediamine, alkaline salt and n-butyllithium is 1:(1.5-4):(2-9):(2-9).

[0029] Preferably, in step (1), the reaction is carried out in an alkane solvent.

[0030] Preferably, the alkane solvent is heptane.

[0031] Preferably, in step (1), the reaction is carried out in the presence of a protective gas.

[0032] Preferably, the protective gas comprises nitrogen and / or argon.

[0033] Preferably, in step (1), the reaction temperature is 0 to 5° C., and the reaction time is 12 to 24 hours.

[0034] Preferably, in step (1), the specific steps of the reaction are:

[0035] Under a protective gas atmosphere, a pyrazine compound, N,N,N,N-tetramethylethylenediamine and an alkaline salt are dissolved in an alkane solvent, the temperature is cooled, and then an alkane solution of n-butyllithium is added dropwise to react to obtain a reaction solution.

[0036] Preferably, in step (1), the following post-treatment steps are further included after the reaction is completed.

[0037] The reaction solution is filtered, washed and dried in sequence to obtain the pyrazine metal salt.

[0038] Preferably, the structural formula of the monochlorophosphine compound is as shown in the following formula B:

[0039]

[0040] Among them, R 1 and R 2 Each is independently selected from any one of a substituted or unsubstituted alkyl group, a substituted or unsubstituted silyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group.

[0041] Preferably, in step (2), the molar ratio of the pyrazine metal salt to the monochlorophosphine compound is 1:(2-9), preferably 1:2.

[0042] Preferably, in step (2), the reaction is carried out in an alkane solvent and / or an ether solvent.

[0043] Preferably, the alkane solvent is hexane.

[0044] Preferably, the ether solvent is methyl tert-butyl ether.

[0045] Preferably, in step (2), the reaction temperature is 0 to 30° C., and the reaction time is 12 to 20 hours.

[0046] Preferably, in step (2), the specific steps of the reaction are:

[0047] The pyrazine metal salt is dissolved in an alkane solvent and / or an ether solvent, cooled, and then a monochlorophosphine compound is added dropwise to react to obtain a reaction solution.

[0048] Preferably, the temperature for dropping the monochlorophosphine compound is below 5°C.

[0049] Preferably, in step (2), the following post-treatment steps are further included after the reaction is completed:

[0050] Water is added to the reaction solution to quench the reaction, and then the reaction solution is separated, the organic phase is dried, filtered, and the solvent is removed in vacuo to obtain a crude product; the crude product is slurried and filtered to obtain the pyrazine phosphine ligand compound.

[0051] In a third aspect, the present invention provides a use of the pyrazine phosphine ligand compound as described in the first aspect in the preparation of a catalyst for olefin alkoxycarbonylation, olefin hydroformylation, hydrocarboxylation or hydrocyanation.

[0052] In a fourth aspect, the present invention provides a composite catalyst, the composite catalyst comprising a coordinated metal center and the pyrazine phosphine ligand compound of the first aspect;

[0053] Wherein, the coordination metal center includes any one of iron, cobalt, nickel, ruthenium, rhodium, iridium or palladium, or a combination of at least two thereof.

[0054] Preferably, the raw materials for preparing the composite catalyst include: the pyrazine phosphine ligand compound, a metal precursor and an acidic auxiliary agent.

[0055] Preferably, the metal precursor is selected from any one or a combination of at least two of iron-containing compounds, cobalt-containing compounds, nickel-containing compounds, ruthenium-containing compounds, rhodium compounds, iridium-containing compounds or palladium-containing compounds, preferably cobalt-containing compounds and / or palladium-containing compounds, preferably palladium-containing compounds.

[0056] Preferably, the palladium-containing compound is selected from any one of palladium chloride, palladium acetate, palladium acetylacetonate or palladium dibenzylideneacetone, or a combination of at least two thereof.

[0057] Preferably, the acid auxiliary agent includes any one of methanesulfonic acid, trifluoroacetic acid or p-toluenesulfonic acid or a combination of at least two thereof, preferably p-toluenesulfonic acid.

[0058] Preferably, the molar ratio of the metal precursor, the pyrazine phosphine ligand compound and the acidic auxiliary agent is 1:(1-8):(0.5-1.2).

[0059] Preferably, the raw materials for preparing the composite catalyst also include a solvent.

[0060] Preferably, the solvent is methanol.

[0061] In a fifth aspect, the present invention provides a method for alkoxycarbonylation of an olefin, the method comprising the following steps:

[0062] In the presence of the composite catalyst described in the fourth aspect, olefin, carbon monoxide and / or methanol undergo an alkoxycarbonylation reaction to obtain an alkoxycarbonylation product of olefin. (Methanol can be used as a reaction raw material and / or as a reaction solvent.)

[0063] Preferably, the olefin is selected from any one or a combination of at least two of substituted or unsubstituted C2 to C20 olefins, preferably any one or a combination of at least two of ethylene, propylene, butene or n-hexene, preferably ethylene.

[0064] Preferably, in the alkoxycarbonylation reaction system, the concentration of the pyrazine phosphine ligand compound in the composite catalyst is 500 to 2500 ppm, preferably 700 to 1500 ppm.

[0065] Preferably, the molar ratio of the olefin to carbon monoxide is (1-2):1.

[0066] Preferably, the temperature of the alkoxycarbonylation reaction is 70-110° C., and the pressure of the alkoxycarbonylation reaction is 1.0-2.5 MPa.

[0067]

Term Explanation

[0068] Various aspects and features of the present invention are further described below.

[0069] The various terms and phrases used in the present invention have the general meanings known to those skilled in the art. Even so, the present invention still hopes to provide a more detailed description and explanation of these terms and phrases. If the terms and phrases mentioned are inconsistent with the known meanings, the meanings expressed in the present invention shall prevail. The following are the definitions of various terms used in the present invention, which apply to the terms used in the entire specification of this application, unless otherwise specified in specific circumstances.

[0070] As mentioned in the present invention, the terms "halogen", "halogen", "halogen atom", "halo" and the like represent fluorine, chlorine, bromine or iodine, and specifically represent fluorine, chlorine or bromine.

[0071] As mentioned in the present invention, the term "alkyl" refers to an alkyl group having a specified number of carbon atoms, which can be a straight-chain alkyl group or a branched alkyl group. For example, the "C1-C12 alkyl group" refers to a straight-chain alkyl group or a branched alkyl group having 1 to 12 carbon atoms, and specific groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, n-hexyl, n-heptyl, n-octyl, etc., and similar groups.

[0072] As mentioned in the present invention, the term "silyl group" covers the above-mentioned alkyl-substituted silicon groups, for example, the "C3-C12 silyl group" refers to an alkyl-substituted silicon group having 3 to 12 carbon atoms, and specific groups include trimethylsilyl, triethylsilyl, methyldiethylsilyl, ethyldimethylsilyl, tripropylsilyl, tributylsilyl, triisopropylsilyl, methyldiisopropylsilyl, dimethyl-tert-butylsilyl, and the like, and similar groups.

[0073] As mentioned in the present invention, the term "cycloalkyl" refers to a cyclic alkyl group having a specified number of ring carbon atoms. For example, when "C3-C12 cycloalkyl" is mentioned, it refers to a cycloalkyl group having 3 to 12 carbon atoms, and specific groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, adamantyl, etc., and similar groups.

[0074] As used herein, the term "aryl" refers to monocyclic or polycyclic (eg, having 2, 3, or 4 fused rings) aromatic hydrocarbons, such as phenyl, naphthyl, anthracenyl, phenanthrenyl, indenyl, and the like.

[0075] As used herein, the term "heteroaryl" refers to an aromatic heterocycle having at least one heteroatom ring member such as O, N or S. Heteroaryl groups include monocyclic or polycyclic (e.g., having 2, 3 or 4 fused rings) ring systems. Any annular N atom in a heterocyclic group may also be oxidized to form an N-oxide. Examples of preferred "heteroaryl" groups include, but are not limited to, pyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, triazinyl, furanyl, thiofuranyl, thienyl, imidazolyl, N-methylimidazolyl, triazolyl, tetrazolyl, thiazolyl, isothiazolyl, 1,2,4-thiadiazolyl, pyrrolyl, N-methylpyrrolyl, pyrazolyl, oxazolyl, isoxazolyl, oxadiazolyl, benzofuranyl, benzothiophenyl, benzothiazolyl, indolyl, indazolyl, quinolyl, isoquinolyl, purinyl, carbazolyl, benzimidazolyl, pyrrolopyridinyl, pyrrolopyrimidinyl, pyrazolopyridinyl, pyrazolopyrimidinyl, the like, and the like.

[0076] As mentioned in the present invention, the term "compound", as used herein, is meant to include all stereoisomers, geometric isomers, tautomers, isotopes.

[0077] Compared with the prior art, the present invention has the following beneficial effects:

[0078] (1) The phosphine ligand compound of the present invention uses substituted pyrazine as the initial raw material, and can obtain pyrazine-type monophosphine, diphosphine or polyphosphine compounds through lithiation reaction and double decomposition reaction. The compounds have novel structures and can control the ligand electronic effect and steric hindrance.

[0079] (2) The method for preparing the pyrazine-type phosphine ligand compound of the present invention has a simple synthesis route, high economic efficiency, few separation steps, good environmental protection, and is suitable for industrial production.

[0080] (3) The use of the pyrazine-type phosphine ligand compound described in the present invention in the catalytic reaction of olefins. The compound acts as a ligand to complex with a metal center to form a catalytic system, and catalyzes the hydroformylation reaction, alkoxycarbonylation reaction, and hydrocyanation reaction of olefins. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0082] Figure 1 This is a diagram of the ethylene alkoxycarbonylation continuous reaction device provided by the present invention. DETAILED DESCRIPTION

[0083] Unless otherwise defined herein, scientific and technological terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear, however, in the case of any potential ambiguity, the definitions provided herein take precedence over any dictionary or external definitions. In this application, unless otherwise stated, the use of "or" means "and / or". In addition, the use of the term "including" and other forms is non-limiting.

[0084] It should be noted that specific details are described in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in a variety of other ways different from those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0085] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0086] In a first aspect, the present invention provides a pyrazine phosphine ligand compound, wherein the structural formula of the pyrazine phosphine ligand compound includes any one of the following formulas I to IV:

[0087]

[0088] in,

[0089] R 1 and R 2 Each is independently selected from any one of a substituted or unsubstituted alkyl group, a substituted or unsubstituted silyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group;

[0090] R 3 , R 4 and R 5 Each is independently selected from any one of hydrogen, substituted or unsubstituted alkyl, halogen or nitro;

[0091] Y is selected from

[0092] As an optional embodiment, the R 1 and R 2Each is independently selected from any one of a substituted or unsubstituted C1-C12 alkyl group, a substituted or unsubstituted C3-C12 silyl group, a substituted or unsubstituted C3-C12 cycloalkyl group, a substituted or unsubstituted C6-C12 aryl group or a substituted or unsubstituted C3-C12 heteroaryl group.

[0093] As an optional embodiment, the R 1 and R 2 Each is independently selected from any one of isopropyl, tert-butyl, n-butyl, dimethyl-tert-butylsilyl, triisopropylsilyl, cyclohexyl, adamantyl, phenyl, pyridyl, N-methylpyrrolyl, N-methylimidazolyl, quinolyl, furanyl and thiofuranyl.

[0094] As an optional embodiment, the R 3 , R 4 and R 5 Each is independently selected from any one of hydrogen, unsubstituted C1-C4 alkyl, halogen or nitro.

[0095] As an optional embodiment, the pyrazine phosphine ligand compound includes any one of the following compounds L1 to L8:

[0096]

[0097] In a second aspect, the present invention provides a method for preparing the pyrazine phosphine ligand compound as described in the first aspect, the preparation method comprising the following steps:

[0098] (1) reacting a pyrazine compound, N,N,N,N-tetramethylethylenediamine, an alkaline salt and n-butyl lithium to obtain a pyrazine metal salt;

[0099] (2) A pyrazine metal salt is reacted with a monochlorophosphine compound to obtain the pyrazine phosphine ligand compound.

[0100] As an optional embodiment, in step (1), the structural formula of the pyrazine compound is shown in Formula A below:

[0101]

[0102] Among them, R 1 '、R 2 '、R 3 and R 4 Each is independently selected from hydrogen or substituted or unsubstituted alkyl.

[0103] As an optional embodiment, in step (1), the alkaline salt is selected from sodium tert-butoxide and / or potassium tert-butoxide.

[0104] As an optional embodiment, in step (1), the molar ratio of the pyrazine compound, N,N,N,N-tetramethylethylenediamine, alkaline salt and n-butyllithium is 1:(1.5-4):(2-9):(2-9);

[0105] Here, “1.5-4” may be, for example, 1.5, 2, 2.5, 3, 3.5, 4, etc.;

[0106] The first "2-9" may be, for example, 2, 3, 4, 5, 6, 7, 8, 9, etc.;

[0107] Among them, the second "2-9" can be, for example, 2, 3, 4, 5, 6, 7, 8, 9, etc.

[0108] As an optional embodiment, in step (1), the reaction is carried out in an alkane solvent.

[0109] As an optional embodiment, in step (1), the alkane solvent is heptane.

[0110] As an optional embodiment, in step (1), the reaction is carried out in the presence of a protective gas.

[0111] As an optional embodiment, in step (1), the protective gas includes nitrogen and / or argon.

[0112] As an optional embodiment, in step (1), the reaction temperature is 0-5°C, for example, 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, etc., and the reaction time is 12-24h, for example, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h, 30h, etc.

[0113] As an optional embodiment, in step (1), the specific steps of the reaction are:

[0114] Under a protective gas atmosphere, a pyrazine compound, N,N,N,N-tetramethylethylenediamine and an alkaline salt are dissolved in an alkane solvent, the temperature is cooled, and then an alkane solution of n-butyllithium is added dropwise to react to obtain a reaction solution.

[0115] As an optional embodiment, in step (1), the following post-treatment steps are further included after the reaction is completed.

[0116] The reaction solution is filtered, washed and dried in sequence to obtain the pyrazine metal salt.

[0117] As an optional embodiment, the structural formula of the monochlorophosphine compound is shown in the following formula B:

[0118]

[0119] Among them, R 1 and R 2 Each is independently selected from any one of a substituted or unsubstituted alkyl group, a substituted or unsubstituted silyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group.

[0120] As an optional embodiment, in step (2), the molar ratio of the pyrazine metal salt to the monochlorophosphine compound is 1:(2-9), for example, it can be 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, etc., preferably 1:2.

[0121] As an optional embodiment, in step (2), the reaction is carried out in an alkane solvent and / or an ether solvent.

[0122] As an optional embodiment, in step (2), the alkane solvent is hexane.

[0123] As an optional embodiment, in step (2), the ether solvent is methyl tert-butyl ether.

[0124] As an optional embodiment, in step (2), the reaction temperature is 0-30°C, for example, it can be 0°C, 2°C, 4°C, 6°C, 8°C, 10°C, 12°C, 14°C, 16°C, 18°C, 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, etc., and the reaction time is 12-20h, for example, it can be 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, etc.

[0125] As an optional embodiment, in step (2), the specific steps of the reaction are:

[0126] The pyrazine metal salt is dissolved in an alkane solvent and / or an ether solvent, cooled, and then a monochlorophosphine compound is added dropwise to react to obtain a reaction solution.

[0127] As an optional embodiment, the temperature for adding the monochlorophosphine compound is below 5°C, for example, it can be 5°C, 4°C, 3°C, 2°C, 1°C, 0°C, -1°C, -2°C, -3°C, -4°C, -5°C, etc.

[0128] As an optional embodiment, in step (2), after the reaction is completed, the following post-treatment steps are also included:

[0129] Water is added to the reaction solution to quench the reaction, and then the reaction solution is separated, the organic phase is dried, filtered, and the solvent is removed in vacuo to obtain a crude product; the crude product is slurried and filtered to obtain the pyrazine phosphine ligand compound.

[0130] In a third aspect, the present invention provides a use of the pyrazine phosphine ligand compound as described in the first aspect in the preparation of a catalyst for olefin alkoxycarbonylation, olefin hydroformylation, hydrocarboxylation or hydrocyanation.

[0131] In a fourth aspect, the present invention provides a composite catalyst, the composite catalyst comprising a coordinated metal center and the pyrazine phosphine ligand compound of the first aspect;

[0132] Wherein, the coordination metal center includes any one of iron, cobalt, nickel, ruthenium, rhodium, iridium or palladium, or a combination of at least two thereof.

[0133] As an optional implementation, the raw materials for preparing the composite catalyst include: the pyrazine phosphine ligand compound, a metal precursor and an acidic auxiliary agent.

[0134] As an optional embodiment, the metal precursor is selected from any one or a combination of at least two of iron-containing compounds, cobalt-containing compounds, nickel-containing compounds, ruthenium-containing compounds, rhodium compounds, iridium-containing compounds or palladium-containing compounds, preferably a cobalt-containing compound and / or a palladium-containing compound, preferably a palladium-containing compound.

[0135] As an optional embodiment, the palladium-containing compound is selected from any one of palladium chloride, palladium acetate, palladium acetylacetonate or dibenzylideneacetone palladium, or a combination of at least two thereof.

[0136] As an optional embodiment, the acid auxiliary agent includes any one of methanesulfonic acid, trifluoroacetic acid or p-toluenesulfonic acid or a combination of at least two thereof, preferably p-toluenesulfonic acid.

[0137] As an optional embodiment, the molar ratio of the metal precursor, the pyrazine phosphine ligand compound and the acidic auxiliary agent is 1:(1-8):(0.5-1.2);

[0138] Among them, "1-8" can be, for example, 1, 2, 3, 4, 5, 6, 7, 8, etc.;

[0139] Here, “0.5-1.2” can be, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, etc.

[0140] As an optional implementation, the raw materials for preparing the composite catalyst also include a solvent.

[0141] As an optional embodiment, the solvent is methanol.

[0142] In a fifth aspect, the present invention provides a method for alkoxycarbonylation of an olefin, the method comprising the following steps:

[0143] In the presence of the composite catalyst described in the fourth aspect, olefin, carbon monoxide and / or methanol undergo an alkoxycarbonylation reaction to obtain an alkoxycarbonylation product of olefin. (Wherein, methanol is a ligand solvent and / or a reaction raw material.)

[0144] As an optional embodiment, the present invention provides an application based on a new pyrazine phosphine ligand compound, wherein a metal precursor and a new pyrazine phosphine ligand compound are dissolved in a solvent in proportion to prepare a metal / pyrazine phosphine ligand catalytic system; the prepared catalytic system reacts with a certain proportion of olefins, carbon monoxide, and methanol at a certain temperature and pressure with high activity and high selectivity.

[0145] As an optional embodiment, the olefin is selected from any one or a combination of at least two of substituted or unsubstituted C2 to C20 olefins, preferably any one or a combination of at least two of ethylene, propylene, butene or n-hexene, preferably ethylene.

[0146] As an optional embodiment, in the alkoxycarbonylation reaction system, the concentration of the pyrazine phosphine ligand compound in the composite catalyst is 500-2500 ppm, for example, it can be 500 ppm, 600 ppm, 800 ppm, 1000 ppm, 1200 ppm, 1400 ppm, 1500 ppm, 1600 ppm, 1800 ppm, 2000 ppm, 2200 ppm, 2400 ppm, 2500 ppm, etc., preferably 700-1500 ppm.

[0147] As an optional embodiment, the temperature of the alkoxycarbonylation reaction is 70-110°C, for example, it can be 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, etc., and the pressure of the alkoxycarbonylation reaction is 1.0-2.5Mpa, for example, it can be 1.0Mpa, 1.2Mpa, 1.4Mpa, 1.6Mpa, 1.8Mpa, 2Mpa, 2.2Mpa, 2.4Mpa, 2.5Mpa, etc.

[0148] In the present invention, the alkene alkoxycarbonylation method can be carried out intermittently or in a continuous manner. In the industrial method of the continuous method, the metal catalyst and pyrazine phosphine ligand and acidic auxiliary agent and reaction solvent etc. prepared in advance are added into the reactor to start the continuous synthesis method, and after being heated to the required reaction temperature, olefins, carbon monoxide and methanol are introduced into the above-mentioned reaction mixture in a continuous or intermittent manner. The effluent of the reactor contains carbonylation product, metal / pyrazine phosphine ligand, acidic auxiliary agent, unreacted olefins, carbon monoxide and reaction solvent etc., which can be derived from the reactor into the evaporator / separator. By reducing pressure, the gaseous reactant carbon monoxide and olefins are separated from the mixture, and the carbonylation product can be collected by the mode of molecular distillation. The remaining metal / pyrazine phosphine ligand catalyst and all by-products not separated etc. are circulated back into the reactor and reused in the method of the present invention.

[0149] In the present invention, the concentration of the novel pyrazine phosphine ligand needs to be monitored regularly or continuously for the continuously running reaction system. If the concentration is found to be lower than the value, the compound may be lost due to degradation or the like. In this case, the novel pyrazine phosphine ligand compound is added to the mixture of the reaction system.

[0150] In the present invention, the pyrazine phosphine ligand compound is also suitable for hydroformylation reaction, hydrocarboxylation reaction and hydrocyanation reaction.

[0151] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0152] Example 1

[0153] This embodiment provides a pyrazine phosphine ligand compound, and the pyrazine phosphine ligand compound is the following pyrazine phosphine ligand compound L1:

[0154]

[0155] The synthesis route of the pyrazine phosphine ligand compound L1 is as follows:

[0156]

[0157] The preparation method of the pyrazine phosphine ligand compound L1 is as follows:

[0158] (1) Under nitrogen or argon atmosphere, 2-dimethylpyrazine (9.4 g, 0.1 mol), N,N,N,N-tetramethylethylenediamine (23.2 g, 0.2 mol), sodium tert-butoxide (19.2 g, 0.4 mol), and heptane (200 mL) were added into a reactor and stirred, and the mixture was cooled to 5° C., and a hexane solution of n-butyllithium (68 mL, 1.6 M, 0.11 mol) was added dropwise. The mixture was reacted for 12 h, and the pyrazine metal salt was obtained after filtration, washing, and drying.

[0159] (2) Pyrazine metal salt was added to the reactor, hexane (200 mL) was added, the temperature was cooled to 5°C, di-tert-butylphosphine chloride (19.8 g, 0.11 mol) was added dropwise, and the temperature was restored to room temperature for 24 hours after the addition was completed. A white substance was generated, and degassed water was added to quench the reaction. The phases were separated, the hexane phase was dried, filtered, and the solvent was removed in vacuo to obtain a crude product. The crude product was slurried with cold methanol and filtered to obtain the product with a yield of (19.1 g, 80%).

[0160] The H NMR spectrum data of the obtained product are as follows:

[0161] 1 HNMR (C 6 D 6 ,400MHz,298K)δ,ppm:8.51(s,2H,CH on pyrazine),8.45(s,H,CH onpyrazine),3.02(s,6H,C 6 H 6 ,),1.06(s,18H,C(CH 3 ) 3 ).

[0162] Example 2

[0163] This embodiment provides a pyrazine phosphine ligand compound, and the pyrazine phosphine ligand compound is the following pyrazine phosphine ligand compound L2:

[0164]

[0165] The synthesis route of the pyrazine phosphine ligand compound L2 is as follows:

[0166]

[0167] The preparation method of the pyrazine phosphine ligand compound L2 is as follows:

[0168] (1) Under nitrogen or argon atmosphere, 2-dimethylpyrazine (9.4 g, 0.1 mol), N,N,N,N-tetramethylethylenediamine (23.2 g, 0.2 mol), sodium tert-butoxide (19.2 g, 0.4 mol), and heptane (200 mL) were added into a reactor and stirred, and the mixture was cooled to 5° C., and a hexane solution of n-butyllithium (68 mL, 1.6 M, 0.11 mol) was added dropwise. The mixture was reacted for 12 h, and the pyrazine metal salt was obtained after filtration, washing, and drying.

[0169] (2) Pyrazine metal salt was added to the reactor, hexane (200 mL) was added, the temperature was cooled to 5°C, diphenylphosphine chloride (26.5 g, 0.12 mol) was added dropwise, and the temperature was restored to room temperature for 24 hours after the addition was completed. A white substance was generated, and degassed water was added to quench the reaction. The phases were separated, the hexane phase was dried, filtered, and the solvent was removed in vacuo to obtain a crude product. The crude product was slurried with cold methanol and filtered to obtain the product with a yield of (18 g, 78%).

[0170] The H NMR spectrum data of the obtained product are as follows:

[0171] 1 HNMR (C 6 D 6 ,400MHz,298K)δ,ppm:8.52(s,2H,CH on pyrazine),8.47(s,H,CH onpyrazine),7.45(s,6H,C 6 H 6 ,)7.08(s,4H,C 6 H 6 ), 3.02(s, 2H, CH 2 ).

[0172] Example 3

[0173] This embodiment provides a pyrazine phosphine ligand compound, and the pyrazine phosphine ligand compound is the following pyrazine phosphine ligand compound L3:

[0174]

[0175] The synthesis route of the pyrazine phosphine ligand compound L3 is as follows:

[0176]

[0177] The preparation method of the pyrazine phosphine ligand compound L3 is as follows:

[0178] (1) Under nitrogen or argon atmosphere, 2,3-dimethylpyrazine (10.8 g, 0.1 mol), N,N,N,N-tetramethylethylenediamine (34.8 g, 0.3 mol), sodium tert-butoxide (28.8 g, 0.6 mol), and heptane (200 mL) were added into a reactor and stirred, and the mixture was cooled to 5° C., and a hexane solution of n-butyl lithium (136 mL, 1.6 M, 0.2 mol) was added dropwise, and the mixture was reacted for 12 h. The pyrazine metal salt was obtained by filtering, washing, and drying.

[0179] (2) Pyrazine metal salt was added to the reactor, hexane (300 mL) was added, the temperature was cooled to 5°C, diphenylphosphine chloride (52.8 g, 0.22 mol) was added dropwise, and after the addition was completed, the temperature was restored to room temperature and the reaction was continued for 24 hours. A white substance was generated, and degassed water was added to quench the reaction. The phases were separated, the hexane phase was dried, filtered, and the solvent was removed in vacuo to obtain a crude product. The crude product was slurried with cold methanol and filtered to obtain the product with a yield of (36.2 g, 76%).

[0180] The H NMR spectrum data of the obtained product are as follows:

[0181] 1 HNMR (C 6 D 6 ,400MHz,298K)δ,ppm:8.50(s,H,CH on pyrazine),8.45(s,H,CH onpyrazine),7.43(s,12H,C 6 H 6 ,)7.06(s,8H,C 6 H 6 ), 3.01(s, 4H, CH 2 ).

[0182] Example 4

[0183] This embodiment provides a pyrazine phosphine ligand compound, and the pyrazine phosphine ligand compound is the following pyrazine phosphine ligand compound L4:

[0184]

[0185] The synthesis route of the pyrazine phosphine ligand compound L4 is as follows:

[0186]

[0187] The preparation method of the pyrazine phosphine ligand compound L4 is as follows:

[0188] (1) Under nitrogen or argon atmosphere, 2,3-dimethylpyrazine (10.8 g, 0.1 mol), N,N,N,N-tetramethylethylenediamine (34.8 g, 0.3 mol), sodium tert-butoxide (28.8 g, 0.6 mol), and heptane (300 mL) were added into a reactor and stirred, and the mixture was cooled to 5° C., and a hexane solution of n-butyl lithium (136 mL, 1.6 M, 0.2 mol) was added dropwise, and the mixture was reacted for 12 h. After filtering, washing, and drying, a pyrazine metal salt was obtained.

[0189] (2) Pyrazine metal salt was added to the reactor, hexane (350 mL) was added, the temperature was cooled to 5°C, tert-butyl chloro(cyclohexyl)phosphine (45.3 g, 0.22 mol) was added dropwise, and the temperature was restored to room temperature for 24 hours after the addition was completed. A white substance was generated, and degassed water was added to quench the reaction. The phases were separated, the hexane phase was dried, filtered, and the solvent was removed in vacuo to obtain a crude product. The crude product was slurried with cold methanol and filtered to obtain the product with a yield of (32.7 g, 73%).

[0190] The H NMR spectrum data of the obtained product are as follows:

[0191] 1 HNMR (C 6 D 6 ,400MHz,298K)δ,ppm:8.40(s,2H,CH on pyrazine),3.01(s,4H,CH 2 ), 1.61-1.30(m, 20H, CH on cyclohexane), 1.05(s, 18H, C(CH 3 ) 3 ).

[0192] Example 5

[0193] This embodiment provides a pyrazine phosphine ligand compound, and the pyrazine phosphine ligand compound is the following pyrazine phosphine ligand compound L5:

[0194]

[0195] The synthesis route of the pyrazine phosphine ligand compound L5 is as follows:

[0196]

[0197] The preparation method of the pyrazine phosphine ligand compound L5 is as follows:

[0198] (1) Under nitrogen or argon atmosphere, 2,3,5-trimethylpyrazine (12.2 g, 0.1 mol), N,N,N,N-tetramethylethylenediamine (52.2 g, 0.45 mol), sodium tert-butoxide (43.2 g, 0.9 mol), and heptane (400 mL) were added into a reactor and stirred, and the mixture was cooled to 5° C., and a hexane solution of n-butyl lithium (211 mL, 1.6 M, 0.31 mol) was added dropwise, and the mixture was reacted for 12 h. The pyrazine metal salt was obtained after filtering, washing, and drying.

[0199] (2) Pyrazine metal salt was added to the reactor, hexane (450 mL) was added, the temperature was cooled to 5°C, di-tert-butylphosphine chloride (61.2 g, 0.34 mol) was added dropwise, and the temperature was restored to room temperature for 24 hours after the addition was completed. A white substance was generated, and degassed water was added to quench the reaction. The phases were separated, the hexane phase was dried, filtered, and the solvent was removed in vacuo to obtain a crude product. The crude product was slurried with cold methanol and filtered to obtain the product with a yield of (42.5 g, 78%).

[0200] The H NMR spectrum data of the obtained product are as follows:

[0201] 1 HNMR (C 6 D 6 ,400MHz,298K)δ,ppm:8.39(s,H,CH on pyrazine),3.01(s,6H,CH 2 ), 1.03(s, 18H, C(CH 3 ) 3 ).

[0202] Example 6

[0203] This embodiment provides a pyrazine phosphine ligand compound, and the pyrazine phosphine ligand compound is the following pyrazine phosphine ligand compound L6:

[0204]

[0205] The synthesis route of the pyrazine phosphine ligand compound L6 is as follows:

[0206]

[0207] The preparation method of the pyrazine phosphine ligand compound L6 is as follows:

[0208] (1) Under nitrogen or argon atmosphere, 2,3,5,6-tetramethylpyrazine (13.6 g, 0.1 mol), N,N,N,N-tetramethylethylenediamine (69.6 g, 0.6 mol), sodium tert-butoxide (57.6 g, 0.9 mol), and heptane (500 mL) were added into a reactor and stirred, and the mixture was cooled to 5° C., and a hexane solution of n-butyllithium (272 mL, 1.6 M, 0.41 mol) was added dropwise, and the mixture was reacted for 12 h. After filtering, washing, and drying, a pyrazine metal salt was obtained.

[0209] (2) Add pyrazine metal salt to the reactor, add hexane (600 mL), cool to 5°C, add tert-butyl (phenyl) phosphine chloride (88 g, 0.44 mol) dropwise, return to room temperature and react for 24 hours after the addition is completed. A white substance is generated, and degassed water is added to quench the reaction. The phases are separated, the hexane phase is dried, filtered, and the solvent is removed in vacuo to obtain a crude product. The crude product is slurried with cold methanol and filtered to obtain the product with a yield of (58.6 g, 76%).

[0210] The H NMR spectrum data of the obtained product are as follows:

[0211] 1 HNMR (C 6 D 6 ,400MHz,298K)δ,ppm:7.46-7.40(m,8H,C 6 H 6 ), 7.33-7.30 (m, 12H, C 6 H 6 ), 3.02(s,8H,CH 2 ), 1.02(s, 36H, C(CH 3 ) 3 ).

[0212] Example 7

[0213] This embodiment provides a pyrazine phosphine ligand compound, and the pyrazine phosphine ligand compound is the following pyrazine phosphine ligand compound L7:

[0214]

[0215] The synthesis route of the pyrazine phosphine ligand compound L7 is as follows:

[0216]

[0217] The preparation method of the pyrazine phosphine ligand compound L7 is as follows:

[0218] (1) Under nitrogen or argon atmosphere, 2,3,5,6-tetramethylpyrazine (13.6 g, 0.1 mol), N,N,N,N-tetramethylethylenediamine (69.6 g, 0.6 mol), sodium tert-butoxide (57.6 g, 0.9 mol), and heptane (500 mL) were added into a reactor and stirred, and the mixture was cooled to 5° C., and a hexane solution of n-butyllithium (272 mL, 1.6 M, 0.41 mol) was added dropwise, and the mixture was reacted for 12 h. After filtering, washing, and drying, a pyrazine metal salt was obtained.

[0219] (2) Pyrazine metal salt was added to the reactor, hexane (550 mL) was added, the temperature was cooled to 5°C, tert-butyl chloro(cyclohexyl)phosphine (88.58 g, 0.43 mol) was added dropwise, and the temperature was restored to room temperature for 24 hours after the addition was completed. A white substance was generated, and degassed water was added to quench the reaction. The phases were separated, the hexane phase was dried, filtered, and the solvent was removed in vacuo to obtain a crude product. The crude product was slurried with cold methanol and filtered to obtain the product with a yield of (58.8 g, 72%).

[0220] The H NMR spectrum data of the obtained product are as follows:

[0221] 1 HNMR (C 6 D 6 ,400MHz,298K)δ,ppm:3.02(s,8H,CH 2 ),1.62-1.36(m,20H,CH oncyclohexane)1.02(s,36H,C(CH 3 ) 3 ).

[0222] Example 8

[0223] This embodiment provides a pyrazine phosphine ligand compound, and the pyrazine phosphine ligand compound is the following pyrazine phosphine ligand compound L8:

[0224]

[0225] The synthesis route of the pyrazine phosphine ligand compound L8 is as follows:

[0226]

[0227] The preparation method of the pyrazine phosphine ligand compound L8 is as follows:

[0228] (1) Under nitrogen or argon atmosphere, 2,3,5,6-tetramethylpyrazine (13.6 g, 0.1 mol), NN,N,N-tetramethylethylenediamine (69.6 g, 0.6 mol), sodium tert-butoxide (57.6 g, 0.9 mol), and heptane (500 mL) were added into a reactor and stirred, cooled to 5°C, and a hexane solution of n-butyl lithium (272 mL, 1.6 M, 0.41 mol) was added dropwise. The mixture was reacted for 12 h, filtered, washed, and dried to obtain a pyrazine metal salt.

[0229] (2) Pyrazine metal salt was added to the reactor, hexane (600 mL) was added, the temperature was cooled to 5°C, di-tert-butylphosphine chloride (81.1 g, 0.45 mol) was added dropwise, and the temperature was restored to room temperature for 24 hours after the addition was completed. A white substance was generated, and degassed water was added to quench the reaction. The phases were separated, the hexane phase was dried, filtered, and the solvent was removed in vacuo to obtain a crude product. The crude product was slurried with cold methanol and filtered to obtain the product with a yield of (55.5 g, 78%).

[0230] The H NMR spectrum data of the obtained product are as follows:

[0231] 1 HNMR (C 6 D 6 ,400MHz,298K)δ,ppm:3.02(s,8H,CH),,1.03(s,36H,C(CH) 3 ) 3 ), 1.01(s,36H,C(CH 3 ) 3 ).

[0232] Comparative Example 1

[0233] This embodiment provides a phosphine ligand compound, wherein the phosphine ligand compound has the following structure:

[0234]

[0235] Comparative Example 2

[0236] This embodiment provides a phosphine ligand compound, and the phosphine ligand compound has the following structure:

[0237]

[0238] Test Example 1

[0239] Test sample: pyrazine phosphine ligand compound provided in Examples 1 to 8;

[0240] Test method:

[0241] (1) Pd(OAc)2 (29 mg, 0.16 mol%) and one of the novel phosphine ligand compounds L1-L8 (0.38 mmol) specified in Table 1, as well as 70 mL of anhydrous methanol and p-toluenesulfonic acid (0.227 g, 1.5 mol%) were added to a 500 mL stainless steel autoclave equipped with a pressure gauge under a nitrogen atmosphere, and the gas in the autoclave was replaced with nitrogen three times;

[0242] (2) A mixed gas of ethylene and CO (molar ratio of 1:1) was introduced to a total pressure of 2.5 MPa. The mixture was heated to the desired temperature (80°C) under magnetic stirring. Gas was added several times during the reaction to maintain the total pressure at 2.5 MPa. After the reaction lasted for a specified time, the reactor was cooled, the residual gas was vented in a fume hood, the reactor was opened, weighed, and samples were taken for analysis of the product by gas chromatography (GC);

[0243] The test results are shown in Table 1 below:

[0244] Table 1

[0245]

[0246]

[0247] As shown in Table 1, the pyrazine phosphine ligand compounds provided in Examples 1 to 8 are used as catalysts to catalyze the alkoxycarbonylation reaction of olefins, and the ethylene conversion rate reaches more than 95% and the selectivity reaches more than 99%.

[0248] Test Example 2

[0249] Test sample: pyrazine phosphine ligand compound L3 provided in Example 3;

[0250] Test method:

[0251] (1) In a 500 mL stainless steel autoclave equipped with a pressure gauge, a metal palladium source (0.13 mmol) and a designated pyrazine novel phosphine ligand compound L3 (0.38 mmol), as well as 70 mL of anhydrous methanol (70 g) and p-toluenesulfonic acid (1.5 mol%) were added under a nitrogen atmosphere;

[0252] (2) Replace the gas in the autoclave with nitrogen three times, and introduce a mixture of ethylene and CO (1:1) until the total pressure reaches 2.5 MPa. Heat to the desired temperature (80°C) under magnetic stirring. When the pressure in the autoclave drops to 0.2 MPa during the reaction, add gas and pressurize to 2.5 MPa. Repeat this process several times. After the reaction is completed for the specified time, cool the reactor, vent the residual gas in a fume hood, open the autoclave, weigh it, and take a sample to analyze the product by gas chromatography (GC);

[0253] The test results are shown in Table 2 below:

[0254] Table 2

[0255]

[0256]

[0257] As shown in Table 2, in the composite catalyst of the present invention, the metal precursor is preferably a palladium-containing compound, the initiation temperature of which is below 83°C, and the activity and stability of the system are more than 3 times; among them, palladium chloride is the most preferred option, the initiation temperature of which can be reduced to below 70°C, and the activity and stability of the system are as high as more than 10 times.

[0258] Application Example 1

[0259] This application example provides an ethylene alkoxycarbonylation reaction device and an ethylene alkoxycarbonylation reaction method:

[0260] like Figure 1 As shown, a continuous ethylene alkoxycarbonylation reaction device. The feed tower, reactor, separator and evaporator are replaced with nitrogen. Pd(OAc) 2 and the new phosphine ligand L3 of pyrazine are dissolved in 10L of methanol, so that the concentration of Pd(II) is 100mg / L and the molar ratio of Pd / L3 is 1:4. The 10L solution is pumped into a reactor with a volume of 15L through a pipeline; and the separator and evaporator are kept with 2L of solution respectively. Ethylene, carbon monoxide and methanol are respectively 120NL / h 110NL / h reactor and 200g / h, the temperature in the reactor is 80±1℃, and the total gas pressure of ethylene and carbon monoxide is 2.5±0.1MPa. Ethylene, carbon monoxide and methanol react to form methyl propionate under the catalysis of Pd / L3, and the mixed solution containing the reaction product and the catalyst flows from the reactor into the separator, the pressure is reduced to 0.6MPa, and the solution and a small amount of unreacted tail gas are discharged. The solution after gas-liquid separation enters the evaporator for evaporation, part of the product is evaporated, and the remaining product and the catalytic system are returned to the reactor to continue to participate in the reaction.

[0261] In the feed tower, the new pyrazine phosphine ligand compound L3 is dissolved in methanol, and the ligand concentration in the reactor is detected at regular intervals. When the ligand concentration is lower than 800 ppm, the feed tower is opened to pump the new pyrazine phosphine ligand into the reactor, and the concentration of the new pyrazine phosphine ligand is maintained at 800-1600 ppm. The liquid level at the bottom of the reactor, separator and evaporator is kept constant.

[0262] The concentration of the novel pyrazine phosphine ligand L3 in the reactor was monitored by liquid chromatography, and the percentage of methyl propionate was determined by gas chromatography (GC). The reaction was continued for 1000 hours, and the molar ratio of methyl propionate / methanol received at the top of the evaporator remained constant after 150 hours of the reaction, and was always maintained at about 65%.

[0263] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pyrazine phosphine ligand compound, characterized in that: The structural formula of the pyrazine phosphine ligand compound includes any one of the following formulas I to IV: in, R1 and R2 are each independently selected from any one of a substituted or unsubstituted alkyl group, a substituted or unsubstituted silyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group; R3, R4 and R5 are each independently selected from any one of hydrogen, substituted or unsubstituted alkyl, halogen or nitro; Y is selected from 2. The pyrazine phosphine ligand compound according to claim 1, characterized in that: A pyrazine phosphine ligand compound, characterized in that R1 and R2 are each independently selected from any one of a substituted or unsubstituted C1-C12 alkyl group, a substituted or unsubstituted C3-C12 silyl group, a substituted or unsubstituted C3-C12 cycloalkyl group, a substituted or unsubstituted C6-C12 aryl group, or a substituted or unsubstituted C3-C12 heteroaryl group; Preferably, R1 and R2 are each independently selected from any one of isopropyl, tert-butyl, n-butyl, dimethyl-tert-butylsilyl, triisopropylsilyl, cyclohexyl, adamantyl, phenyl, pyridyl, N-methylpyrrolyl, N-methylimidazolyl, quinolyl, furyl or thiofuranyl.

3. The pyrazine phosphine ligand compound according to claim 1, characterized in that: The pyrazine phosphine ligand compound is characterized in that R3, R4 and R5 are each independently selected from any one of hydrogen, unsubstituted C1-C4 alkyl, halogen or nitro.

4. The pyrazine phosphine ligand compound according to claim 1, characterized in that: The pyrazine phosphine ligand compound includes any one of the following compounds L1 to L8:

5. A method for preparing a pyrazine phosphine ligand compound according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: (1) reacting a pyrazine compound, N,N,N,N-tetramethylethylenediamine, an alkaline salt and n-butyl lithium to obtain a pyrazine metal salt; (2) A pyrazine metal salt is reacted with a monochlorophosphine compound to obtain the pyrazine phosphine ligand compound.

6. The method for preparing a pyrazine phosphine ligand compound according to claim 5, characterized in that: In step (1), the structural formula of the pyrazine compound is shown in Formula A below: wherein R1', R2', R3 and R4 are each independently selected from hydrogen or substituted or unsubstituted alkyl; Preferably, in step (1), the alkaline salt is selected from sodium tert-butoxide and / or potassium tert-butoxide; Preferably, in step (1), the molar ratio of the pyrazine compound, N,N,N,N-tetramethylethylenediamine, alkaline salt and n-butyllithium is 1:(1.5-4):(2-9):(2-9); Preferably, in step (1), the reaction is carried out in an alkane solvent; Preferably, the alkane solvent is heptane; Preferably, in step (1), the reaction is carried out in the presence of a protective gas; Preferably, the protective gas comprises nitrogen and / or argon; Preferably, in step (1), the reaction temperature is 0 to 5°C, and the reaction time is 12 to 24 hours; Preferably, in step (1), the specific steps of the reaction are: Under a protective gas atmosphere, a pyrazine compound, N,N,N,N-tetramethylethylenediamine and an alkaline salt are dissolved in an alkane solvent, cooled, and then an alkane solution of n-butyl lithium is added dropwise to react to obtain a reaction solution; Preferably, in step (1), after the reaction is completed, the following post-treatment steps are further included: The reaction solution is filtered, washed and dried in sequence to obtain the pyrazine metal salt.

7. The method for preparing a pyrazine phosphine ligand compound according to claim 5, characterized in that: In step (2), the structural formula of the monochlorophosphine compound is shown in Formula B below: Wherein, R1 and R2 are each independently selected from any one of substituted or unsubstituted alkyl, substituted or unsubstituted silyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl or substituted or unsubstituted heteroaryl; Preferably, in step (2), the molar ratio of the pyrazine metal salt to the monochlorophosphine compound is 1:(2-9), preferably 1:2; Preferably, in step (2), the reaction is carried out in an alkane solvent and / or an ether solvent; Preferably, the alkane solvent is hexane; Preferably, the ether solvent is methyl tert-butyl ether; Preferably, in step (2), the reaction temperature is 0 to 30° C., and the reaction time is 12 to 20 h; Preferably, in step (2), the specific steps of the reaction are: The pyrazine metal salt is dissolved in an alkane solvent and / or an ether solvent, cooled, and then a monochlorophosphine compound is added dropwise to react to obtain a reaction solution; Preferably, the temperature for dropping the monochlorophosphine compound is below 5°C; Preferably, in step (2), the following post-treatment steps are further included after the reaction is completed: Water is added to the reaction solution to quench the reaction, and then the reaction solution is separated, the organic phase is dried, filtered, and the solvent is removed in vacuo to obtain a crude product; the crude product is slurried and filtered to obtain the pyrazine phosphine ligand compound.

8. Use of the pyrazine phosphine ligand compound according to any one of claims 1 to 4 in the preparation of a catalyst for olefin alkoxycarbonylation, olefin hydroformylation, hydrocarboxylation or hydrocyanation.

9. A composite catalyst, characterized in that: The composite catalyst comprises a coordinated metal center and a pyrazine phosphine ligand compound according to any one of claims 1 to 4; Wherein, the coordination metal center includes any one or a combination of at least two of iron, cobalt, nickel, ruthenium, rhodium, iridium or palladium: Preferably, the raw materials for preparing the composite catalyst include: the pyrazine phosphine ligand compound described in any one of claims 1 to 4, a metal precursor and an acidic auxiliary agent; Preferably, the metal precursor is selected from any one or a combination of at least two of an iron-containing compound, a cobalt-containing compound, a nickel-containing compound, a ruthenium-containing compound, a rhodium compound, an iridium-containing compound or a palladium-containing compound, preferably a cobalt-containing compound and / or a palladium-containing compound, preferably a palladium-containing compound; Preferably, the palladium-containing compound is selected from any one or a combination of at least two of palladium chloride, palladium acetate, palladium acetylacetonate or palladium dibenzylideneacetone; Preferably, the acid auxiliary agent includes any one of methanesulfonic acid, trifluoroacetic acid or p-toluenesulfonic acid or a combination of at least two thereof, preferably p-toluenesulfonic acid; Preferably, the molar ratio of the metal precursor, the pyrazine phosphine ligand compound and the acidic auxiliary agent is 1:(1-8):(0.5-1.2); Preferably, the raw materials for preparing the composite catalyst also include a solvent; Preferably, the solvent is methanol.

10. A method for alkoxycarbonylation of olefins, characterized in that: The alkene alkoxycarbonylation method comprises the following steps: In the presence of the composite catalyst according to claim 9, olefin, carbon monoxide and / or methanol undergo an alkoxycarbonylation reaction to obtain an alkoxycarbonylation product of the olefin; Preferably, the olefin is selected from any one or a combination of at least two of substituted or unsubstituted C2 to C20 olefins, preferably any one or a combination of at least two of ethylene, propylene, butene or n-hexene, preferably ethylene; Preferably, in the alkoxycarbonylation reaction system, the concentration of the pyrazine phosphine ligand compound in the composite catalyst is 500 to 2500 ppm, preferably 700 to 1500 ppm; Preferably, the molar ratio of the olefin to carbon monoxide is (1-2):1; Preferably, the temperature of the alkoxycarbonylation reaction is 70-110° C., and the pressure of the alkoxycarbonylation reaction is 1.0-2.5 MPa.

Images