Iridium-containing Lewis base catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalysts, in particular to an iridium-containing Lewis base catalyst and a preparation method and application thereof.The preparation method comprises the following steps that iridium chloride is dissolved in oxygen-free water, a ligand compound is added into a system, the temperature is increased to 75-79 DEG C, a reducing agent is dropwise added into the system while stirring is conducted till no sediment is generated, washing is conducted with oxygen-free water after filtering, and the iridium-containing Lewis base catalyst is obtained; the structure of the ligand compound is as shown in the formula I: # imgabs0 #. The catalyst disclosed by the invention is simple in synthesis method, relatively good in catalytic efficiency, and capable of reducing the synthesis temperature and time.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts, and in particular to an iridium-containing Lewis base catalyst and a preparation method and application thereof. Background Art

[0002] Glufosinate is a widely used, efficient, broad-spectrum, low-toxic, non-selective organophosphorus contact herbicide, including L and DL glufosinate, of which L-glufosinate is the main herbicide, so the herbicide effect of DL-glufosinate is weak. At present, a large number of researchers have proposed many methods for preparing glufosinate, such as WO2022 / 077989A1 "L-glufosinate preparation method" uses L-4-chloro-2-aminobutyric acid ethyl ester and chloromethyl phosphite ethyl ester (referred to as MCP) to synthesize a five-membered ring structure intermediate (referred to as MPO), and then hydrolyze to obtain refined glufosinate. Another example is CN116789695A "a method for preparing glufosinate" uses methyl dichloride to first prepare an intermediate with methyl dimethylamine or methyl diethylamine, and then reacts with L-4-chloro-2-aminobutyric acid ethyl ester to prepare a five-membered ring intermediate, and then hydrolyzes to obtain refined glufosinate.

[0003] Previously, the applicant disclosed in CN117964655A a "method for synthesizing L-glufosinate-ammonium", which has a simple synthesis process, wherein the compound represented by formula (V)

[0004] The reaction with diethyl methyl phosphite is the first step in the preparation of refined glufosinate ammonium, which refers to the nucleophilic substitution reaction and is also a particularly important step. With the continuous deepening of research and development, the applicant found that the experimental conditions in this step are harsh, and it is often necessary to still need a high temperature and negative pressure state in the presence of a catalyst to ensure the smooth progress of the reaction.

[0005] Catalysts are substances that can increase the reaction rate and selectivity in chemical reactions but are not consumed during the reaction process. They accelerate reactions by providing reaction pathways with lower activation energy. Compared with traditional catalysts, new catalysts are a type of catalyst that exhibits higher activity, selectivity and stability in catalytic reactions. These catalysts are prepared by carefully designing and regulating the composition, structure and surface properties of the catalysts.

[0006] In the above disclosed steps, the applicant often uses conventional 2,4,6-trimethylpyridine. Although it can successfully synthesize intermediate compounds, the harsh experimental conditions limit its application and the catalyst effect is not ideal. Therefore, it is urgent to develop a catalyst with high catalytic efficiency and the ability to reduce reaction temperature and time. Summary of the invention

[0007] The main purpose of the present invention is to provide an iridium-containing Lewis base catalyst and a preparation method and application thereof. The synthesis method of the catalyst is simple, has good catalytic efficiency, and can reduce the synthesis temperature and time.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] On one hand, the present invention provides a method for preparing an iridium-containing Lewis base catalyst, comprising the following steps: dissolving iridium chloride in oxygen-free water, adding a ligand compound into the system, heating the system to 75-79° C., adding a reducing agent dropwise into the system while stirring until no precipitation is generated, filtering, washing with oxygen-free water, and drying to obtain the iridium-containing Lewis base catalyst;

[0010] The structure of the ligand compound is shown in Formula I:

[0011]

[0012] The present application adopts a self-made ligand and metallic iridium for coordination to form an octahedral iridium complex catalyst, which can efficiently catalyze the nucleophilic substitution reaction, shorten the time and temperature of the nucleophilic substitution reaction, and improve the synthesis efficiency of glufosinate ammonium. At the same time, the catalyst of the present application is more stable during catalysis, further improving the catalytic efficiency. The reason may be that, on the one hand, iridium can produce hydrogen bonds and other effects with the ligand to form a stable octahedral structure. In addition, the phenyl structure contained in the ligand can form π-π stacking, which further improves the stability of the catalyst, making it more stable during use and thus improving the catalytic stability and efficiency; on the other hand, the iridium in the catalyst and the pyridine structure in the ligand can produce a synergistic effect, and have a stronger ability to bind to the transition state of the reactant in the nucleophilic substitution reaction, thereby promoting the reaction.

[0013] In some embodiments, the molar ratio of the iridium chloride to the ligand compound is 1:(3-3.2).

[0014] Preferably, the molar ratio of iridium chloride to the ligand compound is 1:3.1.

[0015] The present invention regulates the molar ratio of iridium chloride to the ligand compound to enable iridium to form a stable octahedral coordination structure, thereby further improving the catalytic efficiency.

[0016] In some embodiments, the reducing agent is potassium borohydride and / or sodium borohydride.

[0017] In some embodiments, the method for preparing the ligand compound comprises the following steps:

[0018] S1. Mix 2-naphthocarbonitrile and 4-hydroxyquinoline-8-carbonitrile, add the first solvent, add NaH in batches at -5 to 0°C, then heat to 40 to 50°C and stir at constant temperature for 20 to 22 hours. After the reaction is completed, quench, extract, combine the organic phases, dry and then perform column chromatography to obtain compound A, the structure of which is shown in Formula II.

[0019]

[0020] S2, compound A in step S1 and the second solvent are mixed, hydrogen is introduced, the temperature is raised to 35-45°C and stirred at a constant temperature for 5-7 hours, and after the reaction is completed, compound B is obtained, the structure of which is shown in formula III

[0021]

[0022] S3, 4-pyridineacetic acid and thionyl chloride were mixed and stirred at -5 to 0°C for 3 to 5 hours, and after the reaction, the mixture was quenched, extracted, concentrated and dried under reduced pressure to obtain compound C, the structure of which is shown in Formula IV

[0023]

[0024] S4, mixing the compound C in step S3, the compound B in step S2 and the third solvent, adding an acid binding agent, stirring at room temperature for 1 to 2 hours, filtering after the reaction, and performing column chromatography to obtain a ligand compound.

[0025] The ligand compound of the present application contains a large number of ionic bonds, hydrogen bonds and coordination bonds, which can make iridium form a more stable octahedral structure, thereby improving the stability of the catalyst during use. At the same time, the phenyl groups therein can form π-π stacking to further improve the high temperature resistance and structural stability of the catalyst, thereby improving the catalytic efficiency. In addition, the ligand contains a large number of pyridine structures, which can increase the basicity of the catalyst and can cooperate with iridium to catalyze nucleophilic substitution reactions.

[0026] In some embodiments, in step S1, the molar ratio of 2-naphthocarbonitrile to 4-hydroxyquinoline-8-carbonitrile is 1:(1-1.5).

[0027] Preferably, in step S1, the molar ratio of 2-naphthocarbonitrile to 4-hydroxyquinoline-8-carbonitrile is 1:1.2.

[0028] The present application can improve the yield of compound A and avoid the waste of raw materials by regulating the molar ratio of 2-naphthocarbonitrile and 4-hydroxyquinoline-8-carbonitrile.

[0029] In some embodiments, in step S3, the molar ratio of 4-pyridineacetic acid to thionyl chloride is 1:(2-5).

[0030] Preferably, in step S3, the molar ratio of 4-pyridineacetic acid to thionyl chloride is 1:3.

[0031] In some embodiments, in step S4, the molar ratio of compound C to compound B is (2-2.3):1.

[0032] Preferably, in step S4, the molar ratio of compound C to compound B is 2.1:1.

[0033] In some embodiments, the first solvent is any one of tetrahydrofuran, toluene and ethanol; the second solvent is aqueous ammonia; and the third solvent is any one of N,N-dimethylformamide, tetrahydrofuran, methanol, ethanol and toluene.

[0034] In some embodiments, in step S1, the volume of the first solvent is 5 to 8 times the total mass of 2-naphthocarbonitrile and 4-hydroxyquinoline-8-carbonitrile.

[0035] In some embodiments, in step S2, the volume of the second solvent is 45 to 55 times the mass of compound A.

[0036] In some embodiments, in step S4, the volume of the third solvent is 8 to 10 times the total mass of compound C and 4-pyridineacetic acid.

[0037] In some embodiments, the acid binding agent is any one of potassium bicarbonate, sodium bicarbonate, potassium carbonate, sodium carbonate and triethylamine.

[0038] In some embodiments, in step S4, the molar ratio of the acid-binding agent compound C is (2-2.2):1.

[0039] Another aspect of the present invention provides an iridium-containing Lewis base catalyst prepared by the above scheme.

[0040] In another aspect, the present invention provides an application of an iridium-containing Lewis base catalyst in a nucleophilic substitution reaction.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The iridium-containing Lewis base catalyst of the present invention adopts a self-made ligand and metal iridium to coordinate to form an octahedral iridium complex catalyst, wherein the iridium can produce hydrogen bonds and the like with the ligand to form a stable octahedral structure. In addition, the phenyl structure contained in the ligand can form π-π stacking, which further improves the stability of the catalyst, making it more stable during use and thus improving the catalytic stability and efficiency; on the other hand, the iridium in the catalyst and the pyridine structure in the ligand can produce a synergistic effect, and the ability to bind to the transition state of the reactant in the nucleophilic substitution reaction is stronger, thereby promoting the reaction.

[0043] (2) The ligand compound of the present invention contains a large number of ionic bonds, hydrogen bonds and coordination bonds, which can make iridium form a more stable octahedral structure, thereby improving the stability of the catalyst during use. At the same time, the phenyl groups therein can form π-π stacking to further improve the high temperature resistance and structural stability of the catalyst, thereby improving the catalytic efficiency. In addition, the ligand contains a large number of pyridine structures, which can increase the basicity of the catalyst and can cooperate with iridium to catalyze nucleophilic substitution reactions.

[0044] (3) The present invention uses a specific molar ratio of iridium chloride and ligand compound to enable iridium to form a stable octahedral coordination structure, thereby further improving the catalytic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0046] Figure 1 is the nuclear magnetic resonance spectrum of compound A in Preparation Example 1;

[0047] Figure 2 is the nuclear magnetic resonance spectrum of compound B in Preparation Example 1;

[0048] Figure 3 is the nuclear magnetic resonance spectrum of compound C in Preparation Example 1;

[0049] Figure 4 This is the nuclear magnetic resonance spectrum of the ligand compound in Preparation Example 1. DETAILED DESCRIPTION

[0050] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not 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.

[0051] Preparation Example 1

[0052] The preparation method of the ligand compound comprises the following steps:

[0053] S1. Mix 14.1 g of 2-naphthocarbonitrile and 15.6 g of 4-hydroxyquinoline-8-carbonitrile, add 210 mL of tetrahydrofuran, add 0.22 g of NaH in batches at -3 °C, then heat to 45 °C and stir for 21 h. After the reaction is completed, quench, extract, combine the organic phases, dry and pass column chromatography to obtain compound A, the structure of which is shown in Formula II

[0054] The yield is 52.1%;

[0055] according to Figure 1 It can be seen that the NMR data analysis of compound A is as follows: 1 H NMR(500MHz,)δ8.81(d,J=5.0Hz,1H),8.42-8.30(m,2H),8.06-7.93(m,1H),7.92-7.84(m,1H),7. 67(dd,J=5.0,2.3Hz,1H),7.55-7.45(m,2H),7.23(dd,J=10.03,2.5Hz,1H),7.12(d,J=5.0Hz,1H);

[0056] S2. Mix 15.4 g of compound A in step S1 and 800 mL of ammonia water, introduce hydrogen, heat to 40° C. and stir for 6 h. After the reaction, obtain compound B, the structure of which is shown in Formula III.

[0057] The yield is 89.8%;

[0058] according to Figure 2 It can be seen that the NMR data analysis of compound B is as follows: 1 H NMR(500MHz,)δ8.62(d,J=5.0Hz,1H),8.14(dd,J=10.0,1.3Hz,1H),7.86(ddd ,J=10.0,8.1,2.0Hz,2H),7.72-7.68(m,1H),7.47(dd,J=10.0,1.3Hz,1H),7.4 4-7.35(m,3H),7.11(dd,J=10.0,2.4Hz,1H),7.06(d,J=5.0Hz,1H),4.31(q,J= 5.0Hz,1H),4.22-4.12(m,3H),4.03-3.94(m,3H),3.90(td,J=5.0,5.8Hz,1H);

[0059] S3, 14.0g 4-pyridineacetic acid and 36.4g thionyl chloride were mixed and stirred at -3°C for 4h, quenched after the reaction, extracted, concentrated and dried under reduced pressure to obtain compound C, the structure of which is shown in Formula IV

[0060] The yield is 98.6%;

[0061] according to Figure 3 It can be seen that the NMR data analysis of compound C is as follows: 1H NMR(500MHz,)δ8.65-8.45(m,1H),7.33-7.08(m,1H),4.40(d,J=15.0Hz,1H),4.12(d,J=10.0Hz,0H);

[0062] S4, 15.56g of compound C in step S3, 15.8g of compound B in step S2 and 282mL of N,N-dimethylformamide were mixed, 21g of potassium bicarbonate was added, and the mixture was stirred at a constant temperature of 27°C for 1.5h. After the reaction was completed, the mixture was filtered and subjected to column chromatography to obtain a ligand compound with a yield of 95.2%. The total yield of the ligand compound was calculated to be 46.1%.

[0063] according to Figure 4 It can be seen that the NMR data analysis of the ligand compound is as follows: 1 H NMR(500MHz,)δ8.62(d,J=5.0Hz,1H),8.59-8.54(m,4H),8.27-8.19(m,2H),8.14(d d,J=10.0,1.3Hz,1H),7.72(dd,J=10.0,1.2Hz,2H),7.69-7.65(m,1H),7.51(dd,J= 10.0,1.3Hz,1H),7.45-7.33(m,3H),7.20(dd,J=10.0,1.9Hz,1H),7.17-7.12(m,3H ), 7.06 (d, J = 5.0Hz, 1H), 4.84 (d, J = 5.0Hz, 2H), 4.36 (d, J = 5.0Hz, 2H), 3.62 (s, 4H).

[0064] Preparation Example 2

[0065] The preparation method of the ligand compound is the same as that of Preparation Example 1, except that 4-hydroxyquinoline-8-carbonitrile is 7.7 g, and the yield of compound A is 38.6%. The total yield of the ligand compound is calculated to be 33%.

[0066] Preparation Example 3

[0067] The preparation method of the ligand compound is the same as that of Preparation Example 1, except that thionyl chloride is 18.2 g, and the yield of compound C is 88.2%. The total yield of the ligand compound is calculated to be 46.3%.

[0068] Preparation Example 4

[0069] The preparation method of the ligand compound is the same as that of Preparation Example 1, except that the compound B is 21 g, the yield of the ligand compound is 54.6%, and the total yield of the ligand compound is calculated to be 25.5%.

[0070] Preparation Example 5

[0071] The specific implementation method of the ligand compound is the same as that of Preparation Example 1, except that an equal molar amount of p-methylphenylacetic acid is used instead of 4-pyridineacetic acid.

[0072] Preparation Example 6

[0073] The preparation method of the ligand compound is the same as that of Preparation Example 1, except that an equimolar amount of the compound represented by Formula VI is used.

[0074] Replace compound A;

[0075] The preparation method of the compound represented by formula VI comprises the following steps: 50 mmol of chloroacetonitrile and 60 mmol of 4-hydroxyquinoline-8-carbonitrile are mixed, 130 mL of N,N-dimethylformamide and 70 mmol of potassium bicarbonate are added, the temperature is raised to 75° C. and stirred at a constant temperature for 4 hours. After the reaction is completed, the mixture is concentrated and dried under reduced pressure, and the compound represented by formula VI is obtained by column chromatography.

[0076] Example 1

[0077] A preparation method of an iridium-containing Lewis base catalyst comprises the following steps: dissolving 15.8 g of iridium chloride in 1 L of oxygen-free water, adding 88 g of a ligand compound into the system, heating the system to 77° C. and dripping a 12 wt % sodium borohydride solution into the system while stirring until no precipitation is generated, filtering, washing with oxygen-free water, and drying to obtain the iridium-containing Lewis base catalyst;

[0078] The structure of the ligand compound is shown in Formula I:

[0079]

[0080] Wherein, the ligand compound is prepared by Preparation Example 1.

[0081] Example 2

[0082] A preparation method of an iridium-containing Lewis base catalyst comprises the following steps: dissolving 15.8 g of iridium chloride in 1 L of oxygen-free water, adding 85 g of a ligand compound into the system, heating the system to 75° C. and dripping a 12 wt % sodium borohydride solution into the system while stirring until no precipitation is generated, filtering, washing with oxygen-free water, and drying to obtain the iridium-containing Lewis base catalyst;

[0083] The structure of the ligand compound is shown in Formula I:

[0084]

[0085] Wherein, the ligand compound is prepared by Preparation Example 1.

[0086] Example 3

[0087] A preparation method of an iridium-containing Lewis base catalyst comprises the following steps: dissolving 15.8 g of iridium chloride in 1 L of oxygen-free water, adding 91 g of a ligand compound into the system, heating the system to 79° C. and dripping a 12 wt % sodium borohydride solution into the system while stirring until no precipitation is generated, filtering, washing with oxygen-free water, and drying to obtain the iridium-containing Lewis base catalyst;

[0088] The structure of the ligand compound is shown in Formula I:

[0089]

[0090] Wherein, the ligand compound is prepared by Preparation Example 1.

[0091] Example 4

[0092] A method for preparing an iridium-containing Lewis base catalyst, the specific implementation method is the same as Example 1, except that the ligand compound is prepared by Preparation Example 2.

[0093] Example 5

[0094] A method for preparing an iridium-containing Lewis base catalyst, the specific implementation method is the same as Example 1, except that the ligand compound is prepared by Preparation Example 3.

[0095] Example 6

[0096] A method for preparing an iridium-containing Lewis base catalyst, the specific implementation method is the same as Example 1, except that the ligand compound is prepared by Preparation Example 4.

[0097] Comparative Example 1

[0098] A method for preparing an iridium-containing Lewis base catalyst, the specific implementation method is the same as Example 1, except that the ligand compound is prepared by Preparation Example 5.

[0099] Comparative Example 2

[0100] A method for preparing an iridium-containing Lewis base catalyst, the specific implementation method is the same as Example 1, except that the ligand compound is prepared by Preparation Example 6.

[0101] Comparative Example 3

[0102] A method for preparing an iridium-containing Lewis base catalyst, the specific implementation method is the same as that of Example 1, except that an equimolar amount of compound B is used instead of the ligand compound.

[0103] Performance Testing:

[0104] Under N2 atmosphere, 100g of the compound represented by formula I and 200mL of chlorobenzene were mixed and stirred evenly, and 0.03mol of iridium-containing Lewis base catalyst and 90.41g of diethyl methyl phosphite were added dropwise to the system. The mixture was heated to 60°C and stirred for 12h under normal pressure. After the reaction was completed, the mixture was distilled under reduced pressure at a pressure of 0.11MPa and a distillation temperature of 50°C to obtain a mixture of the compound represented by formula VI-1 and the compound represented by VI-2.

[0105]

[0106] The iridium-containing Lewis base catalysts in the above examples and comparative examples were used in the above reaction, and the total yields of the compound represented by formula VI-1 and the compound represented by formula VI-2 were calculated, as shown in Table 1.

[0107] Table 1

[0108] Total yield (%) Example 1 97.3 Example 2 96.9 Example 3 97.6 Example 4 97.2 Example 5 96.6 Example 6 96.8 Comparative Example 1 81.2 Comparative Example 2 83.6 Comparative Example 3 81.9

[0109] From the analysis of the data in Table 1, it can be seen that the catalysts prepared in Examples 1 to 3 have low catalytic temperatures and short catalytic times, and have good catalytic performance and stability; although the catalytic performance of Examples 4 to 6 is comparable to that of Examples 1 to 3, the yield of the ligands therein is low during the preparation process; in Comparative Example 1, the catalytic efficiency of the catalyst is reduced due to the use of equimolar p-methylphenylacetic acid instead of 4-pyridineacetic acid; in Comparative Example 2, the stability of the catalyst is reduced due to the use of equimolar compounds represented by formula VI instead of compound A, thereby affecting the catalytic efficiency; in Comparative Example 3, the pyridine structure is reduced due to the use of equimolar compound B instead of the ligand compound, resulting in a weakened catalytic performance of the catalyst.

[0110] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing an iridium-containing Lewis base catalyst, characterized in that: The method comprises the following steps: dissolving iridium chloride in oxygen-free water, adding a ligand compound into the system, heating the system to 75-79° C., adding a reducing agent dropwise into the system while stirring until no precipitation is generated, filtering, washing with oxygen-free water, and drying to obtain an iridium-containing Lewis base catalyst; The structure of the ligand compound is shown in Formula I:

2. The method for preparing an iridium-containing Lewis base catalyst according to claim 1, wherein The molar ratio of the iridium chloride to the ligand compound is 1:(3-3.2).

3. The method for preparing an iridium-containing Lewis base catalyst according to claim 1, wherein: The reducing agent is potassium borohydride and / or sodium borohydride.

4. The method for preparing an iridium-containing Lewis base catalyst according to claim 1, wherein: The preparation method of the ligand compound comprises the following steps: S1. Mix 2-naphthocarbonitrile and 4-hydroxyquinoline-8-carbonitrile, add the first solvent, add NaH in batches at -5 to 0°C, then heat to 40 to 50°C and stir at constant temperature for 20 to 22 hours. After the reaction is completed, quench, extract, combine the organic phases, dry and then perform column chromatography to obtain compound A, the structure of which is shown in Formula II. S2, compound A in step S1 and the second solvent are mixed, hydrogen is introduced, the temperature is raised to 35-45°C and stirred at a constant temperature for 5-7 hours, and after the reaction is completed, compound B is obtained, the structure of which is shown in formula III S3, 4-pyridineacetic acid and thionyl chloride were mixed and stirred at -5 to 0°C for 3 to 5 hours, and after the reaction, the mixture was quenched, extracted, concentrated and dried under reduced pressure to obtain compound C, the structure of which is shown in Formula IV S4, mixing the compound C in step S3, the compound B in step S2 and the third solvent, adding an acid binding agent, stirring at room temperature for 1 to 2 hours, filtering after the reaction, and performing column chromatography to obtain a ligand compound.

5. The method for preparing an iridium-containing Lewis base catalyst according to claim 4, characterized in that: In step S1, the molar ratio of 2-naphthocarbonitrile to 4-hydroxyquinoline-8-carbonitrile is 1:(1-1.5).

6. The method for preparing an iridium-containing Lewis base catalyst according to claim 4, characterized in that: In step S3, the molar ratio of 4-pyridineacetic acid to thionyl chloride is 1:(2-5).

7. The method for preparing an iridium-containing Lewis base catalyst according to claim 4, characterized in that: In step S4, the molar ratio of compound C to compound B is (2-2.3):

1.

8. The method for preparing an iridium-containing Lewis base catalyst according to claim 4, characterized in that: In step S4, the molar ratio of the acid binding agent to compound C is (2-2.2):

1.

9. An iridium-containing Lewis base catalyst obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the iridium-containing Lewis base catalyst according to claim 9 in a nucleophilic substitution reaction.

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