A cobalt metal complex and its preparation method and application

Abstract

The present application relates to the field of perfluoropolyether catalysts and discloses a cobalt metal complex, a preparation method and an application thereof. The cobalt metal complex is prepared by reacting the raw material 1,2-bis(2,6-difluorobenzylidene)hydrazine with tetrakis(trimethylphosphine)methylcobalt represented by formula (II). The cobalt metal complex is used as a catalyst for the polymerization of K-type perfluoropolyether. Compared with the K-type perfluoropolyether prepared using a fluorine-containing inorganic salt as a catalyst, under the condition of the same catalyst dosage, the yield of the cobalt metal complex used as a catalyst is higher than that of the fluorine-containing inorganic salt, and the yield and polymerization degree of the K-type perfluoropolyether are significantly higher.

Description

Technical Field

[0001] The present invention relates to the field of perfluoropolyether catalysts, in particular to a cobalt metal complex and a preparation method and application thereof. Background Art

[0002] Perfluoropolyether (PFPE) is a high-molecular-weight polymer that is a colorless, odorless, viscous, oily liquid at room temperature. Compared to hydrocarbon compounds, the F atoms in perfluoropolyether molecules replace all H atoms, and all C-H bonds are replaced by higher-energy C-F bonds. The shielding effect of C-F bonds on the main chain C-C and C-O bonds gives perfluoropolyether excellent chemical stability, oxidation resistance, and corrosion resistance. Due to the strong electronegativity of F atoms, there is less intermolecular attraction, resulting in less tension and excellent lubricity and permeability. The stabilized product, perfluoropolyether, can be used as a high-performance lubricant, and its modified products are used in fields such as fluorinated surfactants.

[0003] K-type perfluoropolyether is obtained by anionic polymerization. The monomer of the anionic polymerization process for synthesizing perfluoropolyether is hexafluoropropylene oxide. Hexafluoropropylene oxide is formed by anionic polymerization reaction in a non-protonic polar solvent with fluoride ions as catalyst. Its structural formula is:

[0004]

[0005] Regarding the catalysts used in the polymerization of K-type perfluoropolyethers, many researchers, both domestically and internationally, have conducted a series of screening efforts to identify catalyst types and systems. Earl Philli et al. polymerized a high-molecular-weight perfluoropolyether using an alkali metal fluoride salt as a catalyst and tetraethylene glycol dimethyl ether as a solvent under dry ice cooling to -78°C. Vacuum distillation removed most of the oligomers, yielding a perfluoropolyether with an average degree of polymerization of 33.5. Arbogast et al. also polymerized a high-molecular-weight perfluoropolyether using an alkali metal fluoride salt as a catalyst and poly(ethylene glycol dimethyl ether) as a solvent. Duan Youlu et al. in China used potassium fluoride as a catalyst and diethylene glycol dimethyl ether as a solvent to obtain a perfluoropolyether with a degree of polymerization of 7 at -30°C to 15°C. Heinrich et al. used AgNO₃ as a catalyst, rather than a fluorine-containing catalyst, in the aprotic polar solvent acetonitrile to synthesize oligomers of perfluoropolyether, primarily dimers. Kuhne et al. in Germany used a CuCl / CuCl2 acrylonitrile catalytic system to polymerize hexafluoropropylene oxide in acetonitrile, and the product was also primarily a dimer. Yoshida et al. in Japan used the alkali metal fluoride CsF as a catalyst to polymerize hexafluoropropylene oxide in an aprotic polar solvent at a reaction temperature of -20°C.

[0006] The K-type perfluoropolyether obtained by the above polymerization method has low catalytic activity with potassium fluoride, making it impossible to obtain a perfluoropolyether with a high degree of polymerization. Cesium fluoride has relatively higher catalytic activity than potassium fluoride, but the product is expensive and highly hygroscopic. Therefore, using alkali metal fluoride as a catalyst not only results in a low degree of polymerization and low yield of perfluoropolyether, but also creates difficulties in industrial scale-up. Therefore, there is an urgent need to propose a solution to the above technical problems. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the present invention provides a cobalt metal complex and its preparation method and application. The cobalt metal complex catalyst prepared by this method can effectively prepare K-type perfluoropolyether with high polymerization degree, improve the yield, and effectively reduce the production cost of K-type perfluoropolyether.

[0008] In a first aspect, the present application provides a cobalt metal complex, which adopts the following technical solution:

[0009] A cobalt metal complex, the structural formula of the cobalt metal complex is shown in formula (III):

[0010]

[0011] It is prepared from 1,2-bis(2,6-difluorobenzylidene)hydrazine represented by formula (I) and tetrakis(trimethylphosphine)methylcobalt represented by formula (II), and the reaction process is as follows:

[0012]

[0013] By employing this technical solution, 1,2-bis(2,6-difluorobenzylidene)hydrazine combines with tetrakis(trimethylphosphine)methylcobalt to form a novel cobalt metal complex. When used as a perfluoropolyether catalyst, the fluorine atoms attached to the cobalt metal atoms are more easily detached, causing the fluoride ion concentration in the reaction system to increase as the reaction proceeds. Hexafluoropropylene oxide is more likely to undergo ring-opening polymerization at higher fluoride ion concentrations, thereby increasing the yield and degree of polymerization, alleviating the difficulties in industrial scale-up.

[0014] Preferably, the molar ratio of the 1,2-bis(2,6-difluorobenzylidene)hydrazine to tetrakis(trimethylphosphine)methylcobalt is 1:1 to 1.5.

[0015] By adopting the above technical solution, the reaction between 1,2-bis(2,6-difluorobenzylidene)hydrazine and tetrakis(trimethylphosphine)methylcobalt is relatively complete, and the utilization rate of raw materials is relatively high.

[0016] Preferably, the molar ratio of 1,2-bis(2,6-difluorobenzylidene)hydrazine to tetrakis(trimethylphosphine)methylcobalt is 1:1.01.

[0017] By adopting the above technical solution, the reaction of 1,2-bis(2,6-difluorobenzylidene)hydrazine and tetrakis(trimethylphosphine)methylcobalt is more complete, and the yield of the cobalt metal complex obtained by the reaction is higher.

[0018] Preferably, the steps of the method for preparing tetrakis(trimethylphosphine)methylcobalt are as follows:

[0019] (1) Preparation of tetrakis(trimethylphosphine)cobalt

[0020] Under nitrogen protection, add 3.2-8g of anhydrous cobalt chloride and 2-4g of magnesium to a Schenkfritte, evacuate, activate at 1000-1200°C, add 80-120mL of tetrahydrofuran solvent, keep the temperature at 65-75°C under vacuum, then cool to -90--80°C, add 8.8-19.2g of trimethylphosphine, raise the temperature to 20-30°C, react for 2-4h, evacuate, extract 1-3 times, filter, and dry;

[0021] (2) Preparation of tetrakis(trimethylphosphine)cobalt chloride

[0022] First, evacuate the system. Under nitrogen protection, add 2-5 g of anhydrous cobalt chloride and 100 mL of tetrahydrofuran solvent to the Schenkfritte. The vacuum system temperature is 65-75° C., then cooled to -90--80° C., add 2.8-8 g of trimethylphosphine, and heat to 20-35° C. to obtain a reaction solution. Then, 5.2-16 g of tetrakis(trimethylphosphine)cobalt is mixed with the above reaction solution, stirred for 2-4 hours, filtered, recrystallized, washed, and dried.

[0023] (3) Preparation of tetrakis(trimethylphosphine)methylcobalt

[0024] Mix 1.5-2.5 g of trimethylphosphine, 4.8-9 g of tetrakis(trimethylphosphine)cobalt chloride and 60-80 mL of anhydrous methyl tert-butyl ether, cool to -90--80° C., add 0.0030-0.0065 g of methyllithium with stirring, raise the temperature to 20-35° C., evacuate, extract 1-3 times, filter, maintain the pressure at -0.12--0.08 MPa, filter, and dry.

[0025] By adopting the above technical solution, the tetrakis(trimethylphosphine)methylcobalt complex is prepared with a high yield, which reduces the loss of raw materials, reduces the cost of the cobalt metal complex, indirectly improves the yield, and is more suitable for industrial production.

[0026] In a second aspect, the present application provides a method for preparing a cobalt metal complex, which adopts the following technical solution:

[0027] A method for preparing a cobalt metal complex comprises the following steps:

[0028] Under the protection of nitrogen, 1,2-bis(2,6-difluorobenzylidene)hydrazine of formula (I) and tetrakis(trimethylphosphine)methylcobalt of formula (II) are reacted in a protective solvent. After the reaction is completed, the mixture is concentrated, extracted with methyl tert-butyl ether, and dried in vacuum to obtain a cobalt metal complex.

[0029] By adopting the above technical solution, the synthesized cobalt metal complex requires less raw materials, has a simple preparation process, and has undemanding conditions, and the product is easy to obtain with high yield.

[0030] Preferably, the volume ratio of the amount of the 1,2-bis(2,6-difluorobenzylidene)hydrazine and tetrakis(trimethylphosphine)methylcobalt to the solvent is 1 mmol:10-16 mL.

[0031] By adopting the above technical solution, the preparation reaction rate is kept stable and the yield is effectively improved.

[0032] Preferably, the reaction temperature of the 1,2-bis(2,6-difluorobenzylidene)hydrazine and tetrakis(trimethylphosphine)methylcobalt is 15-40° C. and the reaction time is 12-24 hours.

[0033] By adopting the above technical solution and under the above reaction regulation, the reaction between 1,2-bis(2,6-difluorobenzylidene)hydrazine and tetrakis(trimethylphosphine)methylcobalt is carried out more efficiently and stably, so that the cobalt metal complex finally obtained has a higher yield.

[0034] Preferably, the protective solvent includes one or a combination of n-pentane, n-hexane, cyclohexane, n-heptane, and n-octane.

[0035] By adopting the above technical solution, the above types of solvents and combinations of different solvents are all suitable for the reaction system of the present invention, and bring excellent and stable protection during the reaction process, ensuring that the obtained cobalt metal complex has a stable and high yield.

[0036] In a third aspect, the present application provides a cobalt metal complex, which adopts the following technical solution:

[0037] Application of cobalt metal complexes in the preparation of K-type perfluoropolyether.

[0038] By adopting the above technical solution, the cobalt metal complex catalyst prepared enables the perfluoropolyether to have a higher average polymerization degree.

[0039] In summary, this application has the following beneficial effects:

[0040] The cobalt metal complex provided by the present invention is prepared by selecting a specific ligand to obtain a cobalt organometallic compound, which is used as a catalyst for the polymerization of K-type perfluoropolyether. Compared with the K-type perfluoropolyether prepared using a fluorine-containing inorganic salt as a catalyst, the yield of the cobalt metal complex used as a catalyst is higher than that of the fluorine-containing inorganic salt under the condition of the same catalyst dosage, and the yield and polymerization degree of the K-type perfluoropolyether are significantly higher. DETAILED DESCRIPTION

[0041] The present invention will be further described below with reference to the examples.

[0042] Unless otherwise specified, the raw materials used in the examples of this application are commercially available: 1,2-bis(2,6-difluorobenzylidene)hydrazine, CAS No.: 764663-55-0.

[0043] Preparation examples of raw materials and / or intermediates

[0044] Preparation Example 1

[0045] Tetrakis(trimethylphosphine)methylcobalt, which is prepared by the following steps:

[0046] S1. Under nitrogen protection, 3.2 g of anhydrous cobalt chloride and 2 g of magnesium were added to a Schenkfritte, vacuumed, activated at 1000°C, and then 80 mL of tetrahydrofuran solvent was added. The temperature was kept at 65°C under vacuum, then cooled to -80°C, 8.8 g of trimethylphosphine was added, and the temperature was raised to 20°C for reaction for 2 h. The mixture was vacuumed, extracted once, filtered, and dried to obtain tetrakis(trimethylphosphine)cobalt;

[0047] S2, first evacuate, under nitrogen protection, 2g of anhydrous cobalt chloride and 80mL of tetrahydrofuran solvent are added to Schenkfritte, the temperature is at 65 ℃ under vacuum, then cooled to-90 ℃, after adding 2.8g of trimethylphosphine, warming to 20 ℃, obtain reaction solution, then after 5.2g of tetrakis (trimethylphosphine) cobalt and above-mentioned reaction solution are mixed, stir, temperature remains at 20 ℃, reaction time is 2h, filter, recrystallize, wash, dry, obtain tetrakis (trimethylphosphine) cobalt chloride;

[0048] S3. Mix 1.5 g of trimethylphosphine and 4.8 g of tetrakis(trimethylphosphine)cobalt chloride in 60 mL of anhydrous methyl tert-butyl ether solvent, cool to -90 ° C, add 0.0030 g of methyllithium, stir evenly, heat to 20 ° C for 2 h, vacuum, extract once, filter, maintain the pressure at -0.12 MPa, filter, and dry to obtain tetrakis(trimethylphosphine)cobalt methyl (5.8 g, yield 92%).

[0049] Preparation Example 2

[0050] Tetrakis(trimethylphosphine)methylcobalt, which is prepared by the following steps:

[0051] Under nitrogen protection, 8 g of anhydrous cobalt chloride and g of magnesium were added to a Schenkfritte, vacuumed, activated at 1200°C, and then 120 mL of tetrahydrofuran solvent was added. The temperature was kept at 75°C under vacuum, then cooled to -80°C, and 19.2 g of trimethylphosphine was added. The temperature was raised to 30°C, reacted for 4 h, vacuumed, extracted three times, filtered, and dried to obtain tetrakis(trimethylphosphine)cobalt;

[0052] First, evacuate the system. Under nitrogen protection, add 5 g of anhydrous cobalt chloride and 120 mL of tetrahydrofuran solvent to the Schenkfritte. The vacuum system temperature is 75°C, then cooled to -80°C, 8 g of trimethylphosphine is added, and the temperature is raised to 35°C to obtain a reaction solution. Then, 16 g of tetrakis(trimethylphosphine)cobalt is mixed with the above reaction solution, stirred evenly, and the temperature is maintained at 35°C. The reaction time is 4 hours, filtered, recrystallized, washed, and dried to obtain tetrakis(trimethylphosphine)cobalt chloride;

[0053] 2.5 g of trimethylphosphine, 9 g of tetrakis(trimethylphosphine)cobalt chloride and 80 mL of anhydrous methyl tert-butyl ether were mixed, cooled to -80°C, 0.0065 g of methyllithium was added, stirred evenly, heated to 35°C, reacted for 4 h, vacuumed, extracted 3 times, filtered, filtered while maintaining the pressure at -0.08 MPa, and dried to obtain tetrakis(trimethylphosphine)cobalt methyl (10.82 g, yield 94%).

[0054] Preparation Example 3

[0055] Tetrakis(trimethylphosphine)methylcobalt, which is prepared by the following steps:

[0056] Under nitrogen protection, 6.2 g of anhydrous cobalt chloride and 3.4 g of magnesium were added to a Schenkfritte, and the mixture was evacuated. After activation at 1100°C, 100 mL of tetrahydrofuran solvent was added, the temperature was kept at 70°C under vacuum, and then cooled to -85°C. After adding 12.4 g of trimethylphosphine, the mixture was heated to 25°C and reacted for 3 h. The mixture was evacuated, extracted twice, filtered, and dried to obtain tetrakis(trimethylphosphine)cobalt.

[0057] First, evacuate the system. Under nitrogen protection, add 4 g of anhydrous cobalt chloride and 100 mL of tetrahydrofuran solvent to the Schenkfritte. The vacuum system temperature is 70°C, then cooled to -85°C, 4.4 g of trimethylphosphine is added, and the temperature is raised to 30°C to obtain a reaction solution. Then, 8.4 g of tetrakis(trimethylphosphine)cobalt is mixed with the above reaction solution, stirred evenly, and the temperature is maintained at 30°C. The reaction time is 3 h, filtered, recrystallized, washed, and dried to obtain tetrakis(trimethylphosphine)cobalt chloride;

[0058] 2.2 g of trimethylphosphine, 5.6 g of tetrakis(trimethylphosphine)cobalt chloride and 70 mL of anhydrous methyl tert-butyl ether were mixed, cooled to -85°C, 0.0048 g of methyllithium was added, stirred evenly, heated to 30°C, reacted for 3 h, vacuumed, extracted twice, filtered, filtered while maintaining the pressure at -0.1 MPa, and dried to obtain tetrakis(trimethylphosphine)cobalt methyl (7.42 g, yield 95%).

[0059] Example

[0060] Example 1

[0061] A cobalt metal complex, the structural formula of the cobalt metal complex is shown in formula (III):

[0062]

[0063] The reaction process of 1,2-bis(2,6-difluorobenzylidene)hydrazine represented by formula (I) and tetrakis(trimethylphosphine)methylcobalt represented by formula (II) is as follows:

[0064]

[0065] 1,2-Bis(2,6-difluorobenzylidene)hydrazine (19.1 mmol, 5.4 g) was weighed, and tetrakis(trimethylphosphine)methylcobalt (19.1 mmol, 7.2 g) was added. 380 mL of n-pentane was then added to the reaction mixture at 0°C. Under nitrogen, the reaction temperature was maintained at 15°C for 12 h. The product was concentrated, extracted with methyl tert-butyl ether, and dried under vacuum to obtain a red powdery solid having the structure represented by Formula (III). HPLC purity: 99.1%. Mass spectrum: Calculated: 506.35; Assay: 506.72. Elemental analysis: Calculated: C 49.82; H 5.77; N 5.53. Assay: C 49.79; H 5.83; N 5.61. IR(Nujol): 1623.1, 1607.7(C=N); 1592.4, 1555.4(C=C); 950.8(PMe3)cm -1 (Tetrakis(trimethylphosphine)methylcobalt is obtained from Preparation Example 3)

[0066] Example 2

[0067] A cobalt metal complex, the structural formula of the cobalt metal complex is shown in formula (III):

[0068]

[0069] The reaction process of 1,2-bis(2,6-difluorobenzylidene)hydrazine represented by formula (I) and tetrakis(trimethylphosphine)methylcobalt represented by formula (II) is as follows:

[0070]

[0071] 1,2-Bis(2,6-difluorobenzylidene)hydrazine (24.6 mmol, 6.9 g) was weighed, and tetrakis(trimethylphosphine)methylcobalt (37 mmol, 14 g) was added. 620 mL of n-pentane was then added to the reaction mixture at 0°C. Under nitrogen, the reaction temperature was maintained at 15°C for 12 hours. The product was concentrated, extracted with methyl tert-butyl ether, and dried under vacuum to obtain a red powdery solid with the structure represented by Formula (III). HPLC purity: 99.2%. Mass spectrum: Calculated: 506.35; Assay: 505.93. Elemental analysis: Calculated: C 49.82; H 5.77; N 5.53. Assay: C 49.21; H 5.24; N 5.17. IR(Nujol): 1621.8, 1606.1(C=N); 1590.5, 1553.4(C=C); 948.1(PMe3)cm -1 (Tetrakis(trimethylphosphine)methylcobalt is obtained from Preparation Example 3)

[0072] Example 3

[0073] A cobalt metal complex, the structural formula of the cobalt metal complex is shown in formula (III):

[0074]

[0075] The reaction process of 1,2-bis(2,6-difluorobenzylidene)hydrazine represented by formula (I) and tetrakis(trimethylphosphine)methylcobalt represented by formula (II) is as follows:

[0076]

[0077] 1,2-Bis(2,6-difluorobenzylidene)hydrazine (51.7 mmol, 14.5 g) was weighed and tetrakis(trimethylphosphine)methylcobalt (62.0 mmol, 23.5 g) was added. 1140 mL of n-pentane was then added to the reaction mixture at 0°C. Under nitrogen, the reaction temperature was maintained at 15°C for 12 hours. The product was concentrated, extracted with methyl tert-butyl ether, and dried under vacuum to obtain a red powdery solid having the structure represented by Formula (III). HPLC purity: 98.6%. Mass spectrum: Calculated: 506.35; Assay: 506.11. Elemental analysis: Calculated: C 49.82; H 5.77; N 5.53. Assay: C 49.47; H 5.54; N 5.21. IR(Nujol): 1622.0, 1606.5(C=N); 1591.1, 1553.9(C=C); 948.8(PMe3)cm -1 (Tetrakis(trimethylphosphine)methylcobalt is obtained from Preparation Example 3)

[0078] Example 4

[0079] A cobalt metal complex, the structural formula of the cobalt metal complex is shown in formula (III):

[0080]

[0081] The reaction process of 1,2-bis(2,6-difluorobenzylidene)hydrazine represented by formula (I) and tetrakis(trimethylphosphine)methylcobalt represented by formula (II) is as follows:

[0082]

[0083] 1,2-Bis(2,6-difluorobenzylidene)hydrazine (97.4 mmol, 27.3 g) was weighed and tetrakis(trimethylphosphine)methylcobalt (98.4 mmol, 37.2 g) was added. 1960 mL of n-pentane was then added to the system at 0°C. Under nitrogen, the reaction temperature was set at 15°C for 12 hours. The product was concentrated, extracted with methyl tert-butyl ether, and dried under vacuum to obtain a red powdery solid with the structure represented by Formula (III). HPLC purity: 99.4%. Mass spectrum: Calculated: 506.35; Assay: 506.64. Elemental analysis: Calculated: C 49.82; H 5.77; N 5.53. Assay: C 49.84; H 5.87; N 5.69. IR(Nujol): 1622.7, 1607.3(C=N); 1591.9, 1554.8(C=C); 950.4(PMe3)cm -1 (Tetrakis(trimethylphosphine)methylcobalt is obtained from Preparation Example 3)

[0084] Example 5

[0085] A cobalt metal complex, the structural formula of the cobalt metal complex is shown in formula (III):

[0086]

[0087] The reaction process of 1,2-bis(2,6-difluorobenzylidene)hydrazine represented by formula (I) and tetrakis(trimethylphosphine)methylcobalt represented by formula (II) is as follows:

[0088]

[0089] 1,2-Bis(2,6-difluorobenzylidene)hydrazine (97.4 mmol, 27.3 g) was weighed, and tetrakis(trimethylphosphine)methylcobalt (87.8 mmol, 33.4 g) was added. 1960 mL of n-pentane was then added to the system at 0°C. Under nitrogen, the reaction temperature was set at 15°C for 12 hours. The product was concentrated, extracted with methyl tert-butyl ether, and dried under vacuum to obtain a red powdery solid with the structure represented by Formula (III). HPLC purity: 97.4%. Mass spectrum: Calculated: C 49.82; H 5.77; N 5.53. Assay: C 49.18; H 5.02; N 4.98. IR (Nujol): 1622.4, 1602.2 (C=N); 1592.4, 1526.6 (C=C); 930.6 (PMe3)cm -1 (Tetrakis(trimethylphosphine)methylcobalt is obtained from Preparation Example 3)

[0090] Example 6

[0091] A cobalt metal complex, the structural formula of the cobalt metal complex is shown in formula (III):

[0092]

[0093] The reaction process of 1,2-bis(2,6-difluorobenzylidene)hydrazine represented by formula (I) and tetrakis(trimethylphosphine)methylcobalt represented by formula (II) is as follows:

[0094]

[0095] 1,2-Bis(2,6-difluorobenzylidene)hydrazine (97.4 mmol, 27.3 g) was weighed, and tetrakis(trimethylphosphine)methylcobalt (155.8 mmol, 43.6 g) was added. 1960 mL of n-pentane was then added to the system at 0°C. Under nitrogen, the reaction temperature was set at 15°C for 12 hours. The product was concentrated, extracted with methyl tert-butyl ether, and dried under vacuum to obtain a red powdery solid with the structure represented by Formula (III). HPLC purity: 96.4%. Mass spectrum: Calculated: C 49.82; H 5.77; N 5.53. Assay: C 50.12; H 5.82; N 5.78. IR (Nujol): 1590.4, 1542.2 (C=N); 1592.8, 1624.6 (C=C); 980.6 (PMe3)cm -1 (Tetrakis(trimethylphosphine)methylcobalt is obtained from Preparation Example 3)

[0096] Example 7

[0097] A cobalt metal complex, which is different from Example 4 in that tetrakis(trimethylphosphine)methylcobalt is obtained in Preparation Example 1.

[0098] Example 8

[0099] A cobalt metal complex, which is different from Example 4 in that tetrakis(trimethylphosphine)methylcobalt is obtained in Preparation Example 2.

[0100] Example 9

[0101] A cobalt metal complex, which differs from Example 4 in that the volume ratio of the total amount of 1,2-bis(2,6-difluorobenzylidene)hydrazine and tetrakis(trimethylphosphine)methylcobalt to n-pentane is 1 mmol:16 mL, and the total amount of 1,2-bis(2,6-difluorobenzylidene)hydrazine and tetrakis(trimethylphosphine)methylcobalt remains unchanged.

[0102] Example 10

[0103] A cobalt metal complex, which is different from Example 4 in that the volume ratio of the total amount of 1,2-bis(2,6-difluorobenzylidene)hydrazine and tetrakis(trimethylphosphine)methylcobalt to n-pentane is 1 mmol:14 mL, and the total amount of 1,2-bis(2,6-difluorobenzylidene)hydrazine and tetrakis(trimethylphosphine)methylcobalt is 1 mmol:14 mL.

[0104] Example 11

[0105] A cobalt metal complex, which is different from Example 4 in that the reaction temperature of 1,2-bis(2,6-difluorobenzylidene)hydrazine and tetrakis(trimethylphosphine)methylcobalt is 40° C. and the reaction time is 24 hours.

[0106] Example 12

[0107] A cobalt metal complex, which is different from Example 4 in that the reaction temperature of 1,2-bis(2,6-difluorobenzylidene)hydrazine and tetrakis(trimethylphosphine)methylcobalt is 25° C. and the reaction time is 18 hours.

[0108] Application Examples

[0109] Application Example 1

[0110] 8g of cobalt metal complex catalyst was added to 100mL of tetraethylene glycol dimethyl ether at 20°C and stirred for 30min. The above solution was added to a 1L reactor with mechanical stirring under nitrogen protection. Subsequently, 600g of hexafluoropropylene oxide was added to the reactor at one time. The reaction temperature was controlled at -30°C and the reaction time was 6h. After the reaction was completed, the temperature was raised to 20°C, and the feed valve was opened to obtain the product. The product was obtained by gas phase and 19 The average polymerization degrees of the products obtained by F-NMR analysis were 9.0 and 9.5, respectively. (Preparation of Example 4)

[0111] Application Example 2

[0112] 18.3 g of cobalt metal complex catalyst (added amount is 1% mol of hexafluoropropylene oxide) was added to 100 mL of tetraethylene glycol dimethyl ether at 20 ° C and stirred for 30 min. The above solution was added to a 1 L reactor with mechanical stirring under nitrogen protection. Subsequently, 600 g of hexafluoropropylene oxide was added to the reactor at one time. The reaction temperature was controlled at -30 ° C and the reaction time was 6 h. After the reaction was completed, the temperature was raised to 20 ° C, and the feed valve was opened to obtain the product. The product was obtained by gas phase and 19 The average polymerization degrees of the products obtained by F-NMR analysis were 15.1 and 15.6, respectively. (Preparation of Example 4)

[0113] Application comparison

[0114] Comparative Application Example 1

[0115] 8g of cesium fluoride catalyst was added to 100mL of tetraethylene glycol dimethyl ether at 20°C and stirred for 30min. The above solution was added to a 1L reactor with mechanical stirring under nitrogen protection. Subsequently, 600g of hexafluoropropylene oxide was added to the reactor at one time. The reaction temperature was controlled at -30°C and the reaction time was 6h. After the reaction was completed, the temperature was raised to 20°C and the feed valve was opened to obtain the product. The product was obtained by gas phase and 19 F-NMR analysis showed that the average polymerization degrees of the products were 5.1 and 5.4, respectively.

[0116] Application Comparative Example 2

[0117] 18.3 g of cesium fluoride catalyst (added in an amount of 1% mol of hexafluoropropylene oxide) was added to 100 mL of tetraethylene glycol dimethyl ether at 20 ° C and stirred for 30 min. The above solution was added to a 1 L reactor with mechanical stirring under nitrogen protection. Subsequently, 600 g of hexafluoropropylene oxide was added to the reactor at one time. The reaction temperature was controlled at -30 ° C and the reaction time was 6 h. After the reaction was completed, the temperature was raised to 20 ° C, and the feed valve was opened to obtain the product. The product was obtained by gas phase and 19 F-NMR analysis showed that the average polymerization degrees of the products were 4.4 and 4.7, respectively.

[0118] Performance testing

[0119] (1) The yield of the cobalt metal complex prepared in Examples 1-12 was calculated using the following formula: Yield (%) = total mass of output / total mass of raw materials × 100%. The corresponding results are recorded in Table 1.

[0120] (2) The cobalt metal complex and inorganic fluoride prepared in this application were used as catalysts in the polymerization reaction of K-type perfluoropolyether, and the polymerization reaction was carried out under the same experimental conditions. The gas phase and nuclear magnetic resonance fluorine spectroscopy were used to analyze the reaction. 19 The average degree of polymerization of the product was obtained by F-NMR, and the results were recorded in Table 2.

[0121] Table 1 Yield of prepared cobalt metal complexes

[0122]

[0123]

[0124] Table 2 Effects of different catalysts on polymerization reaction

[0125]

[0126] From Examples 1 to 4 and Table 1, it can be seen that when the cobalt organometallic complex catalyst is used in the reaction of K-type perfluoropolyether, hexafluoropropylene oxide is more likely to undergo ring-opening polymerization, resulting in increased yield and degree of polymerization.

[0127] In conjunction with Examples 1-6 and Table 1, it can be seen that when the molar ratio of 1,2-bis(2,6-difluorobenzylidene)hydrazine to tetrakis(trimethylphosphine)methylcobalt is within the range of 1:1 to 1.5, the yield obtained in the experiment is relatively high. When the molar ratio exceeds the above range, whether it is lower or higher than the molar ratio, the yield will be low, which has a certain impact on cost reduction. It can be seen that when the molar ratio of 1,2-bis(2,6-difluorobenzylidene)hydrazine to tetrakis(trimethylphosphine)methylcobalt is within the range of 1:1 to 1.5, the yield of the cobalt metal complex is high.

[0128] In combination with Examples 8-12 and Table 1, it can be seen from the experimental results that the experiment should be carried out under the synergistic conditions of a molar ratio of 1,2-bis(2,6-difluorobenzylidene)hydrazine to tetrakis(trimethylphosphine)methylcobalt of 1:1.01, a volume ratio of the amount of 1,2-bis(2,6-difluorobenzylidene)hydrazine and tetrakis(trimethylphosphine)methylcobalt to n-pentane of 1 mmol:14 mL, a reaction temperature of 25 ° C, and a reaction time of 18 h. The yield of the cobalt metal complex under these conditions is higher than that under other ranges.

[0129] Combining Application Examples 1-2, Application Comparative Examples 1-2 and Table 2, it can be seen that after the reaction, when the cobalt metal complex catalyst and the fluorinated alkali metal catalyst have the same mass, the product yield using the cobalt metal complex catalyst is higher than the product yield using the fluorinated alkali metal catalyst.

[0130] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. Use of a cobalt metal complex in catalyzing the ring-opening polymerization of hexafluoropropylene oxide to prepare K-type perfluoropolyether, characterized in that: The structural formula of the cobalt metal complex is as follows:

Images