Preparation method of (1, 5-cyclooctadiene) dichloroplatinum (II)

Abstract

The invention relates to the technical field of hydrogenation cyclization catalysts, and provides a preparation method of (1, 5-cyclooctadiene) dichloroplatinum (II). The preparation method comprises the following steps: dissolving potassium chloroplatinite in a first polar solvent to obtain a potassium chloroplatinite solution; and mixing the potassium chloroplatinite solution, a second polar solvent, an auxiliary agent and 1, 5-cyclooctadiene, and carrying out a coordination reaction to obtain the (1, 5-cyclooctadiene) dichloroplatinum (II). According to the invention, the polar solvent and the auxiliary agent are added in the coordination reaction, so that the coordination reaction can be promoted to be efficiently carried out under mild conditions, and the reaction efficiency and the product yield are improved. Results of the embodiment show that when the method is used for preparing the (1, 5-cyclooctadiene) dichloroplatinum (II), the reaction time is only 0.5 h, and the product yield can reach 93% or above. In addition, the method is simple in process, short in synthesis route, good in safety, cheap and easily available in raw materials and suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of hydrogenation and cyclization catalyst technology, and more particularly to a method for preparing (1,5-cyclooctadiene)dichloroplatinum(II). Background Technology

[0002] Allenynes hydrogenation cyclization reactions, as an important strategy for constructing complex carbocyclic and heterocyclic systems in modern organic synthesis, have shown great potential in the total synthesis of natural products and drug development. These reactions efficiently construct various cyclic frameworks by cyclizing allene-containing structural units with alkynes intramolecularly or intermolecularly under the action of transition metal catalysts. In recent years, with the deepening research on cyclic allene intermediates, scientists have discovered more challenging cyclization modes, providing new tools for synthetic chemistry.

[0003] In the field of Allenynes hydrogenation cyclization, the choice of catalyst is crucial. In traditional preparation methods, palladium catalysts dominate in these reactions, such as the Pd-catalyzed strained cyclic propadiene cyclization method, which uses a palladium catalyst to form two new bonds and one sp bond. 3 The central method is used to construct fused heterocyclic products. These reactions typically utilize aryl halides and cyclic allyl precursors as reaction partners, achieving efficient cyclization under palladium catalysis. Notably, this method has also successfully developed diastereoselective and enantioselective variants, enabling the precise synthesis of chiral molecules.

[0004] However, palladium catalysts face limitations in some Allenynes hydrogenation cyclization reactions, particularly when dealing with highly strained ring systems or sterically hindered substrates, where reaction efficiency and selectivity are often unsatisfactory. This challenge has prompted researchers to explore other transition metal catalysts, among which platinum-based catalysts have gradually attracted attention due to their unique electronic structure and coordination properties. Compared to palladium, platinum centers possess stronger electrophilicity and more stable metal-carbon bonds, giving them a significant advantage in certain cyclization reactions, especially in complex substrates involving tandem cyclization or sensitive functional groups.

[0005] The application of platinum catalysts in the Allenynes cyclization reaction initially focused on simple platinum salts (such as K₂PtCl₄) and chloroplatinic acid, but the activity and selectivity of these compounds were generally unsatisfactory. With a deeper understanding of organometallic chemistry, researchers began to design structurally well-defined platinum complexes to achieve higher catalytic efficiency and selectivity. (1,5-Cyclooctadiene)dichloroplatinum(II) has attracted widespread attention in this context, with advantages including ease of synthesis and processing, ligand tunability, and strong stereocontrol capabilities.

[0006] (1,5-Cyclooctadiene)dichloroplatinum(II) is mainly synthesized via a coordination reaction between platinum chloride or potassium platinum chloride and the ligand 1,5-cyclooctadiene (COD). However, the octahedral coordination structure formed by Pt(IV) and chloride ions in platinum chloride and potassium platinum chloride is stable with high coordination bond energy, while the ligand 1,5-cyclooctadiene, as a neutral bidentate olefin ligand, has a weak ability to coordinate and attack the Pt(IV) center. Therefore, in the synthesis of (1,5-cyclooctadiene)dichloroplatinum(II), the coordination reaction is usually long under mild conditions, resulting in low production efficiency and yield. Although the reaction time can be shortened under high pressure, the conditions are harsh and dangerous, making it unsuitable for industrial production.

[0007] In summary, there is an urgent need to provide a method for preparing (1,5-cyclooctadiene)dichloroplatinum(II) that is efficient, mild, and suitable for industrial production. Summary of the Invention

[0008] In view of this, the present invention provides a method for preparing (1,5-cyclooctadiene)dichloroplatinum(II). The preparation method provided by the present invention does not require high pressure, has mild reaction conditions, and produces high product yield, making it suitable for industrial production.

[0009] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A method for preparing (1,5-cyclooctadiene)dichloroplatinum(II) includes the following steps: Potassium chloride platinum is dissolved in a first polar solvent to obtain a potassium chloride platinum solution; The potassium chloroplatinate solution, a second polar solvent, an auxiliary agent, and 1,5-cyclooctadiene are mixed and subjected to a coordination reaction to obtain (1,5-cyclooctadiene)dichloroplatinum(II); the polar solvent includes an organic acid; the auxiliary agent includes one or more of inorganic acids and p-toluenesulfonic acid.

[0010] Preferably, the first polar solvent includes one or more of water, alcohol, dimethyl sulfoxide, and acetone.

[0011] Preferably, the alcohol includes one or both of methanol and ethanol.

[0012] Preferably, the volume ratio of the first polar solvent to the mass ratio of potassium chloroplatinate is 1~10 mL:1 g.

[0013] Preferably, the organic acid includes one or more of acetic acid, formic acid, and oxalic acid.

[0014] Preferably, the inorganic acid includes one or more of hydrochloric acid, hydrobromic acid, sulfuric acid, and solid hydrochloric acid.

[0015] Preferably, the volume ratio of the second polar solvent to the first polar solvent is 0.5~4:1; the volume ratio of the auxiliary agent to the molar amount of potassium chloroplatinate is 1~100mL:1mol.

[0016] Preferably, the second polar solvent is acetic acid, and the auxiliary agent is hydrochloric acid.

[0017] Preferably, the coordination reaction is carried out at a temperature of 60~120℃ for a time of 0.5~1h.

[0018] Preferably, the molar ratio of 1,5-cyclooctadiene to potassium chloroplatinate is 5~20:1.

[0019] This invention provides a method for preparing (1,5-cyclooctadiene)dichloroplatinum(II), comprising the following steps: dissolving potassium chloroplatinate in a first polar solvent to obtain a potassium chloroplatinate solution; mixing the potassium chloroplatinate solution, a second polar solvent, an auxiliary agent, and 1,5-cyclooctadiene to perform a coordination reaction to obtain the (1,5-cyclooctadiene)dichloroplatinum(II); the second polar solvent includes an organic acid; the auxiliary agent includes one or more of inorganic acids and p-toluenesulfonic acid. This invention uses an organic acid as a polar solvent and one or more of inorganic acids and p-toluenesulfonic acid as an auxiliary agent in the coordination reaction, which can promote the efficient progress of the coordination reaction without high pressure, thereby improving reaction efficiency and product yield. Example results show that the method of this invention for preparing (1,5-cyclooctadiene)dichloroplatinum(II) requires only 0.5 h of reaction time and achieves a product yield of over 93%.

[0020] In addition, the process of this invention is simple, the synthesis route is short, there is only one-step synthesis reaction and the reaction conditions are mild and safe. The raw materials used are all basic chemicals that are available on a large scale in the market, which are inexpensive and readily available, and are suitable for industrial mass production. Furthermore, this invention also reduces the generation and discharge of high-salt wastewater, and the reaction solvent can be recovered by distillation, which reduces safety and environmental risks. Attached Figure Description

[0021] Figure 1 The process flow diagram for preparing (1,5-cyclooctadiene)dichloroplatinum(II) according to the present invention is shown. Detailed Implementation

[0022] This invention provides a method for preparing (1,5-cyclooctadiene)dichloroplatinum(II), comprising the following steps: Potassium chloride platinum is dissolved in a first polar solvent to obtain a potassium chloride platinum solution; The potassium chloroplatinate solution, a second polar solvent, an auxiliary agent, and 1,5-cyclooctadiene are mixed and subjected to a coordination reaction to obtain (1,5-cyclooctadiene)dichloroplatinum(II); the second polar solvent includes an organic acid; the auxiliary agent includes one or more of inorganic acids and p-toluenesulfonic acid.

[0023] This invention dissolves potassium chloroplatinate in a first polar solvent to obtain a potassium chloroplatinate solution. In this invention, the first polar solvent preferably includes one or more of water, alcohol, dimethyl sulfoxide, and acetone; the alcohol preferably includes one or both of methanol and ethanol; preferably, the potassium chloroplatinate is heated and stirred in the first polar solvent until dissolved, then filtered, and the resulting filtrate is a potassium chloroplatinate solution; the volume ratio of the first polar solvent to the mass of potassium chloroplatinate is preferably 1~10 mL:1 g, specifically 4 mL:1 g, 6 mL:1 g, or 8 mL:1 g; the dissolution temperature is preferably 60~120℃, more preferably 80℃; the dissolution is preferably carried out under stirring conditions.

[0024] After obtaining the potassium chloroplatinate solution, the present invention mixes the potassium chloroplatinate solution, a second polar solvent, an auxiliary agent, and 1,5-cyclooctadiene (1,5-COD) for a coordination reaction to obtain (1,5-cyclooctadiene)dichloroplatinum(II) (Pt(1,5-COD)Cl2). In the present invention, the second polar solvent includes an organic acid; the organic acid preferably includes one or more of acetic acid, formic acid, and oxalic acid; the acetic acid is glacial acetic acid. In the present invention, the second polar solvent can be added in a conventional manner to control the concentration of raw materials in the reaction system, effectively reduce the occurrence of side reactions of raw materials, and improve the process conversion rate.

[0025] In this invention, the auxiliary agent preferably includes one or more of inorganic acids and p-toluenesulfonic acid; the inorganic acid preferably includes one or more of hydrochloric acid, hydrobromic acid, sulfuric acid and solid hydrochloric acid; the sulfuric acid is preferably dilute sulfuric acid; the concentration of the dilute sulfuric acid is preferably 4 mol / L; and the hydrochloric acid is preferably commercially available concentrated hydrochloric acid with a mass fraction of 36-38%.

[0026] In a specific embodiment of the present invention, the second polar solvent is preferably acetic acid, which can prevent the hydrolysis of potassium chloroplatinate; the auxiliary agent is preferably hydrochloric acid, which can prevent chloride ion decoupling.

[0027] In this invention, the volume ratio of the second polar solvent to the first polar solvent is preferably 0.5 to 4:1, and more preferably 1:1.

[0028] In this invention, the volume ratio of the auxiliary agent to the molar amount of potassium chloroplatinate is preferably 1~100mL:1mol, more preferably 5~30mL:1mol, and specifically can be 21mL:1mol, 17mL:1mol, 8.3mL:1mol or 12.5mL:1mol.

[0029] In this invention, the molar ratio of 5-cyclooctadiene to 1,5-cyclooctadiene is preferably 5 to 20:1, specifically 5:1, 6:1, 7:1, 8:1 or 16:1.

[0030] In this invention, the temperature of the coordination reaction is preferably 60~120℃, more preferably 80℃, and the time of the coordination reaction is preferably 0.5~1h; the coordination reaction can be carried out under normal pressure. In a specific embodiment of this invention, it is preferable to first add the second polar solvent and the auxiliary agent to the potassium chloroplatinate solution, then slowly add 1,5-cyclooctadiene, and then heat the reaction system to 60~120℃ to carry out the coordination reaction.

[0031] In this invention, the reaction formula for the coordination reaction is shown in Formula 1: Formula 1.

[0032] In this invention, the steps of preparing the potassium chloroplatinate solution and the coordination reaction are preferably carried out by a continuous reaction.

[0033] After the coordination reaction is completed, the present invention preferably stops heating, and then continues stirring until the solution decolorizes. The resulting reaction solution is then filtered, washed, and dried to obtain the target product. The washing is preferably performed sequentially with ice water and ethanol. The filtrate is preferably treated with hydrogen peroxide solution and then recovered as waste liquid. The concentration of the hydrogen peroxide solution is preferably 30 wt%, and the volume of the hydrogen peroxide solution is preferably 1-3% of the filtrate volume. The present invention uses hydrogen peroxide solution to decompose excess cyclodiene compounds in the filtrate. The waste liquid recovery method is preferably distillation.

[0034] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0035] Example 1 (1) Add 200g potassium chlorite (0.48mol) and 1.5L water to a glass container at room temperature, start stirring, heat to 80℃, filter after dissolution, and transfer the filtrate to a clean glass reaction vessel to obtain potassium chlorite solution; (2) Add 1.5 L of glacial acetic acid and 10 mL of hydrochloric acid to the potassium chloroplatinate solution, and slowly add 960 mL of 1,5-cyclooctadiene. After heating the reaction system to 80 °C again, react for 0.5 h. A white solid compound slowly precipitates in the reaction vessel. Stop heating and continue stirring until the solution decolorizes. Then, perform conventional vacuum filtration. During filtration, wash 3-4 times with ice water and ice ethanol. Dry the solid to obtain the target compound (1,5-cyclooctadiene) dichloroplatinum(II). The filtrate is treated with 30% hydrogen peroxide and then recycled as waste liquid.

[0036] This example yielded 170 g of (1,5-cyclooctadiene)dichloroplatinum(II) with a purity of 99% and a yield of 95.1%. Elemental analysis results were: C: 26.01%, H: 2.42%, Cl: 18.98%, Pt: 52.50%.

[0037] Example 2 (1) Add 100g potassium chloroplatinate (0.24mol) and 0.8L water to a glass container at room temperature, start stirring, heat to 80℃, filter after dissolution, and transfer the filtrate to a clean 2.5L glass reaction vessel to obtain potassium chloroplatinate solution; (2) Add 0.8 L of glacial acetic acid and 4 mL of hydrochloric acid to the potassium chloroplatinate solution, and slowly add 187 mL of 1,5-cyclooctadiene. After heating the reaction system to 80 °C again, react for 0.5 h. A white solid compound slowly precipitates in the reaction vessel. Stop heating and continue stirring until the solution decolorizes. Then, perform conventional vacuum filtration. During filtration, wash with ice water and ice ethanol 3-4 times. Dry the solid to obtain the target compound norbornene dichloroplatinum(II). Treat the filtrate with 30% hydrogen peroxide and then recover the waste liquid.

[0038] This example yielded 84.52 g of (1,5-cyclooctadiene)dichloroplatinum(II) with a purity of 99% and a yield of 94.4%. Elemental analysis results were: C: 25.17%, H: 2.93%, Cl: 19.57%, Pt: 52.33%.

[0039] Example 3 (1) Add 500g potassium chloroplatinate (1.20mol) and 2L water to a glass container at room temperature, start stirring, heat to 80℃, filter after dissolution, and transfer the filtrate to a clean 10L glass reaction vessel to obtain potassium chloroplatinate solution. (2) Add 2 L of glacial acetic acid and 15 mL of hydrochloric acid to the potassium chloroplatinate solution, and slowly add 1.168 L of 1,5-cyclooctadiene. After heating the reaction system to 80 °C again, react for 0.5 h. A white solid compound slowly precipitates in the reaction vessel. Stop heating and continue stirring until the solution decolorizes. Then, perform conventional vacuum filtration. Wash the solution 3-4 times with ice water and ice ethanol during filtration. Dry the solid to obtain the target compound norbornene dichloroplatinum(II). Treat the filtrate with 30% hydrogen peroxide and then recover the waste liquid.

[0040] In this example, 440.08 g of (1,5-cyclooctadiene)dichloroplatinum(II) was obtained with a purity of 99% and a yield of 98.5%. The elemental analysis results were: C: 26.95%, H: 2.42%, Cl: 18.74%, Pt: 51.89%.

[0041] Example 4 (1) Add 500g potassium chloroplatinate (1.20mol) and 2L water to a glass container at room temperature, start stirring, heat to 80℃, filter after dissolution, and transfer the filtrate to a clean 10L glass reaction vessel to obtain potassium chloroplatinate solution. (2) Add 1 L of formic acid and 10 mL of p-xanthenesulfonic acid to the potassium chloroplatinate solution, and slowly add 1.168 L of 1,5-cyclooctadiene. After heating the reaction system to 80 °C again, react for 0.5 h. A white solid compound slowly precipitates in the reaction vessel. Stop heating and continue stirring until the solution decolorizes. Then, perform conventional vacuum filtration. During filtration, wash with ice water and ice ethanol 3-4 times. Dry the solid to obtain the target compound norbornene dichloroplatinum(II). Treat the filtrate with 30% hydrogen peroxide and then recover the waste liquid.

[0042] This example yielded 419.8 g of (1,5-cyclooctadiene)dichloroplatinum(II) with a purity of 99% and a yield of 93.9%. Elemental analysis results were: C: 25.95%, H: 2.52%, Cl: 18.64%, Pt: 57.89%.

[0043] Comparative Example 1 (1) Add 5g of potassium chloroplatinate (12.05 mmol) and 20 mL of water to a 100 mL glass container at room temperature, start stirring, heat to 80℃, filter after dissolution, and transfer the filtrate to a clean 100 mL glass reaction container to obtain potassium chloroplatinate solution. (2) 14.8 mL of 1,5-cyclooctadiene was slowly added to a potassium chloroplatinate solution and reacted for 3 h at a reaction temperature of 80 °C. A white solid compound slowly precipitated in the reaction vessel. Heating was stopped and stirring was continued until the solution decolorized. Then, conventional vacuum filtration was performed, and the solution was washed 3-4 times with ice water and ice ethanol during filtration. The solid was dried to obtain the target compound (1,5-cyclooctadiene) dichloroplatinum(II). The filtrate was treated with 30% hydrogen peroxide and the waste liquid was recovered.

[0044] This comparative example yielded 2.64 g of (1,5-cyclooctadiene)dichloroplatinum(II) with a purity of 76% and a yield of 58.5%. Elemental analysis showed that C: 27.53%, H: 2.38%, Cl: 17.97%, and Pt: 52.12%.

[0045] Comparative Example 2 (1) Add 5g of potassium chloroplatinate (12.05 mmol) and 20 mL of water to a 100 mL glass container at room temperature, start stirring, heat to 80℃, filter after dissolution, and transfer the filtrate to a clean 100 mL glass reaction container to obtain potassium chloroplatinate solution. (2) After adding 20 mL of glacial acetic acid to the potassium chloroplatinate solution and waiting for the solution to become clear, slowly add 14.8 mL of 1,5-cyclooctadiene. React for 2 hours at a temperature of 80°C. A white solid compound slowly precipitates in the reaction vessel. Stop heating and continue stirring until the solution decolorizes. Then, perform conventional vacuum filtration, washing 3-4 times with ice water and ice ethanol during filtration. Dry the solid to obtain the target compound (1,5-cyclooctadiene) dichloroplatinum(II). Treat the filtrate with 30% hydrogen peroxide and then recover the waste liquid.

[0046] This comparative example yielded 2.92 g of (1,5-cyclooctadiene)dichloroplatinum(II) with a purity of 83% and a yield of 64.7%. Elemental analysis showed that C: 26.19%, H: 2.46%, Cl: 18.97%, and Pt: 52.38%.

[0047] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A process for the preparation of (1,5-cyclooctadiene)dichloro platinum (II) characterized in that, The method comprises the following steps: dissolving potassium chloroplatinite in a first polar solvent to obtain a potassium chloroplatinite solution; mixing the potassium chloroplatinite solution, a second polar solvent, an auxiliary agent and 1,5-cyclooctadiene for a coordination reaction to obtain (1,5-cyclooctadiene) dichloro platinum (II); the second polar solvent comprises an organic acid; the auxiliary agent comprises one or more of inorganic acid and p-toluenesulfonic acid.

2. The production method according to claim 1, characterized by, The first polar solvent comprises one or more of water, alcohol, dimethyl sulfoxide and acetone.

3. The production method according to claim 2, characterized by, The alcohol comprises one or both of methanol and ethanol.

4. The production method according to claim 1, characterized by, The volume ratio of the first polar solvent to the mass of potassium chloroplatinite is 1-10 mL:1 g.

5. The preparation method according to claim 1, characterized in that, The organic acid comprises one or more of acetic acid, formic acid and oxalic acid.

6. The method of claim 1, wherein, The inorganic acid comprises one or more of hydrochloric acid, hydrobromic acid, sulfuric acid and solid hydrochloric acid.

7. The preparation method according to claim 1, characterized in that, The volume ratio of the second polar solvent to the first polar solvent is 0.5-4:1; the volume ratio of the auxiliary agent to the molar amount of potassium chloroplatinite is 1-100 mL:1 mol.

8. The production method according to claim 1, 5, 6 or 7, characterized by, The second polar solvent is acetic acid, and the auxiliary agent is hydrochloric acid.

9. The method of claim 1, wherein, The temperature of the coordination reaction is 60-120 ℃, and the time is 0.5-1 h.

10. The method of claim 1, wherein, The molar ratio of 1,5-cyclooctadiene to potassium chloroplatinite is 5-20:1.

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