A green synthesis method for 1,3-conjugated diyne derivatives

Abstract

The present invention provides a green synthesis method for 1,3-conjugated diyne derivatives. This method belongs to the field of fine chemical technology. The key points of the technical solution of the present invention are: using copper nitrate and sodium chloropalladate as metal precursors, lysine as a dispersant, and preparing a CuPd / SiO2 nanoalloy catalyst through steps such as roasting and reduction. In the oxidative coupling reaction of terminal acetylenic compounds to produce 1,3-conjugated diyne derivatives, the catalyst has the characteristics of high activity, good selectivity, high stability, and easy separation and recycling. The catalytic system reaction does not require the use of any additives, has few side reactions, good substrate applicability, and high yield.

Description

Technical Field

[0001] The present invention relates to the technical field of fine chemicals, in particular to a green synthesis method of 1,3-conjugated diyne derivatives. Background Art

[0002] 1,3-Diynes are important building blocks for fine chemicals, pharmaceutical intermediates, and bioactive substances. The oxidative coupling reaction of terminal alkynes is considered the most direct and efficient method for preparing 1,3-diyne compounds.

[0003] Mack et al. developed a solvent-free, oxidant-free catalyst for the oxidative coupling of alkynes. They found that using polymer-supported tetrakis(triphenyl)phosphine palladium as a catalyst could produce high yields of coupled products in the oxidative coupling of terminal alkynes. However, without the addition of additional triphenylphosphine, the catalyst could only be recycled twice, and with the addition of excess triphenylphosphine, only five times, and the reactivity was significantly reduced.

[0004]

[0005] The Al(OH)3-loaded nanopalladium catalyst prepared by Wei et al. can obtain 1,3-diyne compounds under mild conditions. However, this catalyst requires the addition of sodium acetate as a base during the reaction and requires Ag2SO4 as a chemical oxidant.

[0006] Zhang reported the use of CuFe2O4 as a catalyst for the oxidative coupling of terminal alkynes, enabling the synthesis of a variety of symmetrical and asymmetrical 1,3-diynes under mild conditions in moderate yields. The catalyst could be recovered using a magnet and reused five times without significant loss of activity. However, this catalytic system required the addition of pyridine as a base.

[0007]

[0008] In the preparation method of 1,3-diyne derivatives in the patent application document (CN200610122182.5), palladium chloride, cuprous iodide and peroxide can be used to achieve the oxidative coupling reaction of terminal alkynes, but the catalyst in this system can only be recycled five times and the conversion rate is low.

[0009] In a preparation method of a 1,3-butadiyne catalytic system in a patent application document (CN201410209072.7), copper chloride and air are used as a catalyst and an oxidant, respectively. However, the catalytic system has poor cyclic stability and requires the addition of an inorganic base and a ligand 8-hydroxyquinoline.

[0010] Patent application (CN201510306425.X) describes a method for synthesizing 1,3-diyne compounds using a simple, efficient, and reusable copper catalyst system. Using an organic solvent and water as the reaction solvents, a catalytic system consisting of copper nitrate and Luviset Clear can efficiently convert terminal alkynes into 1,3-diyne compounds. However, the catalyst has poor compatibility with its substrates, resulting in low yields.

[0011]

[0012] In summary, most of the catalysts reported so far for the synthesis of 1,3-conjugated diyne derivatives are homogeneous catalytic systems and require the use of complex organic ligands and external bases, which leads to problems such as difficulty in catalyst recovery and the generation of alkaline waste, hindering their practical application. Summary of the Invention

[0013] The purpose of the present invention is to provide a green synthesis method for 1,3-conjugated diyne derivatives. The copper-palladium bimetallic alloy catalyst used in this method has high activity, high selectivity, good stability, green reaction conditions, and is environmentally friendly. It solves the problems of difficult recovery, added base, and complex ligands in existing catalytic systems.

[0014] The present invention is achieved in that:

[0015] Under the action of a copper-palladium (CuPd) bimetallic alloy catalyst, terminal alkyne compounds can be efficiently oxidatively coupled to 1,3-conjugated diyne compounds. The copper-palladium bimetallic alloy catalyst is prepared by the following method:

[0016] (a) Copper nitrate and sodium chloropalladate are used as metal precursors and lysine is used as a dispersant to prepare an aqueous solution.

[0017] (b) The metal is loaded onto the SiO2 carrier by impregnation method, and then the corresponding metal oxide precursor is obtained by high-temperature calcination.

[0018] (c) reducing the precursor obtained in step (b) with 10% H2 / N2 to obtain a CuPd bimetallic alloy catalyst; the total metal loading in the CuPd bimetallic alloy catalyst is 2-10 wt%.

[0019] The CuPd bimetallic alloy catalyst was screened using the following steps:

[0020] The oxidative coupling of phenylacetylene was used as a model reaction to evaluate the catalytic performance of the CuPd bimetallic alloy catalyst.

[0021] In step (a), the feeding ratio of Cu and Pd salts is 20:1 to 1:1, preferably 5:1.

[0022] In step (a), the molar ratio of total metal to lysine is 0.1:1 to 10:1, preferably 4.5:1.

[0023] In step (b), the total metal loading is 2 to 10 wt%, preferably 4 wt%.

[0024] In step (c), the calcination temperature of the catalyst precursor is 300-600°C, preferably 400°C; the reduction temperature of the catalyst precursor is 200-500°C, preferably 300°C.

[0025] The present invention adopts the following technical solution to solve the above technical problems: a green synthesis method of 1,3-conjugated diyne derivatives, comprising the following steps:

[0026] (d) Using the CuPd / SiO2 prepared above as a catalyst, the raw material terminal acetylenic compound and solvent are added to a reaction tube equipped with an oxygen balloon and heated to initiate the reaction.

[0027] (e) After a certain reaction time, the sample was taken out from the flask and analyzed by gas chromatography using a 30 m HP-5 capillary column.

[0028] (f) After each experiment, the catalyst and the reaction medium are separated by centrifugation, and the catalyst is retained and subjected to multiple centrifugation and vacuum drying processes for use in the next catalytic experiment. The terminal alkyne compound is an aromatic terminal alkyne, an aliphatic terminal alkyne, a cycloalkane terminal alkyne, or a heterocyclic terminal alkyne having an electron-withdrawing group and an electron-donating group.

[0029] In step (d), the solvent may be dimethyl sulfoxide, ethanol, N,N-dimethylformamide and toluene, preferably dimethyl sulfoxide; the amount of catalyst used is 1 to 10 mol%, preferably 6 mol%.

[0030] In step (d), the reaction temperature is 80-150°C, preferably 100°C.

[0031] In step (d), the bimetallic catalyst is Cu 20 Pd1-400, Cu 10 Pd1-400, Cu5Pd1-400, Cu1Pd1-400, the preferred catalyst is Cu5Pd1-400. 400 represents the calcination temperature.

[0032] In step (d), the terminal alkyne compound is an aromatic terminal alkyne, an aliphatic terminal alkyne, a cycloalkane terminal alkyne, or a heterocyclic terminal alkyne having an electron-withdrawing group and an electron-donating group.

[0033] The key to achieving efficient coupling of terminal alkynes in the present invention is the use of a CuPd bimetallic alloy catalyst. During the preparation of the catalyst, the ratio of Cu and Pd elements and the calcination temperature have a significant impact on the catalytic performance of the catalyst.

[0034] The catalyst system method of the present invention is simple, easy to control, environmentally friendly, low in manufacturing cost, highly stable and reusable, has wide applicability under mild, alkali-free and ligand-free conditions, and has important application prospects in the field of fine chemicals. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 a, b, c are the TEM images and particle size distribution diagrams of Cu5Pd1-400, respectively; d, e, f are the element mapping diagrams of Cu5Pd1-400, respectively.

[0036] Figure 2 a and b are catalyst Cu x Pd y -XRD pattern of T.

[0037] Figure 3 a, b, c, d are Cu x Pd y XPS spectrum of the -T catalyst.

[0038] Figure 4 The diagram shows the oxidative coupling reactions of different terminal alkynes.

[0039] Figure 5 a, b, and c are the effects of different catalysts on the oxidative coupling of phenylacetylene.

[0040] Figure 6 The yield of phenylacetylene after 10 cycles catalyzed by Cu5Pd1-400. DETAILED DESCRIPTION

[0041] The following embodiments are only used to more clearly illustrate the technical solution of the present invention and are therefore only used as examples and are not intended to limit the scope of protection of the present invention.

[0042] Example 1

[0043] The steps for preparing the catalyst are as follows:

[0044] Preparation of CuPd bimetallic alloy catalyst: 1 g SiO2 was dispersed into 100 mL aqueous solution of sodium chloropalladate and copper nitrate (total metal loading was 4 wt%) under ultrasonication, and then lysine aqueous solution (0.53 mol·L -1) was added to the above mixture (the molar ratio of metal to lysine was 4.5:1) and stirred for 30 minutes. The suspension was distilled under reduced pressure, and the obtained solid was ground and calcined in a muffle furnace for 3 hours to obtain a precursor. The precursor was placed in a 10% H2 / N2 reduction furnace and reduced at 300℃ for 2 hours to obtain a catalyst called Cu x Pd y -T (x, y represent the molar ratios of Cu and Pd, respectively, and T is the calcination temperature of the catalyst).

[0045] When the ratio of Cu to Pd in ​​the catalyst is 5:1 and the calcination temperature is 400℃, it is represented by Cu5Pd1-400. For the catalyst Cu5Pd1-400, its TEM image, particle size distribution map and mapping map are as follows: Figure 1 As shown. Figure 1 TEM images show that the bimetallic nanoparticles are uniformly dispersed on the SiO2 carrier, with an average diameter of 2.4nm and a lattice spacing of about 0.217nm, which is between the lattice spacing of the (111) crystal plane of Pd and the (111) crystal plane of Cu, indicating the formation of a CuPd alloy. Figure 1 The element distribution diagram shows that Pd and Cu are evenly distributed on the SiO2 carrier without aggregation.

[0046] Figure 2 The catalyst Cu x Pd y -T's XRD pattern. Figure 2 It can be seen that Cu 20 The XRD patterns of Pd1-400, Cu5Pd1-400 and Cu1Pd1-400 catalysts do not show any diffraction peak of Pd. Figure 2 In a, as the Pd content increases (1:1 to 20:1), the Cu(111) crystal plane diffraction peak shifts toward the Pd(111) crystal plane diffraction peak, and the shift increases with the increase of the Pd ratio, indicating that a CuPd bimetallic alloy is formed. Figure 2 In b, as the calcination temperature increases (300℃~600℃), the Cu(111) crystal plane diffraction peak shifts toward the Pd(111) crystal plane diffraction peak, and the displacement increases with the calcination temperature, indicating that a CuPd bimetallic alloy is formed.

[0047] Figure 3 The catalyst Cu x Pd y -T XPS spectrum. Figure 3 It can be seen that with the increase of Pd content and the rise of calcination temperature, the electron binding energy of the Cu2p peak of the Cu-Pd bimetallic alloy catalyst moves upward by 0.05-0.34 eV, which indicates that the addition of Pd changes the electronic structure of the surface Cu atoms, causing the electrons of Cu to transfer to Pd, generating positively charged Cu species.

[0048] Example 2

[0049] The solvent screening for the catalytic reaction was performed using the catalyst prepared in Example 1, and the steps were as follows:

[0050] A certain amount of CuPd bimetallic alloy catalyst, Cu5Pd1-400, was placed in a reaction tube under an oxygen balloon. Phenylacetylene (0.5 mmol) and solvent (reactions were performed in four different solvents: dimethyl sulfoxide, toluene, ethanol, and N,N-dimethylformamide) were then added to the reaction tube. The reaction tube was evacuated three times to completely fill it with oxygen, and the reaction was carried out at 100°C. Phenylacetylene was efficiently converted to the corresponding 1,3-diyne. This catalytic method is not limited to the oxidative coupling of phenylacetylene; it can also produce a variety of terminal alkyne coupling products. Figure 4 The diagram shows the oxidative coupling reactions of different terminal alkynes.

[0051] The reaction activity of Cu5Pd1-400 catalyst in different solvents was tested respectively, and the different solvents were: dimethyl sulfoxide, N,N-dimethylformamide, toluene, and ethanol.

[0052] Table 1 Yields of phenylacetylene to 1,3-diyne using the catalyst Cu5Pd1-400 of the present invention in different solvents

[0053]

[0054]

[0055] As can be seen from Table 1, the catalyst prepared by the present invention has a good catalytic effect on the oxidative coupling of terminal alkynes in dimethyl sulfoxide, with a maximum yield of 99%.

[0056] Example 3

[0057] The catalyst Cu was prepared according to the method in Example 1. x Pd y -T, and according to the method in Example 2, the catalyst Cu x Pd y The oxidative coupling reaction of phenylacetylene was carried out under the action of -T, and dimethyl sulfoxide was selected as the solvent. The final yield was as follows Figure 5 shown. Figure 5 The total metal loading of the catalysts shown in a and b was 4 wt%.

[0058] like Figure 5As shown in a, as the Pd / Cu value increases, the reaction yield shows a volcano-shaped distribution. By comparison, it can be seen that the catalyst Cu5Pd1-400 has the best activity. Under the action of the mixture of Cu catalyst and Pd catalyst, the reaction yield is only 7%, which also shows that the synergistic effect of the bimetallic catalyst in this application is the key to improving the catalyst activity. Figure 5 b It can be seen that the activity of the catalyst and the calcination temperature also show a volcano-shaped correlation. Among them, Cu5Pd1-400 has the highest catalytic activity, with a reaction yield of 99%, while Cu5Pd1-300 has the lowest activity, with a reaction yield of only 3%. The yields of Cu5Pd1-500 and Cu5Pd1-600 participating in the reaction are 53% and 52%, respectively. Based on the above results, Cu5Pd1-400 is concluded to be the optimal catalyst. Figure 5 In c, Cu5Pd1-400 catalysts with different loading amounts (2 to 10 wt%) were selected, and the catalytic results showed that the Cu5Pd1-400 catalyst with a loading amount of 4 wt% was the optimal catalyst.

[0059] Example 4

[0060] Cu5Pd1-400 catalyst, an aromatic terminal alkyne (0.5 mmol), and dimethyl sulfoxide (2 mL) were added to a reaction tube containing an oxygen balloon. The tube was pumped three times to completely fill with oxygen and then placed on a 100°C reaction block for reaction. After the reaction proceeded for a specified period of time, a sample was removed from the tube and analyzed by gas chromatography (GC 9790-Plus) using a 30 MHz HP-5 capillary column. The yield was 99%.

[0061] Example 5

[0062] Cu5Pd1-400 catalyst, a cycloalkane terminal alkyne (0.5 mmol), and dimethyl sulfoxide (2 mL) were added to a reaction tube containing an oxygen balloon. The reaction tube was pumped three times to completely fill it with oxygen and then placed on a 100°C reaction block for reaction. After the reaction proceeded for a specified period of time, samples were removed from the reaction tube and analyzed by gas chromatography (GC 9790-Plus) using a 30 MHz HP-5 capillary column. The yields were all 99%.

[0063] Example 6

[0064] Cu5Pd1-400 catalyst, aliphatic terminal alkyne (0.5 mmol), and dimethyl sulfoxide (2 mL) were added to a reaction tube containing an oxygen balloon. The tube was evacuated three times to completely fill it with oxygen and then placed on a 100°C reaction block for reaction. After the reaction proceeded for a specified period of time, samples were removed from the tube and analyzed by gas chromatography (GC 9790-Plus) using a 30 nm HP-5 capillary column. Yields were consistently above 90%.

[0065] Example 7

[0066] The Cu5Pd1-400 catalyst prepared in Example 1 was repeatedly used in the oxidative coupling reaction of phenylacetylene to investigate the stability of the catalyst. The results are shown in FIG. Figure 6 As shown. Figure 6 It can be seen that after the Cu5Pd1-400 catalyst prepared in Example 1 was reused 10 times, the yield of 1,3-diyne was still maintained at above 90%, showing excellent stability.

[0067] Figure 6 The relationship between the number of cycles of Cu5Pd1-400 in the oxidative coupling of phenylacetylene and the yield of 1,3-diyne is shown. The recovered catalyst was reused 10 times with no significant decrease in activity. These results demonstrate the excellent stability of the heterogeneous Cu5Pd1-400 catalyst.

[0068] Experimental results show that the catalytic system can be recycled multiple times while maintaining a high yield. Furthermore, the recycling process employed is simple, which will facilitate its industrial application.

[0069] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent replacements and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention should be included in the scope of protection of the invention.

Claims

1. A green synthesis method for 1,3-conjugated diyne derivatives, characterized in that: The method comprises the following steps: firstly preparing a CuPd bimetallic alloy catalyst; then adding the CuPd bimetallic alloy catalyst, phenylacetylene and dimethyl sulfoxide into an oxygen balloon reaction tube, and reacting at a temperature of 80-150°C; The preparation method of the CuPd bimetallic alloy catalyst is as follows: using copper nitrate and sodium chloropalladate as metal precursors and lysine as a dispersant, the CuPd metal is loaded onto SiO2 by an impregnation method, and the CuPd bimetallic alloy catalyst is prepared through a calcination and reduction process; the calcination temperature is 400°C and the time is 3 h.

2. The green synthesis method of 1,3-conjugated diyne derivatives according to claim 1, characterized in that: The total metal loading in the CuPd bimetallic alloy catalysts was 2–10 wt%.

3. The green synthesis method of 1,3-conjugated diyne derivatives according to claim 1, characterized in that: The molar ratio of copper nitrate to sodium chloropalladate is 20:1-1:

1.

4. The green synthesis method of 1,3-conjugated diyne derivatives according to claim 1, characterized in that: The molar ratio of copper palladium metal to lysine is 10:1-4.5:

1.

5. The green synthesis method of 1,3-conjugated diyne derivatives according to claim 1, characterized in that: The reduction temperature is 200-500℃, and the reduction time is 0-2 h.

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