CN112552502B - Preparation method of catalyst for perfluoropolyether polymerization - Google Patents

Abstract

The invention belongs to the technical field of perfluoropolyether polymerization, and in particular relates to a method for preparing a catalyst for perfluoropolyether polymerization, comprising the following steps: (1) combining Ni(cod) ₂ with PQ ₃ (Q=Me , Et, ⁱ Pr) are mixed and reacted in a solvent to prepare raw material B; (2) after obtaining raw material B, the activation reaction of C-F bond is carried out with raw material B and raw material A in a solvent to obtain a perfluoropolyether for perfluoropolyether Catalyst for polymerization. The present invention prepares organometallic complexes containing metal fluorine bonds by screening specific ligands, and applies the complexes as catalysts to K-type perfluoropolyether polymerization. Compared with traditional inorganic fluorides, in a small amount of In the case of a catalyst, the polymerization degree of the perfluoropolyether oil can be significantly improved, and the amount of solvent used can be reduced, thereby effectively reducing the cost of the polymerization reaction. At the same time, the preparation method of the present invention has simple steps, no harsh conditions, and high yield of the target product. .

Description

Preparation method of catalyst for perfluoropolyether polymerization

technical field

The invention belongs to the technical field of perfluoropolyether polymerization, and in particular relates to a preparation method of a catalyst for perfluoropolyether polymerization.

Background technique

Perfluoropolyether (PFPE, English name PerfluoroPolyethers) is a kind of high molecular polymer, which is colorless, odorless and transparent oily liquid at room temperature. Because perfluoropolyether has the characteristics of heat resistance, oxidation resistance, radiation resistance, corrosion resistance and non-flammability, it has become an extremely reliable lubricant under harsh conditions. Since the 1960s, researchers at home and abroad have carried out extensive research on perfluoropolyether, and now perfluoropolyether is widely used in chemical, electronic, electrical, mechanical, nuclear, aerospace and other fields.

Compared with hydrocarbon lubricants, PFPE lubricants are basically similar in molecular structure, but fluorine atoms replace hydrogen atoms in the molecules, thus replacing the C-H bonds in hydrocarbons with stronger C-F bonds, and C-O and C-C strong covalent bonds The existence of PFPE and the molecular neutrality of PFPE make PFPE have high thermal and oxidative stability, as well as good chemical inertness and insulating properties. The higher molecular weight PFPE also has low volatility, a wider liquid temperature range, and excellent viscosity-temperature characteristics. Compared with chlorofluorocarbon lubricants, perfluoropolyether lubricants have a wider operating temperature range, and not only avoid the shortcomings of chlorofluorocarbons that are easy to evaporate at high temperatures and become viscous and thicker at low temperatures, but also avoid the Chlorofluorocarbons have the disadvantage that the bearing will corrode when the lubricant is pressurized in the use of high-load bearings. Compared with fluorosilicone lubricants, although the viscosity and evaporation rate of perfluoropolyether lubricants are comparable to those of fluorosilicone lubricants, their lubricating effect and chemical stability are much better than those of fluorosilicone lubricants. In addition, the main physical and chemical properties of polymers include: shear stability, biological inertness, low surface energy, good lubricity, and compatibility with plastics, metals, and elastomers. PFPE has a good combination of properties, making it an extremely reliable lubricant in harsh environments.

The molecular structure of K-type perfluoropolyether is as follows:

Among them, the K-type perfluoropolyether has the structure shown above. It was first invented by 3M Company in the 1960s. After more than 50 years of development, a series of perfluoropolyether oil grades have been formed in different fields; Systematic research, especially a series of screening of catalysts, species and systems. L. Heinrich et al. used AgNO ₃ as a catalyst to make oligomers of HFPO in acetonitrile, in which the yield of dimer was 86% and the yield of trimer was 3%. However, due to the photosensitivity of AgNO ₃ , it is easy to generate nitrous acid, so this method has certain limitations. Germany GK uhne used CuCl/CuC1 ₂ /acrylonitrile catalytic system to oligomerize HFPO in acetonitrile solvent, and the yield of dimer can reach 82%. However, acrylonitrile in this method is suspected of causing cancer. Japanese YOSHIDA.AKIRA et al. used CsF as a catalyst to prepare HFPO polymer in a protic solvent, and the reaction temperature was kept at -20°C. However, the water absorption of cesium fluoride makes the experimental operation difficult, and its price is expensive, which is not suitable for industrial application. T.Martini used bis-dialkylaminodifluoromethane as catalyst and diglyme as solvent to carry out oligomerization of HFPO. The yields of trimer and tetramer in the final product were 59% and 45%, respectively. %. Alfrid et al. used a catalyst system to achieve the oligomerization of HFPO. The system consists of a mixture of alkali metal fluorides, dinitrile compounds and polyglymes. When the concentration of polyether in the catalyst system is large, it will lead to an increase in the average degree of polymerization and reaction rate, so it is possible to consciously use a lower concentration of polyether to obtain a polymer with trimer as the main component, and use a higher concentration of polyether. The ether obtains a polymer in which the tetramer is the main component. This catalyst system can simultaneously achieve a narrow molecular weight distribution. Duan Youlu, Ni Danan and others studied the self-polymerization of perfluoropropylene oxide and the bifunctional anionic polymerization of perfluoropentane (or hexamethylene) diacyl fluoride catalyzed by KF. It is found that the self-polymerization activity of KF perfluoropropylene oxide under normal pressure is much lower than the catalytic activity of CsF reported in the literature, the conversion rate of the reaction is low, and the molecular weight of the generated perfluoropolyether acyl fluoride is small, generally only dimer. . Klaus.Hintzer et al. also used KF as a catalyst. Under a certain pressure and temperature, a mixed gas ( The mass ratio of substances is 4 to 0.05), and the polymerization is carried out.

According to the K-type perfluoropolyether obtained by the polymerization method mentioned in the above-mentioned document, most of the catalysts used are alkali metal fluoride salt potassium fluoride and cesium fluoride, and the solvent used is a polar aprotic solvent , the solubility of alkali metal fluoride salts in solvents is very poor, which results in the need to use a large amount of solvent to dissolve the catalyst, resulting in increased polymerization costs and difficulty in solvent recovery. In addition, the catalytic activity of potassium fluoride is low, and perfluoropolyether with high degree of polymerization cannot be obtained. For cesium fluoride, although the catalytic activity is higher than that of potassium fluoride, it is expensive and has the characteristics of strong hygroscopicity. Difficulties in industrial scale-up.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is: to overcome the deficiencies of the prior art, to improve the shortcoming of the low solubility of the current inorganic type catalyst in organic solvents, and to provide a preparation method of a catalyst for perfluoropolyether polymerization, The obtained metal nickel complex is used as a catalyst in the polymerization of K-type perfluoropolyether. Compared with traditional inorganic catalysts, the polymerization degree of perfluoropolyether can be significantly improved under the same dosage. In addition, It also has good effects in improving yield and reducing the amount of solvent used, thereby further reducing the production cost of K-type perfluoropolyether.

The preparation method of the catalyst for perfluoropolyether polymerization according to the present invention comprises the following steps:

(1) Under the protection of inert gas, Ni(cod) ₂ and PQ ₃ (Q=Me, Et, ⁱ Pr) are mixed and reacted in a solvent to prepare raw material B;

(2) after the raw material B is obtained, the activation reaction of the C-F bond is carried out with the raw material B in a solvent to obtain a catalyst for the perfluoropolyether polymerization reaction;

in:

The structural formula (II) of raw material B is selected from:

Ni(PMe ₃ ) ₄ (II-1)

Ni(PEt ₃ ) ₄ (II-2)

Ni(P ⁱ Pr ₃ ) ₄ (II-1)

The structural formula (I) of raw material A is:

The structural formula (III) of the catalyst is:

(III): R=PMe ₃ , PEt ₃ , P ⁱ Pr ₃ .

The structural formula (III) of the catalyst is selected from:

in:

The solvent described in step (1) and step (2) is an aprotic solvent, preferably THF (tetrahydrofuran), more preferably dehydrated anhydrous THF, which can enhance the solubility of the catalyst. The inert gas is preferably high-purity nitrogen.

The molar ratio of Ni(cod) ₂ to PQ ₃ in step (1) is 12-15:25-32, preferably 13.5:28.4.

The mixing temperature in step (1) is 20°C to 80°C, preferably 45 or 60°C, and the mixing reaction time is 4 to 10 hours, preferably 6 hours.

The ratio of the total amount of Ni(cod) ₂ and PQ ₃ in the step (1) to the amount of the solvent is 71-90 mmol: 50-100 mL, preferably 84.6 mmol: 100 mL.

After Ni(cod) ₂ reacts with PQ ₃ (Q=Me, Et, ⁱ Pr) in step (1), the reaction product solution is cooled, and the cooled product solution temperature is room temperature, and the cooled solution will There is a precipitate, the obtained precipitate is suction filtered, then the precipitated solid is extracted with n-pentane, and then the extract is recrystallized to obtain raw material B.

The activation reaction process described in the step (2) is as follows: the raw material B and the raw material A obtained in the step (1) are driven into the solvent by a syringe under the condition of a protective gas, and the C-F bond activation reaction is carried out to obtain the whole process. Catalyst for fluoropolyether polymerization.

In step (2), the molar ratio of raw material B and raw material A is 8-9:10-12, preferably 8.4:11.2.

The ratio of the total amount of the raw material B and the raw material A described in the step (2) to the amount of the solvent is 40-60 mmol: 10-60 mL, preferably 49.06 mmol: 60 mL.

The reaction temperature in step (2) is 25°C to 40°C, preferably 40°C, and the reaction time is 6h to 12h, preferably 8h.

In the step (2), the precipitation in the obtained reactant is suction filtered, and then n-pentane is used to wash the precipitated solid, and after the washed solid is dried, the nickel metal complex having the structure shown in formula (III) is obtained, using Catalyst for perfluoropolyether polymerization. The present invention has no particular limitation on the steps of suction filtration and recrystallization, and the steps of suction filtration, n-pentane and drying well known to those skilled in the art can be used.

Compared with the prior art, the beneficial effects of the present invention are as follows:

The present invention prepares organometallic complexes containing metal fluorine bonds by screening specific ligands, and applies the complexes as catalysts to K-type perfluoropolyether polymerization. Compared with traditional inorganic fluorides, in a small amount of In the case of a catalyst, the polymerization degree of the perfluoropolyether oil can be significantly improved, and the amount of solvent used can be reduced, thereby effectively reducing the cost of the polymerization reaction. For the catalytic polymerization of K-type perfluoropolyether, the present invention has Compared with salt, under the condition of reaching the same degree of polymerization, the amount of catalyst is significantly reduced. At the same time, the preparation method of the invention has simple steps, no harsh condition requirements, and high yield of the target product.

Detailed ways

The present invention will be further described below in conjunction with the embodiments.

All raw materials used in the examples are commercially available unless otherwise specified.

Example 1

The structural formula (I) of raw material A is:

Raw material B has the structure shown in formula (II-1), Ni(PMe ₃ ) ₄ ;

The catalyst has the structure shown in formula (III-1):

The described preparation method of the catalyst used for perfluoropolyether polymerization comprises the following steps:

Step 1: Under nitrogen protection system, weigh the raw materials Ni(cod) ₂ (47.8mmol, 13.15g), PMe ₃ (trimethylphosphine) (100.33mmol, 7.63g), add to the reaction system, add 175mL of THF solution , reacted at 45 °C for 6 h under nitrogen protection, then cooled to room temperature, drained the solvent THF, extracted with n-pentane, and put the extract into a 0 °C refrigerator to obtain yellow needle-like crystals, which was raw material B (7.29 g, produced rate 42%).

Step 2: Weigh raw material B (15.43 mmol, 5.60 g), add raw material A (19.29 mmol, 3.26 g), then add 50 mL of THF to the system, react at 25 °C for 10 h under nitrogen protection, filter the solvent, n-pentane Wash, put the remaining solid after washing into a vacuum drying oven and dry to obtain a yellow powdery nickel metal complex for perfluoropolyether polymerization catalyst (3.40g, yield 58%), with formula (III -1) shown in the structure.

HPLC purity: 99.2%. Mass Spec: Calculated 379.90; Tested 380.04. Elemental analysis: Calculated values: C: 34.78%; H: 4.78%; N: 3.69%; tested values: C: 34.97%; H: 4.91%; N: 3.56%.

Example 2

Raw material A is the same as Example 1:

Raw material B has the structure shown in formula (II-1), Ni(PMe ₃ ) ₄ ;

The catalyst has the structure shown in formula (III-1):

The described preparation method of the catalyst used for perfluoropolyether polymerization comprises the following steps:

Step 1: Under nitrogen protection system, weigh the raw materials Ni(cod) ₂ (114.7mmol, 31.55g), PMe ₃ (246.61mmol, 18.76g), add to the reaction system, add 450mL of THF solution, 60 ℃ under nitrogen protection The reaction was performed for 5 h, then cooled to room temperature, the solvent THF was drained, extracted with n-pentane, and the extract was placed in a 0°C refrigerator to obtain yellow needle-like crystals, which was raw material B (25.81, yield 62%).

Step 2: Weigh raw material B (42.94 mmol, 15.59 g), add raw material A (53.68 mmol, 9.07 g), then add THF 120 mL to the system, under nitrogen protection, react at 25 °C for 10 h, filter the solvent, n-pentane Wash, put the remaining solid after washing into a vacuum drying oven and dry to obtain a yellow powdery nickel metal complex for the catalyst (10.44g, yield 64%) used for perfluoropolyether polymerization, with formula (III -1) shown in the structure.

HPLC purity: 98.7%. Mass Spec: Calculated 379.90; Tested 379.76. Elemental analysis: Calculated values: C: 34.78%; H: 4.78%; N: 3.69%; tested values: C: 34.61%; H: 4.69%; N: 3.82%.

Example 3

Raw material A is the same as Example 1;

Raw material B has the structure shown in formula (II-2), Ni(PEt ₃ ) ₄ ;

The catalyst has the structure shown in formula (III-2):

The described preparation method of the catalyst used for perfluoropolyether polymerization comprises the following steps:

Step 1: Under nitrogen protection system, weigh the raw materials Ni(cod) ₂ (24.8 mmol, 6.82 g), PEt ₃ (triethylphosphine) (53.29 mmol, 6.30 g), add them into the reaction system, and add 90 mL of THF solution , reacted at 45 °C for 6 h under nitrogen protection, then cooled to room temperature, drained the solvent THF, extracted with n-pentane, and put the extract into a refrigerator at 0 °C to obtain orange-red rod-shaped crystals, which was raw material B (7.51 g, produced rate 57%).

Step 2: Weigh raw material B (13.44 mmol, 7.14 g), add raw material A (16.66 mmol, 2.82 g), then add 40 mL of THF to the system, react at 30 °C for 10 h under nitrogen protection, drain the solvent, and use n-pentane Washing, drying the residue after washing in a vacuum drying oven to obtain a red nickel metal complex for the perfluoropolyether polymerization catalyst (3.56g, yield 57%), with formula (III-2) shown Structure.

HPLC purity: 98.8%. Mass Spec: Calculated 464.06; Tested 464.31. Elemental analysis: Calculated values: C: 44.00%; H: 6.52%; N: 3.02%; tested values: C: 44.12%; H: 6.61%; N: 3.11%.

Example 4

Raw material A is the same as Example 1;

Raw material B has the structure shown in formula (II-2), Ni(PEt ₃ ) ₄ ;

The catalyst has the structure shown in formula (III-2):

The described preparation method of the catalyst used for perfluoropolyether polymerization comprises the following steps:

Step 1: Under nitrogen protection system, weigh raw materials Ni(cod) ₂ (117.1 mmol, 32.21 g), PEt ₃ (250.59 mmol, 29.61 g), add them into the reaction system, add 450 mL of THF solution, and under nitrogen protection, 45° C. The reaction was carried out for 6 h, then cooled to room temperature, the solvent THF was drained, extracted with n-pentane, and the extract was placed in a 0°C refrigerator to obtain orange-red rod-like crystals, B (32.98 g, yield 53%).

Step 2: Weigh raw material B (59.23 mmol, 31.47 g), add raw material A (68.11 mmol, 11.51 g), then add 155 mL of THF to the system, under nitrogen protection, react at 30 ° C for 10 h, drain the solvent, and use n-pentane Washing, drying the residue after washing in a vacuum drying oven to obtain a red nickel metal complex for the perfluoropolyether polymerization catalyst (16.77g, yield 61%), with formula (III-2) Structure.

HPLC purity: 99.2%. Mass Spec: Calculated 464.06; Tested 464.31. Elemental analysis: Calculated values: C: 44.00%; H: 6.52%; N: 3.02%; tested values: C: 43.92%; H: 6.41%; N: 2.94%.

Example 5

Raw material A is the same as Example 1;

Raw material B has a structure represented by formula (II-3), Ni(P ⁱ Pr ₃ ) ₄ ;

The catalyst has the structure shown in formula (III-3):

The described preparation method of the catalyst used for perfluoropolyether polymerization comprises the following steps:

Step 1: Under nitrogen protection system, weigh the raw materials Ni(cod) ₂ (27.3mmol, 7.51g), P ⁱ Pr ₃ (triisopropylphosphine) (57.3mmol, 9.18g) into the reaction system, add 100mL THF solution, refluxed at 60°C for 6h under nitrogen protection, then cooled to room temperature, there was precipitation, the solvent THF was drained, extracted with n-pentane, the extract was placed in a 0°C refrigerator to obtain yellow block crystals, which were raw materials B (9.83 g, 63% yield).

Step 2: Weigh raw material B (22.3 mmol, 12.74 g), add raw material A (26.76 mmol, 4.52 g), then add THF 60 mL to the system, under nitrogen protection, react at 40 °C for 8 h, drain the solvent, n-pentane Washing, draining the n-pentane, drying in a vacuum drying oven, finally obtaining the catalyst (3.37g, yield 39%) that the final yellow nickel metal complex is used for the perfluoropolyether polymerization reaction, with the formula ( The structure shown in III-3).

HPLC purity: 99.1%. Mass Spec: Calculated 387.98; Tested 387.49. Elemental analysis: Calculated values: C: 43.34%; H: 5.46%; N: 3.61%; tested values: C: 43.24%; H: 5.22%; N: 3.91%.

Example 6

Raw material A is the same as Example 1;

Raw material B has a structure represented by formula (II-3), Ni(P ⁱ Pr ₃ ) ₄ ;

The catalyst has the structure shown in formula (III-3):

The described preparation method of the catalyst used for perfluoropolyether polymerization comprises the following steps:

Step 1: Under nitrogen protection system, weigh the raw materials Ni(cod) ₂ (79.5mmol, ^21.87g ), Pi Pr ₃ (174.9mmol, 28.02g), then add THF 300mL to the system, under nitrogen protection, 60 ℃ The reaction was carried out for 6 h, and then cooled to room temperature, and a precipitate was precipitated. The solvent THF was drained, extracted with n-pentane, and the extract was placed in a refrigerator at 0 °C to obtain orange block crystals, which was raw material B (30.4 g, yield 67 %).

Step 2: Weigh raw material B (47.78 mmol, 27.30 g), add raw material A (62.11 mmol, 10.50 g), then add THF 150 mL to the system, under nitrogen protection, react at 40 °C for 8 h, drain the solvent, n-pentane After washing, the n-pentane was drained and dried in a vacuum drying oven to obtain an orange-red powdery nickel metal complex for perfluoropolyether polymerization catalyst (7.60g, yield 41%), It has the structure represented by formula (III-3).

HPLC purity: 98.9%. Mass Spec: Calculated 387.98; Tested 387.63. Elemental analysis: Calculated values: C: 43.34%; H: 5.46%; N: 3.61%; tested values: C: 43.19%; H: 5.61%; N: 3.70%.

In the K-type perfluoropolyether polymerization reaction, the catalyst metal nickel complexes and inorganic metal fluorides for the perfluoropolyether polymerization reaction obtained by the reactions in the above-mentioned Examples 1-6 were respectively added. By comparing the polymerization results, It is concluded that the catalytic effect of metal nickel complexes is obviously better than that of inorganic metal fluorides. The specific experimental conditions are: under the protection of high-purity nitrogen, add 47g of catalyst, 476g of acetonitrile and 1700g of hexafluoropropylene oxide into a 5L mechanical stirring kettle. The effects of different catalysts on the polymerization of hexafluoropropylene oxide were investigated under the conditions of a reaction temperature of -40 °C and a reaction time of 12 h. The results are shown in Table 1.

Table 1 Effects of different catalysts on polymerization

catalyst yield Average degree of polymerization DPn(GC) Average degree of polymerization DPn (NMR) CsF 43 4.6 4.7 III-1 83 15.1 15.2 III-2 74 11.7 11.8 III-3 71 10.9 11.0

It can be seen from the above table that in this polymerization reaction, when the metal organic complex of the present invention is used as a catalyst, the yield of the polymerization reaction and the degree of polymerization of perfluoropolyether can be significantly improved; especially when III-1 is used as a catalyst , the yield of the polymer product is the highest, and the average degree of polymerization is the largest. This shows that the solubility of the catalyst in the solvent has a great influence on the polymerization reaction. When the solubility of the catalyst is higher, it is easier to ionize into the solvent to form an active ion-pine pair to react with hexafluoropropylene oxide. In addition, for organometallic complexes, the substituents coordinating with the metal also have a great influence on the catalytic activity of the catalyst; when the steric hindrance of the substituent is smaller, the electron-donating property of the substituent is stronger, making the catalyst more It is easy to react with hexafluoropropylene oxide, thereby improving the yield of the product and the degree of polymerization.

Of course, the above contents are only preferred embodiments of the present invention, and should not be considered as limiting the scope of the embodiments of the present invention. The present invention is not limited to the above examples, and equivalent changes and improvements made by those of ordinary skill in the technical field within the essential scope of the present invention should all belong to the scope of the patent of the present invention.

Claims (8)

1. a catalyzer is used for the purposes of preparing perfluoropolyether, it is characterized in that: catalyzer preparation comprises the following steps: (1) Mix and react Ni(cod) ₂ and PQ ₃ in a solvent to prepare raw material B, where Q=Me, Et or ⁱ Pr; (2) Activating the C-F bond between the raw material B and the raw material A in a solvent to obtain a catalyst for the perfluoropolyether polymerization reaction; in: The structural formula (II) of raw material B is selected from: Ni(PMe ₃ ) ₄ (II-1) Ni(PEt ₃ ) ₄ (II-2) Ni(P ⁱ Pr ₃ ) ₄ (II-3 ) The structural formula (I) of raw material A is:

(I) The structural formula (III) of the catalyst is:

(III) (III): R=PMe ₃ , PEt ₃ or P ⁱ Pr ₃ ; The precipitate in the reaction solution obtained in the step (1) is subjected to suction filtration, and n-pentane is used to extract the precipitated solid, and then the extract is recrystallized to obtain raw material B; The activation reaction process described in the step (2) is as follows: the raw material B and the raw material A obtained in the step (1) are injected into the solvent using a syringe under the condition of protective gas, and the C-F bond activation reaction is carried out, and the obtained reaction The precipitate in the liquid is filtered with suction, and then the precipitated solid is washed with n-pentane, and the washed solid is dried to obtain a catalyst for the perfluoropolyether polymerization reaction. 2 . The use of the catalyst according to claim 1 for preparing perfluoropolyether, wherein the solvent described in step (1) and step (2) is an aprotic solvent. 3 . 3. The use of the catalyst according to claim 1 for preparing perfluoropolyether, wherein the molar ratio of Ni(cod) ₂ and PQ ₃ described in step (1) is 12～15:25～ 32. 4 . The use of the catalyst according to claim 1 for preparing perfluoropolyether, wherein the mixing temperature in step (1) is 20°C to 80°C, and the mixing reaction time is 4 to 10 hours. 5 . 5. The use of the catalyst according to claim 1 for preparing perfluoropolyether, characterized in that: the ratio of the amount of Ni(cod) ₂ and PQ ₃ described in the step (1) to the amount of the solvent 71-90 mmol: 50-100 mL. 6 . The use of the catalyst according to claim 1 for preparing perfluoropolyether, wherein the molar ratio of raw material B and raw material A in step (2) is 8-9:10-12. 7 . 7 . The use of the catalyst according to claim 1 for preparing perfluoropolyether, characterized in that: the ratio of the total amount of the material of the raw material B and the raw material A described in the step (2) to the amount of the solvent is 40～ 60 mmol: 10-60 mL. 8 . The use of the catalyst according to claim 1 for preparing perfluoropolyether, wherein the reaction temperature in step (2) is 25°C to 40°C, and the reaction time is 6h to 12h. 9 .