Preparation method of palladium acetate tripolymer
By reacting sponge palladium and methyl iodide with CO2 under low temperature conditions, the problems of by-product generation and process complexity in the traditional palladium acetate preparation method are solved, and high-purity and high-yield palladium acetate trimer preparation is achieved, which improves catalyst activity and reduces production costs.
Patent Information
- Application Number
- CN202411839004.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-03-25
AI Technical Summary
In the traditional preparation method of palladium acetate, when using palladium black as the palladium source, nitrogen or chlorine atoms need to be introduced, resulting in the generation of by-products, affecting the activity of the catalyst and product quality, and the process is complex and the cost is high.
The reaction of sponge palladium and methyl iodide is carried out, and the reaction is carried out with CO2 under low temperature conditions, simplifying the process, avoiding the generation of by-products, and improving the purity and yield of palladium acetate trimer.
The preparation of palladium acetate trimers with high purity and high yield is achieved, which improves catalyst activity, simplifies the process flow, reduces production costs, and is environmentally friendly.
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Abstract
Description
Technical Field
[0001] The invention belongs to the field of fine chemicals, and in particular relates to a method for preparing a palladium acetate trimer. Background Art
[0002] Currently, CO 2 Widely used in various chemical conversions, using CO 2 The synthesis of carboxylic acid compounds as raw materials is the most eye-catching because carboxylic acids are a very important class of compounds, the basic structural units of many biologically active natural products and drug molecules, important intermediates in organic synthesis, and important raw materials for fine chemicals.
[0003] Palladium acetate trimer is a red-yellow crystal or brown powder, which is easily soluble in organic reagents but insoluble in water. It is one of the most commonly used precursors in palladium catalyst organic synthesis. It has an unusual D 3h The structure is six acetate groups bridging three nearly equilateral triangular planar metal Pd atoms. Therefore, a large number of catalysts for cross-coupling reactions, olefin aromatization reactions, olefin carbonylation reactions, etc. can be synthesized. It is widely used in the electronics industry, medicine and bioengineering fields. It is a conventional precursor that can induce or catalyze various organic synthesis reactions.
[0004] The traditional method of using palladium black as a palladium source to prepare palladium acetate requires the use of nitric acid or glacial acetic acid, which introduces nitrogen atoms or chlorine atoms and inevitably generates a by-product Pd 3 (OAc) 5 (NO 2 ) and insoluble polymer [Pd(OAc) 2 ]n, these by-products often lead to catalyst deactivation in harsh reaction conditions, seriously affecting product quality and purity, making it impossible to efficiently promote the reaction and difficult to meet high-standard industrial needs or scientific research requirements. In addition, the palladium acetate mixture prepared by mixing colloidal palladium with acetic acid and hydrochloric acid is cumbersome in process and uses a large amount of expensive raw materials and auxiliary materials, which greatly increases the production cost and is not conducive to large-scale production. Therefore, it is necessary to find a low-cost palladium source that can effectively avoid the generation of by-products, is convenient for separation and purification, and is environmentally friendly to prepare a high-purity palladium acetate trimer. Summary of the invention
[0005] In view of the above technical problems, the present invention provides a method for preparing a palladium acetate trimer. The method comprises reacting sponge palladium with an appropriate amount of methyl iodide to react with CO at low temperature. 2 The reaction can simply and quickly obtain high-purity, high-yield, universal palladium acetate trimer, thereby improving the activity of the catalyst.
[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing palladium acetate trimer, wherein sponge palladium and solid iodine are added to an ether reagent, iodomethane is added, and the mixture is stirred at -80°C to -5°C to obtain a suspension, and then CO is introduced. 2 The solution is heated until it is saturated, washed, and filtered to obtain a filtrate and a filter residue, and the filter residue is dried to obtain palladium acetate trimer A. The filtrate is rotary evaporated, washed, and dried to obtain palladium acetate trimer B. The palladium acetate trimer A and the palladium acetate trimer B are mixed to obtain palladium acetate trimer.
[0007] The reaction process is as follows:
[0008]
[0009] As a preferred embodiment of the present invention, the ether reagent is at least one of anhydrous ether and ultra-dry tetrahydrofuran, the mass of solid iodine is 0.1‰ to 3‰ of the mass of the ether reagent, and the mass ratio of sponge palladium to ether reagent is 1:(10 to 15).
[0010] As a preferred embodiment of the present invention, iodomethane is added to the ether reagent in a dropwise manner until the solid in the ether reagent is dissolved; the dropping speed is 1 to 2 drops per second.
[0011] As a preferred embodiment of the present invention, after adding iodomethane, the reaction temperature is 30-50°C and the reaction time is 1-4h.
[0012] As a preferred embodiment of the present invention, the entire reaction of the palladium acetate trimer preparation method is carried out in CO 2 atmosphere, CO must be introduced before the reaction 2 To exhaust the air in the reactor, ensure that the reaction environment is free of water and oxygen, and provide sufficient CO for subsequent reactions. 2 .
[0013] As a preferred embodiment of the present invention, the CO 2 There are two ways to introduce CO into the suspension: one is to introduce CO into the bottom of the suspension in the form of bubbling. 2 The other method is to add 0.8 to 1.2 volume equivalents of dry ice to the suspension and stir it thoroughly. 2 , and creates a low-temperature reaction environment.
[0014] As a preferred embodiment of the present invention, CO is introduced 2 If the crystals precipitate slowly or less, CO can be added slowly above the suspension. 2 The gas is removed until solid is precipitated to increase the pressure of the reaction system to improve the crystal yield.
[0015] As a preferred embodiment of the present invention, the introduction of CO2 The heating temperature after the solution is saturated is 35°C to 45°C.
[0016] As a preferred embodiment of the present invention, a gas-liquid collecting device is installed on the top of the reactor to collect CO before heating. 2 , collect ether or tetrahydrofuran after heating and reuse.
[0017] As a preferred embodiment of the present invention, 1 mol / L acetic acid is added to the filtrate and the pH is adjusted to 2 to 3. Adjusting the pH of the filtrate is beneficial to increasing the yield of palladium acetate trimer, which is about 3% higher than that of the product without pH adjustment.
[0018] Compared with the prior art, the present invention has the following beneficial effects:
[0019] (1) The present invention utilizes a palladium precursor sponge palladium with good stability to efficiently prepare a high-purity palladium acetate trimer, and improves the product yield and purity.
[0020] (2) The synthesis process of this method is simple and intuitive, and no nitrogen or chlorine atoms are introduced during the preparation process, and high-purity palladium acetate trimer can be obtained. 3 (OAc) 5 (NO 2 ) and insoluble polymer [Pd(OAc) 2 ] n Technical problems of by-products. In addition, compared with the traditional preparation method, the preparation method of palladium acetate trimer of the invention is faster and more convenient, and effectively shortens the time required for product preparation.
[0021] (3) The present invention utilizes CO 2 As raw materials, it can reduce greenhouse gas emissions in the atmosphere and is beneficial to environmental protection; the used CO 2 , ether or tetrahydrofuran are easy to collect and can be reused, which greatly reduces the production cost. DETAILED DESCRIPTION
[0022] To better illustrate the purpose, technical scheme and advantages of the present invention, the technical scheme and effect of the present invention are further described below by multiple exemplary embodiments, and this detailed description should not be considered as limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention. The following examples are exemplary and are intended to be used to explain the present invention, and should not be understood as limitation of the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper limit and the lower limit of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.
[0023] Example 1
[0024] A method for preparing a palladium acetate trimer comprises the following steps:
[0025] Take 100g of sponge palladium and 0.14g of solid iodine and immerse them in 140g of anhydrous ether. Then pass CO into the 2 The air in the reactor was exhausted, heated to 45°C, and methyl iodide was slowly added at a rate of 2 drops per second until the solid disappeared. After reacting for 4 hours, the reactor was stirred at -70°C for 24 hours to obtain a suspension of the intermediate palladium CH 3 Pd II I. Bubble CO into the bottom of the suspension 2 The mixture was heated at 40°C until crystals were precipitated to obtain a reddish brown solid block, which was ultrasonically washed with clean water, filtered, and dried to obtain 168.07 g of reddish yellow crystalline palladium acetate trimer; the filtered filtrate was subjected to rotary evaporation, washed with clean water, and dried to obtain 18.52 g of brown powdered palladium acetate trimer. A total of 189.59 g of the product was obtained, with a yield of 89.19% and a purity of 98.85%. The palladium content was 47.8% as determined by ICP.
[0026] Example 2
[0027] A method for preparing a palladium acetate trimer comprises the following steps:
[0028] Take 100g of sponge palladium and 0.15g of solid iodine and immerse them in 150g of anhydrous ether. Then pass CO 2 The air in the reactor was exhausted, heated to 50°C, and methyl iodide was slowly added at a rate of 1 drop per second until the solid disappeared. After reacting for 4 hours, the reactor was stirred at -30°C for 24 hours to obtain a suspension of the intermediate palladium CH 3 Pd III. Add 0.9 volume equivalent of dry ice until crystals precipitate, heat at 45°C to obtain a reddish brown block solid, wash with clean water ultrasonically, filter, and dry to obtain 167.34 g of reddish yellow crystalline palladium acetate trimer; perform rotary evaporation on the filtered filtrate, wash with clean water, and dry to obtain 18.66 g of brown powdered palladium acetate trimer. A total of 186.00 g of the product was obtained, with a yield of 89.09% and a purity of 98.97%. The palladium content was 47.9% as determined by ICP.
[0029] Example 3
[0030] A method for preparing a palladium acetate trimer comprises the following steps:
[0031] Take 100g of sponge palladium and 0.1g of solid iodine and immerse them in 100g of ultra-dry tetrahydrofuran. Then pass CO into the mixture. 2 The air in the reactor was exhausted, heated to 35°C, and methyl iodide was slowly added at a rate of 2 drops per second until the solid disappeared. After reacting for 4 hours, the reactor was stirred at -5°C for 24 hours to obtain a suspension of the intermediate palladium CH 3 Pd II I. Bubble CO into the bottom of the suspension 2 The mixture was heated at 45°C until crystals precipitated, and a reddish-brown solid block was obtained. The solid was ultrasonically washed with clean water, filtered, and dried to obtain 153.19 g of a reddish-yellow crystalline palladium acetate trimer. The filtered filtrate was rotary evaporated, washed with clean water, and dried to obtain 26.82 g of a brown powdery palladium acetate trimer. A total of 180.01 g of the product was obtained, with a yield of 86.22% and a purity of 98.92%. The palladium content was 47.9% as determined by ICP.
[0032] Example 4
[0033] A method for preparing a palladium acetate trimer comprises the following steps:
[0034] Take 100g of sponge palladium and 0.1g of solid iodine and immerse them in 100g of ultra-dry tetrahydrofuran. Then pass CO into the mixture. 2 The air in the reactor was exhausted, heated to 35°C, and methyl iodide was slowly added at a rate of 1 drop per second until the solid disappeared. After reacting for 4 hours, the reactor was stirred at -25°C for 24 hours to obtain a suspension of the intermediate palladium CH 3 Pd II I. Add 0.8 volume equivalent of dry ice until crystals precipitate, heat at 35°C to obtain a reddish brown block solid, wash with clean water ultrasonically, filter, and dry to obtain 141.34 g of reddish yellow crystalline palladium acetate trimer; perform rotary evaporation on the filtered filtrate, wash with clean water, and dry to obtain 49.61 g of brown powdered palladium acetate trimer, and obtain a total of 190.95 g of the product, with a yield of 91.08% and a purity of 98.79%. The palladium content is 47.7% as determined by ICP.
[0035] Example 5
[0036] A method for preparing a palladium acetate trimer comprises the following steps:
[0037] Take 100g of sponge palladium and 0.14g of solid iodine and immerse them in 140g of anhydrous ether. Then pass CO into the 2 The air in the reactor was exhausted, heated to 45°C, and methyl iodide was slowly added at a rate of 2 drops per second until the solid disappeared. After reacting for 4 hours, the reactor was stirred at -70°C for 24 hours to obtain a suspension of the intermediate palladium CH 3 Pd II I. Bubble CO into the bottom of the suspension 2 When crystals precipitate, add CO above the suspension. 2 To 0.5MPa, heated at 35°C to obtain a reddish brown block solid, washed with clean water ultrasonically, filtered, and dried to obtain 171.23g of reddish yellow crystalline palladium acetate trimer; the filtered filtrate was subjected to rotary evaporation, washed with clean water, and dried to obtain 9.83g of brown powdered palladium acetate trimer. A total of 181.06g of the product was obtained, with a yield of 86.55%, a purity of 98.83%, and a palladium content of 47.8% as determined by ICP.
[0038] Example 6
[0039] A method for preparing a palladium acetate trimer comprises the following steps:
[0040] Take 100g of sponge palladium and 0.15g of solid iodine and immerse them in 150g of anhydrous ether. Then pass CO 2 The air in the reactor was exhausted, heated to 45°C, and methyl iodide was slowly added at a rate of 2 drops per second until the solid disappeared. After reacting for 4 hours, the reactor was stirred at -10°C for 24 hours to obtain a suspension of the intermediate palladium CH 3 Pd II I. Bubble CO into the bottom of the suspension 2 The mixture was heated at 45°C until crystals precipitated, and a reddish-brown solid block was obtained. The solid was ultrasonically washed with clean water, filtered, and dried to obtain 162.07 g of a reddish-yellow crystalline palladium acetate trimer. 1 mol / L acetic acid was added to the filtrate to adjust the pH to 3, and then rotary evaporated. The solid was washed with clean water and dried to obtain 25.60 g of a brown powdery palladium acetate trimer. A total of 187.67 g of the product was obtained, with a yield of 89.89% and a purity of 98.93%. The palladium content was 47.9% as determined by ICP.
Claims
1. A method for preparing a palladium acetate trimer, characterized in that: In a carbon dioxide atmosphere, sponge palladium and solid iodine are added to an ether reagent, iodomethane is added to react, and then stirred at -80°C to -5°C to obtain a suspension, CO2 is introduced into the suspension until saturated, and then heated, washed and filtered to obtain a filtrate and a filter residue, the filter residue is dried to obtain palladium acetate trimer A, the filtrate is rotary evaporated, washed and dried to obtain palladium acetate trimer B, and palladium acetate trimer A and palladium acetate trimer B are mixed to obtain palladium acetate trimer.
2. The method for preparing a palladium acetate trimer according to claim 1, wherein: The ether reagent is at least one of anhydrous ether and super dry tetrahydrofuran.
3. The method for preparing the palladium acetate trimer according to claim 1, wherein: The mass ratio of the sponge palladium to the ether reagent is 1:(10-15).
4. The method for preparing the palladium acetate trimer according to claim 1, wherein: Add iodomethane to the ether reagent in a dropwise manner until the solid in the ether reagent is dissolved; the dropping speed is 1 to 2 drops per second.
5. The method for preparing the palladium acetate trimer according to claim 1, wherein: The mass of solid iodine is 0.1‰ to 3‰ of the mass of the ether reagent.
6. The method for preparing the palladium acetate trimer according to claim 1, wherein: After adding iodomethane, the reaction temperature is 30-50°C and the reaction time is 1-4h.
7. The method for preparing the palladium acetate trimer according to claim 1, wherein: The heating temperature is 35°C to 45°C.
8. The method for preparing the palladium acetate trimer according to claim 1, wherein: There are two ways to introduce CO2 into the suspension: one is to introduce CO2 at the bottom of the suspension in the form of bubbling; the other is to add 0.8 to 1.2 volume equivalents of dry ice into the suspension.
9. The method for preparing the palladium acetate trimer according to claim 1, wherein: Acetic acid was added to the filtrate to adjust the pH to 2-3.