Method for synthesizing DCPTA (2-(4-chlorophenyl)-1-

Abstract

The invention discloses a visible-light-induced method for synthesizing DCPTA, which belongs to the technical field of organic synthesis, and comprises the following reaction steps: under a nitrogen atmosphere, sequentially adding o-dichlorobenzene, N, N-diethylaminoethanol, a novel metal iridium complex, a nickel catalyst and a solvent into a Schlenk tube, and reacting under the irradiation of a blue LED lamp at room temperature; determining whether the reaction system is terminated or not through a silica gel plate point plate; and after the reaction is ended, carrying out reduced pressure rotary evaporation, and carrying out silica gel column chromatography separation and purification to obtain the product DCPTA. The method for synthesizing the DCPTA through visible light induction has the advantages of cleanness, high efficiency, few side reactions and high reaction yield.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a method for synthesizing and increasing amines by inducing visible light. Background Art

[0002] DCPTA (2-(3',4'-dichlorophenoxy)triethylamine) was first discovered and developed by Yokoyama Henry, a researcher at the Fruit and Vegetable Chemistry Research Institute of the U.S. Department of Agriculture, in 1977. It is a new and highly effective plant growth regulator. It is an active substance with many excellent properties for plant growth and development: it effectively regulates the growth and development of plants by regulating the production of endogenous plant hormones in plants. It can greatly improve the photosynthetic efficiency of plants, thereby effectively increasing the yield of crops. In addition, crops treated with DCPTA also show strong stress resistance. In addition, due to its outstanding yield-increasing effect on a variety of crops, it is called a "miracle drug."

[0003]

[0004] At present, the synthesis method of increasing the production of amines usually uses 3,4-dichlorophenol as the starting material, and is synthesized through etherification, amine alkylation and other steps. The main methods are summarized as follows:

[0005] 1. One-step synthesis of increased amine using β-chlorotriethylamine hydrochloride as raw material

[0006]

[0007] The operation is simple, but β-chlorotriethylamine hydrochloride is prone to intramolecular cyclization under alkaline conditions to produce by-products and reduce the yield.

[0008] 2. Alkylation amination method

[0009]

[0010] The synthesis method has a long reaction time and produces a large amount of salt-containing organic wastewater during the reaction process, which is difficult to treat.

[0011] 3. Chloroacetic acid method

[0012]

[0013] This synthesis method has many steps and is relatively costly, so it is generally not adopted.

[0014] 4. Ethylene oxide ring opening method

[0015]

[0016] This synthesis method has many steps and the safety of ethylene oxide is poor.

[0017] Therefore, developing an efficient, green and environmentally friendly method to synthesize increased-yield amines has important theoretical and practical significance. Summary of the invention

[0018] The invention provides a safe, green and efficient new method for synthesizing increased production amines, aiming to solve the problems of more by-products, more waste water, low yield, many steps and poor safety in the current methods for synthesizing increased production amines.

[0019] In order to realize the above invention, the present invention uses o-dichlorobenzene and N,N-diethylaminoethanol as raw materials, uses a new metal iridium complex as a visible light catalyst, and a metal nickel compound as a synergistic catalyst to realize a one-step synthesis of increased amine by CO coupling reaction under the induction of visible light. The synthetic reaction is simple to operate, has mild conditions, high reaction yield, and is green and environmentally friendly.

[0020] The specific technical solutions of the present invention are as follows:

[0021] A visible light-induced method for synthesizing an increased-yield amine comprises the following reaction steps: in a nitrogen atmosphere, o-dichlorobenzene, N,N-diethylaminoethanol, a novel metal iridium complex, a nickel catalyst and a solvent are successively added into a Schlenk tube, and reacted under the irradiation of a blue LED lamp at room temperature; the reaction system is determined to be terminated by spotting on a silica gel plate; after the reaction is terminated, the reaction is subjected to reduced pressure rotary evaporation, and the product increased-yield amine is separated and purified by silica gel column chromatography to obtain the product.

[0022] Among them, a chemical reaction equation of a method for synthesizing and increasing amine production induced by visible light is as follows:

[0023]

[0024] The reaction mechanism of the visible light-induced amine production increase of the present invention is as follows:

[0025]

[0026] First, the new metal iridium complex of the visible light catalyst is excited to an excited state under the induction of visible light. The excited iridium complex has a high oxidation potential and can easily grab an electron from o-dichlorobenzene to form a metal iridium complex anion radical and an o-dichlorobenzene cation radical. Then the metal iridium complex anion radical is oxidized by metal nickel (Ni II ) The catalyst grabs an electron back to the ground state, and the photocatalytic cycle is completed. At the same time, the o-dichlorobenzene cation radical can react with the nucleophile N,N-diethylaminoethanol to produce a dienyl radical and eliminate the proton, which will be replaced by Ni I The complex captures and forms Ni IIIHydride, Ni III The hydride accepts the electron from the dienyl radical and generates Ni by proton attack. II , the nickel metal catalytic cycle is completed. During this process, the generated aromatic cation loses a proton to generate the target product, increased amine, and H2 is produced at the same time.

[0027] Wherein, the solvent is ethyl acetate, toluene, acetonitrile or dichloromethane.

[0028] The molar ratio of o-dichlorobenzene to N,N-diethylaminoethanol is (2-5):1.

[0029] Wherein, the structural formula of the novel metal iridium complex is as follows:

[0030]

[0031] Among them, the synthesis method of the new metal iridium complex is as follows: take a three-necked flask, add [(ppy)2Ir(μ-Cl))2Ir(ppy)2] and acetonitrile in sequence under a nitrogen atmosphere, heat and stir, then add an acetonitrile solution of AgBF4 under nitrogen protection, and reflux. After the reaction is completed, cool it, filter it, wash the solid with ether, and dry it to obtain a yellow powder [Ir(ppy)2(MeCN)2]BF4. Take another clean three-necked flask, add [Ir(ppy)2(MeCN)2]BF4, ligand 1,3-diphenylimidazole, potassium tert-butoxide and tetrahydrofuran in sequence under a nitrogen atmosphere, and reflux. After the reaction is completed, cool it, pour it into water, extract it with ether, dry it, rotary evaporate it, and recrystallize it to obtain a new metal iridium complex.

[0032] The molar ratio of the novel metal iridium complex to N,N-diethylaminoethanol is (0.0003-0.002):1.

[0033] Wherein, the nickel catalyst is NiCl2·Ligand, wherein the types of ligands include:

[0034]

[0035] The molar ratio of the nickel catalyst to N,N-diethylaminoethanol is (0.0003-0.002):1.

[0036] Wherein, the irradiation wavelength of the blue LED light is in the range of λ=450-490nm.

[0037] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0038] 1. The present invention adopts a method for synthesizing and increasing amine by visible light induction. The synthesis method is clean and efficient, has few side reactions and high reaction yield.

[0039] 2. The present invention uses o-dichlorobenzene and N,N-diethylaminoethanol as raw materials, and synthesizes the increased yield amine in one step under the induction of visible light. The reaction raw materials are cheap and easy to obtain, and the reaction steps are simple and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 1HNMR spectrum of the yield-increasing amine prepared in Example 1;

[0041] Figure 2 This is the LC spectrum of the yield-enhancing amine prepared in Example 1. DETAILED DESCRIPTION

[0042] The following embodiments are provided for a better understanding of the present invention, but are not limited to the best mode of implementation, and do not limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0043] Example 1 Synthesis of a novel metal iridium complex:

[0044] Take a three-necked flask, add [(ppy)2Ir(μ-Cl))2Ir(ppy)2] and acetonitrile in sequence under a nitrogen atmosphere, heat and stir, then add an acetonitrile solution of AgBF4 under nitrogen protection, and reflux. After the reaction is completed, cool it down, filter it, wash the solid with ether, and dry it to obtain a yellow powder [Ir(ppy)2(MeCN)2]BF4. Take another clean three-necked flask, add [Ir(ppy)2(MeCN)2]BF4, ligand 1,3-diphenylimidazole, potassium tert-butoxide and tetrahydrofuran in sequence under a nitrogen atmosphere, and reflux. After the reaction is completed, cool it down, pour it into water, extract it with ether, dry it, rotary evaporate it, and recrystallize it to obtain a new metal iridium complex.

[0045]

[0046] The data characterization of the new metal iridium complex is as follows:

[0047] 1H NMR (400MHz, CDCl3): (ppm) δ8.12(d,J=5.5Hz,1H),7.97(d,J=5.6Hz,1H),7.76( d,J=8.1Hz,1H),7.66(d,J=8.1Hz,1H),7.62(d,J=1.8Hz,1H),7.55-7.52(m,2H) ,7.43-7.37(m,2H),7.28-7.25(m,1H),7.01-6.95(m,3H),6.87-6.82(m,6H),6. 74-6.68(m,4H),6.57(t,J=7.2Hz,1H),6.30-6.27(m,2H),5.97(d,J=7.3Hz,1H). 13 C NMR (100MHz, CDCl3): (ppm) δ178.0,172.9,171.0,170.2,168.8,157.1,153 .4,152.2,147.9,143.5,143.1,139.2,138.9,134.4,133.8,132.3,130.3, 129.4,128.8,128.1,127.4,125.9,125.4,123.7,123.5,121.8,121.6,121 .4,121.1,119.5,119.1,118.6,118.2,115.8,110.5.HRMS(ESI)m / z:[M+H] + Calcd for C 37 H 28 IrN 4721.1943; Found 4721.1947.

[0048] Example 2-15 Study on the method of synthesizing amines induced by visible light

[0049]

[0050] Under nitrogen atmosphere, weighed o-dichlorobenzene (294-735 mg, 2.0-5.0 mmol), N,N-diethylaminoethanol (117 mg, 1.0 mmol), new metal iridium complex (0.0003-0.002 mmol), nickel catalyst (0.0003-0.002 mmol), solvent (10 mL) were added to a 25 mL Schlenk tube in sequence, and the reaction was carried out under the irradiation of a blue LED lamp (λ = 450-490 nm) at room temperature. The reaction system was detected by a silica gel plate spot plate (developing agent: petroleum ether: ethyl acetate = 5:1) and the reaction was terminated after 12 hours. The reaction was evaporated under reduced pressure and separated and purified by silica gel column chromatography (eluent: petroleum ether: ethyl acetate = 5:1) to obtain the target product increased yield amine.

[0051]

[0052] (1) o-dichlorobenzene (294 mg, 2.0 mmol), the visible light catalyst selected a new metal iridium complex (0.002 mmol), the metal catalyst selected NiCl2·Ligand (ligand selected L1, 0.002 mmol), the light source selected a blue LED lamp (λ = 450-490 nm), and the effect of different solvents on the reaction results was investigated. The results are shown in Table 1:

[0053] Table 1 Influence of solvent effect on experimental results of visible light induced synthesis of amines

[0054] Example Solvents Reaction yield (%) Example 2 Ethyl acetate 81 Example 3 Toluene 89 Example 4 Acetonitrile 85 Example 5 Dichloromethane 95

[0055] The results show that the target product, the increased yield amine, can be obtained with a good yield when using various reaction solvents, among which the reaction yield is the highest when using dichloromethane as the solvent, reaching 92%. The H spectrum of the increased yield amine prepared in Example 2 is shown in FIG. Figure 1 As shown, the C spectrum is as Figure 2 shown.

[0056] (2) o-dichlorobenzene (294 mg, 2.0 mmol), the visible light catalyst selected a new metal iridium complex, the metal catalyst selected NiCl2·Ligand (ligand selected L1), the light source selected a blue LED lamp (λ = 450-490 nm), and the solvent selected dichloromethane. The effects of the amount of visible light catalyst and metal catalyst on the reaction results were investigated. The results are shown in Table 2:

[0057] Table 2 Effect of catalyst dosage on experimental results of visible light-induced synthesis of increased amine yield The results show that a higher reaction yield can still be obtained after reducing the catalyst dosage.

[0058]

[0059] (3) o-dichlorobenzene (294 mg, 2.0 mmol), a new metal iridium complex (0.0003 mmol) was selected as the visible light catalyst, NiCl2·Ligand (0.0003 mmol) was selected as the metal catalyst, a blue LED light (λ=450-490 nm) was selected as the light source, and dichloromethane was selected as the solvent. The effects of different metal nickel catalyst ligands on the reaction results were investigated. The results are shown in Table 3:

[0060] Table 3 Effect of different metal nickel catalyst ligands on the experimental results of visible light induced synthesis of increased amine production

[0061]

[0062] The ligand selected in Example 9 is L2, the ligand selected in Example 9 is L3, and the ligand selected in Example 9 is L4.

[0063] The results show that good reaction yields can still be obtained when other metal nickel catalyst ligands are selected.

[0064] (4) o-dichlorobenzene (294 mg, 2.0 mmol), a new type of metal iridium complex (0.0003 mmol) was selected as the visible light catalyst, NiCl2·Ligand (ligand selected L1, 0.0003 mmol) was selected as the metal catalyst, and dichloromethane was selected as the solvent. The reaction of the catalyst being recyclable was investigated. The results are shown in Table 4:

[0065]

[0066] Table 4 Experimental results of catalyst recycling to synthesize amines for increasing production

[0067] The results show that in this reaction system, the catalyst novel metal iridium complex (0.0003mmol) and the metal catalyst selected NiCl2·Ligand (ligand selected L1, 0.0003mmol) can be recycled.

[0068] (5) The visible light catalyst selected a new metal iridium complex, the metal catalyst selected NiCl2·Ligand (ligand selected L1), the light source selected a blue LED lamp (λ=450-490nm), and the solvent selected dichloromethane. The effect of different amounts of o-dichlorobenzene on the reaction yield was investigated. The results are shown in Table 5:

[0069] Example o-Dichlorobenzene, mmol Reaction yield (%) Example 16 3.0 96 Embodiment 17 4.0 96 Embodiment 18 5.0 96

[0070] The results show that with the increase of the dosage of o-dichlorobenzene, the reaction yield increases, but with the increase of dosage, the increasing trend of the yield gradually slows down.

[0071] It can be seen from the results of (1)-(5) that in the present invention, the novel metal iridium complex (0.0003mmol) is used as a visible light catalyst, NiCl2·Ligand (ligand selection L1, 0.0003mmol) is used as a metal catalyst, a blue LED lamp (λ=450-490nm) is used as a reaction light source, and dichloromethane is used as a reaction solvent, which are the optimal reaction conditions for the reaction.

[0072] Example 19 Scale-up experiment of the visible light induced synthesis method for increasing amine production

[0073] Under nitrogen atmosphere, weighed o-dichlorobenzene (29.4g, 0.2mol), N,N-diethylaminoethanol (11.7g, 0.1mol), new metal iridium complex (0.03mmol), nickel catalyst L1 (0.03mmol), solvent (1L) were added to a 2.5L reaction bottle in sequence, and the reaction was carried out under the irradiation of a blue LED lamp (λ = 450-490nm) at room temperature. The reaction system was detected by a silica gel plate spot plate (developing agent: petroleum ether: ethyl acetate = 5:1) and the reaction was terminated after 12 hours. The solvent was evaporated by vacuum rotary evaporation, and then the target product increased production amine 24.5g was obtained by vacuum distillation with a yield of 93%.

[0074] Example 20 Scale-up experiment of the visible light induced synthesis method for increasing amine production

[0075] Under nitrogen atmosphere, weighed o-dichlorobenzene (73.5 g, 0.5 mol), N, N-diethylaminoethanol (11.7 g, 0.1 mol), new metal iridium complex (0.03 mmol), nickel catalyst L1 (0.03 mmol), solvent (1 L) were added to a 2.5 L reaction bottle in sequence, and the reaction was carried out under the irradiation of a blue LED lamp (λ = 450-490 nm) at room temperature. The reaction system was detected by a silica gel plate spot plate (developing agent: petroleum ether: ethyl acetate = 5:1) and the reaction was terminated after 8 hours. The solvent was evaporated by vacuum rotary evaporation, and then the target product, increased amine, 25.0 g, was obtained by vacuum distillation with a yield of 95%.

[0076] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention. The protection scope of the present invention is defined by the claims and their equivalent technical solutions.

Claims

1. A method for synthesizing and increasing amine production induced by visible light, characterized in that The method comprises the following reaction steps: in a nitrogen atmosphere, o-dichlorobenzene, N,N-diethylaminoethanol, a novel metal iridium complex, a nickel catalyst and a solvent are successively added into a Schlenk tube, and reacted under the irradiation of a blue LED light at room temperature; the reaction system is determined to be terminated by spotting on a silica gel plate; after the reaction is terminated, the reaction is subjected to reduced pressure rotary evaporation, and separation and purification are performed by silica gel column chromatography to obtain a product, the yield-increasing amine.

2. The method for synthesizing amines induced by visible light according to claim 1, characterized in that The chemical reaction equation is as follows:

3. The method for synthesizing and increasing amine by visible light induction according to claim 1, characterized in that: The solvent is ethyl acetate, toluene, acetonitrile or dichloromethane.

4. The method for synthesizing and increasing amine production induced by visible light according to claim 1, characterized in that: The molar ratio of o-dichlorobenzene to N,N-diethylaminoethanol is (2-5):

1.

5. The method for synthesizing and increasing amine by visible light induction according to claim 1, characterized in that: The structural formula of the novel metal iridium complex is as follows:

6. The method for synthesizing and increasing amine production induced by visible light according to claim 5, characterized in that: The feeding molar ratio of the novel metal iridium complex to N,N-diethylaminoethanol is (0.0003-0.002):

1.

7. The method for synthesizing and increasing amine production induced by visible light according to claim 1, characterized in that: The nickel catalyst is NiCl2·Ligand, wherein the types of ligands include: The molar ratio of the nickel catalyst to N,N-diethylaminoethanol is (0.0003-0.002):

1.

8. The method for synthesizing and increasing amine by visible light induction according to claim 1, characterized in that: The irradiation wavelength of the blue LED light is in the range of λ=450-490nm.

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