Platinum catalyst for hydrosilylation and preparation method thereof

Abstract

The invention discloses a platinum catalyst for hydrosilylation and a preparation method thereof, and the preparation method comprises the following steps: (1) mixing a platinum metal precursor and a low cosolvent, and fully stirring and dissolving; (2) under the protection of nitrogen, adding isopropanol, fully stirring, gradually dropwise adding vinyl double-end socket, and continuously stirring for 30-90 minutes; and (3) under the protection of nitrogen, heating to 60-150 DEG C, adding a basic catalyst, continuously stirring to react for 30-90 minutes, cooling, washing, and carrying out reduced pressure distillation to obtain the platinum catalyst. The low cosolvent is added during synthesis of the platinum catalyst, so that the electronic effect and coordination environment of the platinum catalyst are regulated and controlled, and the stability of the catalyst is improved. The method is simple in preparation process, and the catalyst has high catalytic activity and selectivity in olefin catalytic addition reaction.

Description

Technical Field

[0001] The invention relates to a catalyst, in particular to a platinum catalyst for hydrosilylation reaction and a preparation method thereof. Background Art

[0002] The hydrosilylation reaction is one of the most important synthetic pathways for functional organosilicon compounds, and it plays an important role in organosilicon chemistry and the organosilicon industry. Transition metals are often used as catalysts in the hydrosilylation reaction, among which platinum complexes are the most active and widely used. The activity of platinum catalysts largely determines the production capacity of organosilicon materials and has a profound impact on industrial applications. At present, the platinum catalysts used in industry are mainly Speier catalysts and Karstedt catalysts.

[0003] The two types of platinum catalysts commonly used in the market are homogeneous catalysts with high reactivity, but they are unstable during the reaction and may generate metallic platinum or insoluble colloids in the reaction medium, resulting in a shorter service life. In addition, this type of catalyst produces by-products in the hydrosilylation reaction, resulting in poor activity selectivity.

[0004] CN114700116B obtains a dendritic addition catalyst by co-hydrolyzing a trialkoxysilylpropylpolyethylene glycol monoether and an organic phosphine ligand containing a trialkoxysilyl group and then reacting with a transition metal acetate. The catalyst synthesis method is complicated, and the organic phosphine ligand has certain toxicity, which limits the application of the catalyst.

[0005] CN111250169A synthesizes a coated microcapsule platinum complex catalyst to extend the use and storage time of the platinum catalyst at room temperature and prolong the curing time. However, the catalyst has low activity and a complicated preparation process, making it difficult to achieve large-scale industrial application.

[0006] Therefore, there is an urgent need for an improved method for preparing platinum catalysts to improve the stability of the catalysts and ensure the activity and selectivity of the catalysts in the hydrosilylation reaction. Summary of the invention

[0007] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a platinum catalyst for hydrosilylation reaction and a preparation method thereof. The method adds a low co-solvent to the synthetic platinum catalyst to regulate the electronic effect of the platinum catalyst and improve the stability of the catalyst; the hydrogen bonds in the low co-solvent are also conducive to improving the catalytic activity in hydrosilylation.

[0008] To achieve the above object, the technical solution of the present invention is:

[0009] A method for preparing a platinum catalyst for hydrosilylation reaction comprises the following steps:

[0010] After mixing the platinum metal precursor and the low co-solvent, stir them thoroughly to dissolve;

[0011] Under nitrogen protection, add isopropanol, stir thoroughly, and gradually add vinyl double-capped tube dropwise, and continue stirring for 30 to 90 minutes;

[0012] Under nitrogen protection, the temperature is raised to 60-90°C, an alkaline catalyst is added, the reaction is stirred for 30-90 minutes, and then the temperature is lowered and cooled. The mixture is washed with isopropanol, the filtrate and the washing liquid are combined, and the volatile solvent is removed by vacuum distillation, and then toluene is added to dilute the mixture to obtain a platinum catalyst.

[0013] Wherein, the low co-solvent in step (1) is prepared from choline chloride and an organic ligand.

[0014] The organic ligand in step (1) is one of ethylene glycol, glycerol, diethylene glycol, triethylene glycol, oxalic acid, malonic acid, lactic acid, citric acid and urea. The molar ratio of choline chloride to the organic ligand is 1:(0.8-3).

[0015] The platinum metal precursor is one of chloroplatinic acid, platinum acetylacetonate, platinum nitrate and platinum chloride.

[0016] The mass ratio of the low co-solvent to the platinum precursor in the step (1) is 1:0.05-0.1.

[0017] The mass ratio of the platinum precursor to isopropanol in the step (2) is 1:10-50.

[0018] The mass ratio of the platinum precursor to the vinyl double head in the step (2) is 1:10-20.

[0019] The alkaline catalyst in step (3) is one of sodium bicarbonate, sodium hydroxide, potassium bicarbonate, potassium hydroxide and diammonium bicarbonate; the mass ratio of the platinum precursor to the alkaline catalyst is 1:0.5-5.

[0020] Compared with the prior art, the present invention has the following beneficial effects: the synthesis process of the present invention is simple, and the platinum catalyst is synthesized by dissolving the platinum precursor in a low co-solvent. The organic ligand in the low co-solvent is complexed with the platinum cation center through the coordinating atom, so that the charge of the platinum cation is delocalized, the charge density is reduced, and the Coulomb force between the anion and the cation is reduced. The electron-guiding effect of the low co-solvent improves the stability of the platinum catalyst, and a large amount of hydrogen bonds in the solvent are conducive to improving the catalytic activity in the hydrosilylation. DETAILED DESCRIPTION

[0021] The present invention is illustrated by the following examples, but is not limited to the following examples. Without departing from the scope of the preceding and following descriptions, various modifications are included within the technical scope of the present invention.

[0022] Embodiment 1:

[0023] Use a three-necked flask to add 5g of choline chloride and 4.7g of ethylene glycol in sequence, and stir at 60°C until they become a colorless transparent liquid to form a low co-solvent; add 0.5g of chloroplatinic acid, stir thoroughly and dissolve completely;

[0024] After nitrogen protection, add 25 g of isopropanol, stir thoroughly, then add 8 g of vinyl double-capped end cap, and continue stirring for 60 min;

[0025] Under nitrogen protection, the temperature was raised to 110°C, 1 g of sodium bicarbonate was added, stirring was continued for 60 minutes, and then the temperature was lowered and cooled. The mixture was washed with isopropanol, and the filtrate and washings were combined, and the volatile solvent was removed by vacuum distillation, and then toluene was added to dilute the mixture to obtain a platinum catalyst.

[0026] Embodiment 2:

[0027] Use a three-necked flask to add 5g of choline chloride and 4.0g of oxalic acid in sequence, and stir at 80°C until a colorless transparent liquid is formed to form a low co-solvent; add 0.8g of chloroplatinic acid, stir thoroughly and dissolve completely;

[0028] After nitrogen protection, add 30 g of isopropanol, stir thoroughly, then add 10 g of vinyl double-capped end cap, and continue stirring for 60 min;

[0029] Under nitrogen protection, the temperature was raised to 110°C, 0.5 g of sodium bicarbonate was added, stirring was continued for 60 min, and then the temperature was lowered and cooled. The mixture was washed with isopropanol, and the filtrate and washings were combined, and the volatile solvent was removed by vacuum distillation, and then toluene was added to dilute the mixture to obtain a platinum catalyst.

[0030] Embodiment 3:

[0031] Use a three-necked flask to add 5g of choline chloride and 8.6g of citric acid in sequence, and stir at 80°C until a colorless transparent liquid is formed to form a low co-solvent; add 1g of chloroplatinic acid, stir thoroughly and dissolve completely;

[0032] After nitrogen protection, add 30 g of isopropanol, stir thoroughly, then add 10 g of vinyl double-capped end cap, and continue stirring for 60 min;

[0033] Under nitrogen protection, the temperature was raised to 120°C, 1 g of sodium bicarbonate was added, stirring was continued for 60 min, and then the temperature was lowered and cooled. The mixture was washed with isopropanol, and the filtrate and washings were combined, and the volatile solvent was removed by vacuum distillation, and then toluene was added to dilute the mixture to obtain a platinum catalyst.

[0034] Embodiment 4:

[0035] Use a three-necked flask to add 5g of choline chloride and 6.8g of propylene glycol in sequence, and stir at 80°C until they become a colorless transparent liquid to form a low co-solvent; add 0.5g of chloroplatinic acid, stir thoroughly and dissolve completely;

[0036] After nitrogen protection, add 25 g of isopropanol, stir thoroughly, then add 8 g of vinyl double-capped end cap, and continue stirring for 60 min;

[0037] Under nitrogen protection, the temperature was raised to 120°C, 1 g of sodium hydroxide was added, stirring was continued for 60 minutes, and then the temperature was lowered and cooled. The mixture was washed with isopropanol, and the filtrate and washings were combined, and the volatile solvent was removed by vacuum distillation, and then toluene was added to dilute the mixture to obtain a platinum catalyst.

[0038] Embodiment 5:

[0039] Use a three-necked flask to add 5g of choline chloride and 5.2g of urea in sequence, and stir at 60°C until a colorless transparent liquid is formed to form a low co-solvent; add 0.5g of chloroplatinic acid, stir thoroughly and dissolve completely;

[0040] After nitrogen protection, add 25 g of isopropanol, stir thoroughly, then add 8 g of vinyl double-capped end cap, and continue stirring for 60 min;

[0041] Under nitrogen protection, the temperature was raised to 120°C, 1 g of sodium bicarbonate was added, stirring was continued for 60 min, and then the temperature was lowered and cooled. The mixture was washed with isopropanol, and the filtrate and washings were combined, and the volatile solvent was removed by vacuum distillation, and then toluene was added to dilute the mixture to obtain a platinum catalyst.

[0042] Embodiment 6:

[0043] Use a three-necked flask to add 5g of choline chloride and 6.3g of diethylene glycol in sequence, and stir at 80°C until a colorless transparent liquid is formed to form a low co-solvent; add 1.1g of chloroplatinic acid, stir thoroughly and dissolve completely;

[0044] After nitrogen protection, add 30 g of isopropanol, stir thoroughly, then add 8 g of vinyl double-capped end cap, and continue stirring for 60 min;

[0045] Under nitrogen protection, the temperature was raised to 120°C, 1 g of sodium bicarbonate was added, stirring was continued for 60 min, and then the temperature was lowered and cooled. The mixture was washed with isopropanol, and the filtrate and washings were combined, and the volatile solvent was removed by vacuum distillation, and then toluene was added to dilute the mixture to obtain a platinum catalyst.

[0046] Comparative Example 1:

[0047] Under nitrogen protection, add 1.0g chloroplatinic acid and 30g isopropanol in a three-necked flask in sequence, stir and dissolve thoroughly, then add 8g ethylene double-capped, and continue stirring for 60min;

[0048] The temperature was raised to 120°C under nitrogen protection, 1 g of sodium bicarbonate was added, stirring was continued for 60 min, and then the temperature was lowered and cooled. The mixture was washed with isopropanol, and the filtrate and washings were combined, and the volatile solvent was removed by vacuum distillation, and then toluene was added to dilute the mixture to obtain a platinum catalyst.

[0049] The catalyst of the above example and 1-octene (1.5 mol) were respectively taken into a three-necked flask, and the temperature was slowly raised to 80° C. under nitrogen protection. After stirring for 30 min, triethoxysilane (1.75 mol) was added dropwise, and the reaction temperature was maintained. After the reaction was continued for 6 h, it was cooled to room temperature, and the catalyst was settled. The upper liquid was measured for 1-octene conversion by GC-Ms, and the upper liquid was distilled under reduced pressure to collect the yield of the addition product. The reaction results are shown in Table 1.

[0050] Table 1 Performance evaluation results of various examples and comparative examples on 1-octene hydrosilylation reaction

[0051] Catalyst dosage 1-Octene conversion Product yield Example 1 5ppm 95.8％ 94.5％ Example 2 5ppm 96.8％ 95.6％ Example 3 5ppm 99.4％ 98.2％ Example 4 5ppm 96.2％ 95.4％ Example 5 5ppm 97.3％ 96.1％ Example 6 5ppm 95.5％ 94.4％ Comparative Example 1 5ppm 90.2％ 89.5％

Claims

1. A platinum catalyst for hydrosilylation reaction and a preparation method thereof, characterized in that: The steps include: After mixing the platinum metal precursor and the low co-solvent, stir them thoroughly to dissolve; Under nitrogen protection, add isopropanol, stir thoroughly, and gradually add vinyl double-capped tube dropwise, and continue stirring for 30 to 90 minutes; Under nitrogen protection, after heating to 60-150°C, add alkaline catalyst and continue stirring to react for 30-90 minutes, then cool down; Washing with isopropanol, combining the filtrate and the washings, removing the volatile solvent by distillation under reduced pressure, and then adding toluene to dilute to obtain a platinum catalyst; Wherein, the low co-solvent in step (1) is made of choline chloride and an organic ligand.

2. The preparation method according to claim 1, characterized in that The organic ligand described in step (1) is one of ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, oxalic acid, malonic acid, lactic acid, citric acid, and urea; wherein the molar ratio of choline chloride to the organic ligand is 1:0.8-3.

3. The preparation method according to claim 1, characterized in that The platinum metal precursor described in step (1) is one of chloroplatinic acid, platinum acetylacetonate, platinum nitrate and platinum chloride.

4. The preparation method according to claim 1, characterized in that The mass ratio of the low co-solvent to the platinum precursor described in step (1) is 0.05 to 1.2:

1.

5. The preparation method according to claim 1, characterized in that The mass ratio of the platinum precursor to isopropanol in step (2) is 1:10-50.

6. The preparation method according to claim 1, characterized in that The mass ratio of the platinum precursor to the vinyl double head described in step (2) is 1:10-20.

7. The preparation method according to claim 1, characterized in that The alkaline catalyst described in step (3) is one of sodium bicarbonate, sodium hydroxide, potassium bicarbonate, potassium hydroxide, and diammonium bicarbonate; the molar ratio of the platinum precursor to the alkaline catalyst is 1:1-5.